How to Calculate Customer Acquisition Cost for a Service Business

A service business can generate lots of leads and still have poor marketing economics.

Imagine two companies.

Company A

Spends:

£5,000 on marketing

and wins:

50 new customers.

Customer acquisition cost:

£100

Company B

Spends:

£5,000

and wins:

20 new customers.

Customer acquisition cost:

£250

Company A appears more efficient.

But that still does not tell the full story.

What if Company A’s customers only buy:

£150 jobs

while Company B’s customers generate:

£2,000 of gross profit over time?

That is why customer acquisition cost for a service business should never be viewed in isolation.

A stronger marketing model connects:

Marketing Spend

↓

Leads

↓

Booked Jobs

↓

New Customers

↓

Customer Acquisition Cost

↓

Gross Profit

↓

Customer Lifetime Value

The goal is not simply:

get cheaper leads.

The goal is:

acquire profitable customers at a sustainable cost.

What Is Customer Acquisition Cost?

Customer acquisition cost, usually shortened to:

CAC

measures how much a business spends to acquire a new customer.

A simple formula is:

Sales + Marketing Costs ÷ New Customers Acquired = CAC

For example:

Marketing and sales costs:

£8,000

New customers:

80

CAC:

£100

That means the business spent an average of:

£100

to acquire each new customer.

Why CAC Matters

Marketing should not only generate:

• clicks;
• calls;
• leads.

It should generate:

profitable customers.

CAC helps answer:

How much are we paying to win each new customer?

Once you know that, you can compare it with:

• first job gross profit;
• repeat revenue;
• customer lifetime value.

That is much more useful than looking at:

cost per lead alone.

CAC vs Cost Per Lead

These are different.

Cost Per Lead

Formula:

Marketing Spend ÷ Leads

Example:

£5,000 spend.

250 leads.

Cost per lead:

£20

Customer Acquisition Cost

Suppose only:

50 of those leads become new customers.

CAC:

£5,000 ÷ 50 = £100

The £20 lead looked cheap.

But the real customer acquisition cost was:

£100.

Why Cost Per Lead Can Mislead You

Consider two campaigns.

Campaign A

Cost per lead:

£20

Lead-to-customer conversion:

10%

Campaign B

Cost per lead:

£40

Lead-to-customer conversion:

40%

For 100 leads:

A

Marketing spend:

£2,000

Customers:

10

CAC:

£200

B

Marketing spend:

£4,000

Customers:

40

CAC:

£100

Campaign B has:

twice the lead cost

but:

half the acquisition cost.

Cheap leads are not always better leads.

Step 1: Decide What Costs to Include

For a simple marketing CAC, you might include:

• advertising;
• SEO;
• lead generation platforms;
• marketing agency fees;
• sales software.

For a fuller CAC, you may also include:

• sales staff wages;
• sales commissions;
• call tracking;
• marketing technology;
• creative production.

The important thing is to define the metric consistently.

Simple CAC vs Fully Loaded CAC

Simple CAC

Marketing spend only.

Fully Loaded CAC

Marketing + sales costs.

Both can be useful.

Just label them clearly.

Example

Marketing Costs

Google Ads:

£4,000

SEO:

£1,500

Lead platform:

£500

Total:

£6,000

Sales Costs

Sales wages allocated:

£2,000

CRM / phone:

£500

Total:

£2,500

Fully loaded acquisition spend:

£8,500

New customers:

85

Fully loaded CAC:

£100

Step 2: Count New Customers Correctly

Do not divide acquisition spend by:

all customers.

Use:

new customers acquired during the relevant period.

If you served:

150 customers

but:

70 were existing customers,

new customers:

80

Use:

80

for CAC.

Existing Customers Should Usually Be Separated

Repeat customers often require less acquisition spend.

Mixing:

• new;
• repeat

can make marketing look more efficient than it really is.

Track both.

Step 3: Match the Time Period

Use costs and customers from the same period where practical.

Example:

October acquisition spend:

£10K

New customers:

100

October CAC:

£100

But be careful with:

• SEO;
• long sales cycles.

Some marketing spend produces customers later.

For those channels, longer reporting periods may be more useful.

Step 4: Calculate Overall CAC

Formula:

Total Acquisition Spend ÷ New Customers

Example:

Marketing + sales:

£12,000

New customers:

100

CAC:

£120

Now you have a company-level benchmark.

Step 5: Calculate CAC by Channel

This is where the metric becomes more useful.

Example:

Google Ads

Spend:

£5,000

New customers:

40

CAC:

£125

SEO

Allocated cost:

£2,000

New customers:

35

CAC:

£57.14

Local Service Platform

Spend:

£2,500

New customers:

15

CAC:

£166.67

Referrals

Cost:

£500

New customers:

10

CAC:

£50

Now you know which channels acquire customers most efficiently.

But Do Not Choose Channels Using CAC Alone

Suppose:

Referrals

CAC:

£50

Average first-job gross profit:

£150

Google Ads

CAC:

£125

Average first-job gross profit:

£600

Google Ads costs more.

But may generate more economic value.

You need:

CAC + customer value.

Step 6: Compare CAC With First-Job Gross Profit

Suppose:

CAC:

£100

Average first job:

£500 revenue.

Gross margin:

40%.

Gross profit:

£200

First-job gross profit after acquisition cost:

£100

That is a useful number.

First-Job Acquisition Payback

Formula:

First-Job Gross Profit − CAC

Example:

Gross profit:

£200

CAC:

£100

Remaining:

£100

The customer has already recovered acquisition cost on the first job.

That can be attractive.

Negative First-Job Payback Can Still Work

Suppose:

CAC:

£150

First-job gross profit:

£100

Loss after CAC:

−£50

But customer later generates:

£1,000 gross profit

through repeat work.

Acquiring that customer may still be excellent.

This is why:

Customer Lifetime Value

matters.

Step 7: Compare CAC With Customer Lifetime Value

A simplified customer lifetime value model might consider:

Average Customer Gross Profit × Expected Number of Purchases

Example:

Average gross profit per purchase:

£250

Average purchases:

4

Estimated lifetime gross profit:

£1,000

CAC:

£100

LTV:CAC:

10:1

This can indicate strong economics.

But only if the lifetime value estimate is realistic.

Do Not Use Revenue-Based LTV Without Context

Suppose customer lifetime revenue:

£2,000

Sounds strong.

But if gross margin:

20%,

gross profit:

£400

That is the more relevant value when comparing against CAC.

Use:

gross profit-based lifetime value

where possible.

Step 8: Calculate LTV:CAC Ratio

Formula:

Customer Lifetime Value ÷ CAC

Example:

Lifetime gross profit:

£900

CAC:

£150

Ratio:

6:1

This means the estimated gross profit value of the customer is six times acquisition cost.

Do not treat one ratio as universally ideal.

Different service businesses have different:

• cash flow;
• repeat purchase behavior;
• margins.

Step 9: Calculate CAC Payback Period

CAC payback asks:

How long until gross profit generated by the customer recovers acquisition cost?

Example:

CAC:

£200

Average monthly gross profit from recurring service:

£50

Payback:

4 months

This is particularly useful for:

• cleaning;
• maintenance plans;
• recurring service companies.

Shorter Payback Usually Reduces Risk

If acquisition cost is recovered quickly:

the business can reinvest marketing cash sooner.

Long payback periods require:

• more working capital;
• stronger retention.

Step 10: Track CAC by Service

Different services may have different acquisition economics.

Example:

Emergency Plumbing

CAC:

£90

Average job gross profit:

£280

Boiler Installation

CAC:

£250

Average job gross profit:

£1,200

Annual Maintenance

CAC:

£110

First-year gross profit:

£300

All three may be attractive for different reasons.

Step 11: Track CAC by Customer Type

Example:

Residential

CAC:

£95

Commercial

CAC:

£350

Commercial CAC is much higher.

But commercial customers may have:

• larger contracts;
• repeat work.

Higher acquisition cost is not automatically bad.

Step 12: Track CAC by Geography

You may discover:

Zone A

CAC:

£80

Zone B

CAC:

£140

Zone C

CAC:

£260

Why?

Possible reasons:

• competition;
• distance;
• weak conversion.

This can help improve local marketing.

Step 13: Track CAC by Lead Source

Examples:

• Google Ads;
• organic search;
• referrals;
• Facebook;
• local directories;
• email;
• partnerships.

Do not combine everything into one number if channel decisions matter.

Step 14: Include Lead Conversion Rate

Formula:

New Customers ÷ Leads × 100

Example:

Leads:

200

Customers:

50

Conversion:

25%

If CAC is high:

your marketing may not be the problem.

Maybe:

conversion is weak.

Example

Ad spend:

£5K

Leads:

100

Cost per lead:

£50

Customers:

20

CAC:

£250

Improve conversion from:

20%

to:

30%

Customers become:

30

CAC becomes:

£166.67

Same ad spend.

Same leads.

Much better acquisition cost.

Step 15: Improve Speed to Lead

A customer calling for:

• plumber;
• electrician;
• HVAC repair

may contact multiple companies.

If you respond slowly:

conversion can fall.

Better lead handling can improve CAC without reducing ad spend.

Step 16: Improve Call Answer Rate

Marketing can generate expensive leads.

If nobody answers:

that spend is wasted.

Track:

Calls Answered ÷ Inbound Calls

Suppose:

20% of calls are missed.

Improving phone coverage may reduce acquisition cost significantly.

Step 17: Track Missed-Call Recovery

If a lead calls and nobody answers:

use:

• callback workflow;
• SMS.

Recovering missed leads can improve marketing economics.

Step 18: Improve Quote Follow-Up

Marketing cost has already been spent when the quote is issued.

If quotes are not followed up:

CAC rises.

Example:

100 leads.

40 estimates.

10 customers.

Improve estimate conversion to:

15 customers.

Same marketing spend.

Lower CAC.

Step 19: Improve Lead Qualification

Not every lead is useful.

Bad leads may include:

• outside service area;
• wrong service;
• unrealistic budget.

Improve:

• website messaging;
• campaign targeting.

Better lead quality can improve CAC.

Step 20: Do Not Optimize for Cheap Leads

A cheap lead can still be expensive if:

• poor conversion;
• low job value;
• high cancellation.

Track:

lead → customer → gross profit

not only:

cost per lead.

Channel Example

Channel A

CPL:

£25

Customer conversion:

10%

CAC:

£250

Average gross profit/customer:

£300

Channel B

CPL:

£60

Conversion:

40%

CAC:

£150

Average gross profit/customer:

£700

Channel B looks much stronger despite the expensive leads.

Step 21: Include Marketing Agency Fees

If Google Ads spend is:

£5K

but agency fee:

£1K

total acquisition cost should often include:

£6K

for channel evaluation.

Otherwise CAC looks artificially low.

Step 22: Include Promotional Discounts Carefully

Suppose new customers receive:

£50 discount.

That is part of the economic cost of acquisition.

Whether you classify it inside CAC or gross profit:

be consistent.

Do not ignore it.

Step 23: Track CAC Trend

Example:

January:

£95

February:

£105

March:

£130

April:

£160

CAC is rising.

Why?

Possible causes:

• ads more expensive;
• conversion falling;
• lead quality weaker.

Trend matters more than one month.

Step 24: Track CAC Against Gross Margin

If gross margin declines:

the same CAC becomes more expensive relative to customer value.

Example:

CAC:

£150

At 50% Margin

£1,000 job gross profit:

£500

At 25% Margin

Gross profit:

£250

Acquisition cost now consumes:

60% of gross profit.

Marketing and margin must be reviewed together.

Step 25: Track CAC Against Capacity

Suppose CAC is excellent.

But technicians are fully booked.

Spending more on marketing may simply create:

• longer wait times;
• lost leads.

Marketing spend should match:

available field capacity.

Example

Current utilization:

90%

Appointment wait:

12 days

CAC:

£80

Increasing ad spend may not be the next best decision.

Maybe:

• hire;
• expand capacity

first.

Step 26: Track CAC Against No-Shows

Suppose paid leads book appointments but often no-show.

Marketing acquired:

a booking

not:

a paying customer.

Use:

new paying customers

where practical.

That gives a more realistic acquisition cost.

Step 27: Track CAC Against Cancellations

Lead source A may generate:

cheap bookings.

But:

30% cancel.

Lead source B:

higher CPL.

But:

5% cancel.

Evaluate final customer economics.

Step 28: Track New vs Repeat Revenue

Marketing should create new customers.

But retention turns acquisition into long-term value.

Track:

New Customer Revenue

and:

Repeat Customer Revenue

separately.

If repeat revenue is growing:

CAC may support long-term profitability.

Step 29: Calculate Blended CAC

Formula:

Total Sales & Marketing Spend ÷ Total New Customers

Example:

Spend:

£20K

New customers:

150

Blended CAC:

£133.33

This is useful for company-level performance.

Step 30: Calculate Paid CAC

Use paid channels only.

Example:

Paid advertising:

£12K

New customers from paid marketing:

80

Paid CAC:

£150

This helps isolate paid acquisition efficiency.

Step 31: Calculate Organic CAC Carefully

Organic is not:

free.

SEO may require:

• content;
• agency;
• website work.

If those costs are meaningful:

allocate them.

Step 32: Referrals Also Have Cost

Referral customers may have costs through:

• referral incentives;
• networking;
• partnerships.

Track them where practical.

Step 33: Separate Brand Marketing From Direct Acquisition

Some spending supports:

• awareness

rather than measurable short-term leads.

Do not force every pound into perfect direct attribution.

But understand:

what can be measured

and:

what cannot.

Attribution Is Imperfect

Customer journey may look like:

Google Search

↓

Website

↓

Facebook Retargeting

↓

Referral from Friend

↓

Phone Call

Which channel acquired the customer?

There may not be one perfect answer.

Use attribution models consistently.

Step 34: Ask Customers How They Found You

Even with analytics:

ask.

Example booking field:

How did you hear about us?

Options:

• Google
• Referral
• Facebook
• Repeat Customer
• Other

This provides useful supporting data.

Step 35: Connect CAC to the CRM

For every new customer, ideally track:

Lead Source

↓

Booked Job

↓

Revenue

↓

Gross Profit

This makes channel profitability much easier to analyze.

Marketing Funnel Dashboard

A useful funnel might show:

Marketing Spend: £10K

↓

500 Leads

CPL:

£20

↓

250 Bookings

Cost per Booking:

£40

↓

150 New Customers

CAC:

£66.67

↓

£90K Revenue

↓

£40K Gross Profit

Now you can evaluate the full funnel.

Add Gross Profit Return on Marketing

A useful metric:

Gross Profit Generated ÷ Acquisition Spend

Example:

Gross profit:

£40K

Marketing spend:

£10K

Gross profit return:

4x

This can be more useful than revenue ROAS for service businesses.

Revenue ROAS Can Mislead

Example:

Ad spend:

£10K

Revenue:

£50K

ROAS:

5x

Sounds great.

But if margin:

20%

gross profit:

£10K

Marketing spend:

£10K

You have little contribution remaining.

This is why gross profit matters.

Compare Channels Using Gross Profit

Example:

Channel	CAC	Avg. Customer GP	GP After CAC
Google Ads	£150	£600	£450
SEO	£80	£400	£320
Referral	£50	£300	£250
Lead Platform	£220	£350	£130

Now marketing decisions become clearer.

CAC and Customer Lifetime Value

Suppose:

Google Ads CAC:

£150

Lifetime gross profit:

£1,200

Very attractive.

Lead platform CAC:

£220

Lifetime gross profit:

£350

Much weaker.

Customer quality matters.

CAC and Recurring Services

Recurring businesses can often tolerate higher CAC.

Example:

Monthly gross profit/customer:

£60

Average retention:

24 months

Simplified lifetime gross profit:

£1,440

CAC:

£300

May still be financially attractive.

But cash payback takes time.

CAC and Emergency Services

Emergency services may recover CAC immediately.

Example:

CAC:

£100

First-job gross profit:

£400

Payback:

first job.

This can support faster marketing reinvestment.

CAC and Large Installations

Installations may have:

• higher CAC;
• bigger tickets.

Example:

CAC:

£300

Installation revenue:

£5,000

Gross profit:

£1,500

CAC as percentage of gross profit:

20%

Potentially attractive.

Calculate CAC as Percentage of Gross Profit

Formula:

CAC ÷ Customer Gross Profit × 100

Example:

CAC:

£150

Customer gross profit:

£600

CAC consumes:

25%

of first-job gross profit.

This is easy to understand.

Set CAC Targets Based on Economics

Do not choose:

“CAC must be under £100”

randomly.

Instead ask:

• What is customer gross profit?
• How often do they repeat?
• How quickly is CAC recovered?

Then set a maximum.

Example

Average first-year gross profit/customer:

£800

Business is comfortable spending up to:

20%

on acquisition.

Target CAC:

£160

Now the target has a financial basis.

CAC Can Rise and Still Be Healthy

Suppose CAC rises:

£100 → £130.

Bad?

Maybe not.

If customer gross profit rises:

£400 → £700,

economics improved.

Always compare cost with value.

CAC Can Fall and Still Be Bad

CAC falls:

£150 → £80.

Looks excellent.

But average customer gross profit falls:

£500 → £100.

Marketing may now be acquiring low-value customers.

Cheaper is not automatically better.

Create CAC Alert Levels

Example:

Target:

£120

Green

≤ £120

Yellow

£121–£160

Red

£160

Then combine with:

customer gross profit.

These are illustrative only.

CAC Dashboard

Track:

Marketing Spend

Leads

Cost per Lead

Bookings

New Customers

CAC

Average Customer Gross Profit

LTV

LTV:CAC

Payback Period

This gives a complete acquisition picture.

Example Dashboard

Marketing spend:

£12K

Leads:

400

CPL:

£30

New customers:

80

CAC:

£150

Average first-job gross profit:

£450

Lifetime gross profit:

£1,100

LTV:CAC:

7.3x

Payback:

First Job

Now management can make a better decision.

CAC and Budgeting

If monthly marketing budget is:

£15K

Target CAC:

£150

Expected new customers:

100

If average revenue/customer:

£800

expected first-job revenue:

£80K

This can feed into:

• monthly budget;
• technician capacity plan.

CAC and Technician Capacity

100 new customers may require:

150 technician hours.

Do you have that capacity?

If not:

your marketing plan and operations plan are misaligned.

CAC and Cash Flow

Suppose marketing spend:

£20K today

but customers pay over:

60 days.

The acquisition strategy may be profitable but cash-intensive.

Check:

13-week forecast.

Marketing growth must be fundable.

CAC and Cash Reserve

Aggressive customer acquisition may temporarily use cash.

Do not drain:

• payroll reserve;
• emergency reserve

without understanding the risk.

CAC and Break-Even

Your business needs enough:

gross profit after acquisition cost

to cover:

• overhead.

If acquisition cost rises:

break-even economics can worsen.

CAC and Pricing

Higher prices can improve customer gross profit and allow sustainable acquisition spend.

But only if:

• conversion;
• demand

remain healthy.

Pricing and marketing economics are connected.

CAC and Gross Margin

If you improve gross margin:

same customer becomes more valuable.

Example:

Job revenue:

£1,000

35% Margin

Gross profit:

£350

CAC:

£150

Profit after acquisition:

£200

45% Margin

Gross profit:

£450

Same CAC.

Remaining:

£300

Margin improvements increase marketing flexibility.

How to Reduce CAC Without Cutting Marketing

There are several ways.

1. Improve Lead Conversion

Same leads.

More customers.

CAC falls.

2. Answer Calls Faster

Fewer leads wasted.

3. Improve Website Conversion

More visitors become inquiries.

4. Improve Lead Quality

Better targeting.

5. Improve Quote Follow-Up

More estimates convert.

6. Reduce No-Shows

More bookings become paying customers.

7. Improve Reviews

Better trust can improve conversion.

8. Improve Referral Rate

Lower-cost acquisition source.

Do Not Slash Marketing Just Because CAC Rises

First ask:

why.

CAC may rise because:

• seasonality;
• competition;
• lower conversion.

Cutting marketing without analysis can reduce revenue further.

Find root cause.

Common CAC Mistakes

Using Leads Instead of Customers

That calculates CPL, not CAC.

Ignoring Sales Costs

Fully loaded CAC becomes understated.

Mixing Repeat and New Customers

Makes acquisition look cheaper.

Using Revenue Instead of Gross Profit

Customer value becomes overstated.

Ignoring Channel Differences

Blended average hides weak campaigns.

Optimizing Only for Cheap Leads

Cheap leads can be low quality.

Ignoring Repeat Business

Lifetime value is underestimated.

Ignoring Capacity

Marketing creates more work than technicians can handle.

Ignoring Cash Flow

Profitable marketing can still create short-term cash pressure.

Using One Month of Data

Small samples can be misleading.

Customer Acquisition Cost Checklist

Track:

• Marketing spend
• Sales costs where relevant
• Lead count
• Cost per lead
• Bookings
• New paying customers
• CAC
• CAC by channel
• Lead conversion rate
• Average first-job revenue
• Average first-job gross profit
• Repeat purchase rate
• Customer lifetime value
• LTV:CAC
• CAC payback
• Technician capacity
• Cash-flow impact

Sources and Further Reading

These official resources back up the methods in this guide and are worth reading alongside it.

• Marketing and sales (U.S. Small Business Administration): planning and measuring marketing for a small business.
• Manage your finances (U.S. Small Business Administration): bookkeeping, financial statements and cash flow basics.

Related guides

• How to Build Service Pages That Rank on Google in 2026
• Local SEO for Trades: A Practical Small-Business Guide
• Best Local SEO Tools for Service Businesses in 2026: 6 Tools Compared
• Tools, Software and Automation for Trades: Start Here

Frequently Asked Questions

What is customer acquisition cost?

Customer acquisition cost measures how much money a business spends to acquire a new customer.

How do you calculate CAC?

Use:

Sales + Marketing Costs ÷ New Customers Acquired

Is CAC the same as cost per lead?

No.

Cost per lead measures how much it costs to generate an inquiry.

CAC measures how much it costs to generate an actual new customer.

What is a good CAC for a service business?

There is no universal number.

CAC should be evaluated relative to:

• gross profit;
• lifetime value;
• payback period.

Should SEO costs be included in CAC?

They can be included when calculating organic acquisition cost or blended CAC.

Should sales salaries be included?

For fully loaded CAC, yes, where those sales costs relate to customer acquisition.

Is lower CAC always better?

No.

A higher-CAC customer may produce much more:

• gross profit;
• lifetime value.

How can I reduce CAC?

Improve:

• lead quality;
• conversion;
• call handling;
• quote follow-up;
• customer reviews.

Why should CAC be compared with gross profit instead of revenue?

Revenue does not account for the cost of delivering the service.

Gross profit gives a more realistic picture of customer value.

How often should CAC be reviewed?

Monthly is useful for many businesses, while longer rolling periods can help smooth volatility.

Conclusion

Understanding customer acquisition cost for a service business turns marketing from:

“How many leads did we get?”

into:

“How much did it cost us to acquire a profitable customer?”

Start with:

Marketing + Sales Cost

↓

Leads

↓

Bookings

↓

New Customers

↓

CAC

Then connect CAC to:

First-Job Gross Profit

↓

Repeat Business

↓

Customer Lifetime Value

For example:

Marketing spend:

£12,000

New customers:

80

CAC:

£150

If average lifetime gross profit is:

£1,100

that may be very healthy.

But if average customer gross profit is only:

£200

the same £150 CAC may be difficult to sustain.

That is why:

cheap leads are not the goal.

Profitable customers are.

Use CAC to improve:

• marketing channels;
• lead handling;
• pricing;
• capacity planning;
• budgeting.

And always remember:

marketing should not be judged only by:

how much revenue it produces.

It should be judged by:

how much profitable customer value it creates after the cost of acquisition.