Can Your Business Afford Ads? A Beginner’s Guide

Jump to a calculation

A friend recently asked me how to work out whether ads would make sense for their new business. It was much easier to explain by drawing the numbers.

The business, ME Life, offers small-group outdoor workouts in Marina del Rey, with a first class free. The question is simple: how much can you spend getting someone to try a class and become a paying member?

I would start with the customer, then work backward to the ad.

A real business, an illustrative calculation: all financial figures below are invented. They are not ME Life’s prices, costs or results.

01 / Monthly earnings

What does one customer leave you?

Imagine a member pays $150 a month. You still have to provide the workouts, so start by subtracting what it costs to serve them.

One member · One paid month

Member pays: $150
Less: cost to serve them: − $60
Left in the businessBefore acquisition, overhead and profit: $90per month

Include delivery time, materials, payment fees and other costs that come with the customer. Your time counts, even if you do the work yourself.

For group workouts, filling a spare spot may cost little. Adding another class or coach costs more. Use the costs at the size you plan to grow to.

How do I find the average monthly payment?

Use the average across paying customers, rather than your highest advertised price. Monthly recurring revenue is often called MRR.

Monthly recurring revenue: $3,000
Divided by paying members: ÷ 20
Average payment per member: $150

02 / Customer lifetime

How long will they keep paying?

Suppose the average member pays for six months. There are two different numbers to keep in mind.

Lifetime revenue

$150 × 6 paid months

$900

Everything the member pays.

Left after serving them

$90 × 6 paid months

$540

The starting point for your acquisition budget.

Both may be described as “lifetime value,” or LTV. For an ad decision, use the amount left after serving the customer.

If you are new, retention is an assumption. Try a shorter stay too: three paid months would leave just $270. As you gather evidence, follow customers who joined around the same time and check how many are still paying.

What if I sell a one-time service?

Use the money left from that purchase. Only add repeat purchases when you have evidence to support them.

Customer pays for a job: $150
Less: delivery costs: − $90
Left before acquisition and overhead: $60

03 / Your acquisition budget

Set a limit you can afford.

You need money left to run the business. You also need to earn back your acquisition costs soon enough to keep operating. Set both limits, then use the lower one.

Leave money in the business$270

$540 × 50% available for acquisition

Earn it back within 3 paid months$227.50

Expected contribution after allowing for members leaving

Use this lower limit

Keeping half is a choice for this example, not a universal rule. The three-month limit also allows for some members canceling before then.

Where does the $227.50 come from?

The calculator models a six-month average stay as a one-in-six chance of cancellation each month after the first payment.

Month 1 $90 × all members: $90.00
Month 2 $90 × 5/6 still paying: $75.00
Month 3 $90 × 25/36 still paying: $62.50
Expected contribution per original member: $227.50

This is a simplified model, not a prediction of ME Life’s retention. Annual prepayments, changing prices and collection delays need a more specific cash model. Stripe explains the relationship between churn and customer lifetime.

Next, subtract the other costs of winning a customer: sales follow-up, creative, agency fees or providing free trials. Here, we allow $20 per paying member.

Your ad budget · Per new paying member

Total acquisition limit: $227.50
Less: other acquisition costs: − $20.00
Available for adsThis is a customer budget, not a daily budget: $207.50

Spread the cost of all free trials across the people who eventually pay. Keep these acquisition costs separate from the ongoing cost of serving members.

How does a free trial change the budget?

A trial delays the first payment. In the calculator, enter its length and count the recovery window from the start of the trial.

Recovery window: 3 months
Less: imagined free trial: − 30 days
Time left to earn money: 2 paid months
Expected contribution $90 + $75: $165
Less: other acquisition costs: − $20
Available for ads with this trial: $145

This uses a 30-day planning month, not ME Life’s trial policy. Trial delivery costs still belong in other acquisition costs.

04 / Clicks to customers

Follow the click through to payment.

Requesting a free class is a lead. Some people will not attend; others will attend and decide not to join. Only the people who pay count as acquired customers here.

An imagined test · $2.50 per click

100ad clicks
10class requests
2paying members

100 clicks × $2.50 = $250 ad spend

Now compare two outcomes from that same ad spend.

Within your limit

2 members join

Ads per member $250 ÷ 2: $125
Other acquisition costs: + $20

$145total per member

Below your $227.50 limit.
Worth a small test.

Over your limit

1 member joins

Ads per member $250 ÷ 1: $250
Other acquisition costs: + $20

$270total per member

Above your $227.50 limit.
Improve the economics first.

The click price stayed the same. The number of paying customers changed. That is why cheap inquiries alone do not prove that ads work financially.

We hold other acquisition costs at $20 to isolate the difference. In practice, that cost per paying customer may also rise when fewer trials convert.

05 / Your click price limit

What can you afford to pay for a click?

If two of every 100 clicks become paying members, your customer conversion rate is 2%. Multiply that by your ad budget per customer.

Affordable average cost per click

Ad budget per paying member: $207.50
Multiplied by customer conversion rate: × 2%
Your click price ceilingOnly if the conversion assumption holds: $4.15per click

That is the number to compare with keyword research. A lower conversion rate also lowers the price you can afford.

At 2% conversion $207.50 × 0.02: $4.15
At 1% conversion $207.50 × 0.01: ≈ $2.08

06 / Investment to revenue

If I put money in, what could come out?

Using the $145 total acquisition cost from our two-member example, here is what a larger investment would produce if the same assumptions hold.

Illustrative projection · Revenue arrives over time

Total acquisition investment$1,450

Projected lifetime revenue$9,000

This is revenue, not profit or a guaranteed return.

New paying members $1,450 ÷ $145 acquisition cost: 10
Starting monthly revenue 10 members × $150: $1,500
Lifetime revenue 10 × $150 × 6 average paid months: $9,000
Less: lifetime service costs 10 × $60 × 6 months: − $3,600
Less: total acquisition investment: − $1,450
Left before fixed overhead and tax: $3,950

The $1,450 covers both ads and other acquisition costs. The $9,000 is collected across the customers’ lifetimes, not on the day the ads run.

Find your inputs

Where do the numbers come from?

Customer payment and service costs: Start with prices, the expected mix of purchases and delivery costs. Replace estimates with billing and expense records as they become available.
How long customers stay: Start with a cautious assumption. Follow groups of customers from their first payment to cancellation; new customers who have not left yet do not establish an average lifetime.
Cost per click: Use Google Keyword Planner forecasts with your keywords and location. Look for average CPC, or divide forecast cost by forecast clicks. A historical top-of-page bid range is not your expected average click price.
Clicks that become paying customers: Run a tracked test. Connect ad clicks to inquiries, attendance and payments. A form submission may count as a platform “conversion” before anyone pays; check your conversion actions.
Other acquisition costs: Add trial delivery, sales follow-up, creative and agency costs once. Spread them across the customers you actually win.

For local workouts, “outdoor fitness Marina del Rey” is a starting idea for keyword research, not a proven profitable keyword. Check that your location and class times fit the people searching.

How do I calculate conversion rates from a test?

Clicks that become inquiries 10 requests ÷ 100 clicks × 100: 10%
Inquiries that become customers 2 members ÷ 10 requests × 100: 20%
Clicks that become paying customers 2 members ÷ 100 clicks × 100: 2%

Count each person once at each stage and allow time for the same group to reach payment.

What about click-through rate?

Click-through rate (CTR) is the share of ad views that produce a click. It helps estimate traffic. For cost per customer, you then need the click price and the share of clicks that become paying customers.

CTR = clicks ÷ ad views × 100

From estimate to evidence

Run a small test before scaling.

Set a learning budget.Choose an amount you can afford to lose, a clear offer and a specific audience.
Follow one group through the whole journey.Record spend, clicks, requests, attendance and payments. Allow time for people to decide.
Compare the actual cost with your limit.Two customers from 100 clicks is an early result, not proof that the next 10,000 clicks will behave the same way.
Increase gradually and measure again.Check retention, class capacity and the cost of each additional customer.

The funding case

Show an investor what you have measured.

Once repeated tests support the economics, you can explain what additional capital could fund. For example:

A funding scenario · If the measured economics hold

Acquisition investment: $2,900
Divided by total cost per customer: ÷ $145
Projected new members: 20
Monthly payment per member: × $150
Starting monthly revenueBefore service costs and other expenses: $3,000

A useful pitch shows the tests behind those numbers, how results changed as spending increased, and whether you can serve the additional customers. It also accounts for cancellations, operating costs and the wait before cash comes back.

That is the point of working backward: you know what you can afford, what the ads need to achieve, and what to test next.