Ad Budget Calculator

Most advertising decisions start with the wrong question: “how much should I spend?” A better one is “how much can I afford to pay for a customer, and what will one actually cost me?” Answer those two and the budget follows. This calculator does the sums from your own numbers.

The figures filled in are examples to show how it works. They are not industry averages, and your own results could be very different.

How the calculation works

There are two halves: what you can afford, and what you are likely to pay.

• Most you can pay per customer = customer value × gross margin × the share of that profit you’re willing to spend.
• Click-to-customer rate = % of clicks that enquire × % of enquiries that become customers.
• Clicks needed = customers wanted ÷ click-to-customer rate.
• Monthly budget = clicks needed × cost per click.
• Actual cost per customer = cost per click ÷ click-to-customer rate.

If the actual cost is at or below the most you can pay, the campaign can pay for itself. If not, it shows what would have to change.

Using the example figures as an illustration: a £400 customer at a 50% margin leaves £200 profit, and 30% of that is £60. If 8% of clicks enquire and 30% of those buy, 2.4% of clicks become customers. Ten customers then need 417 clicks; at £1.20 a click that is about £500 a month, or £50 a customer, inside the £60 limit.

Where do I find each number?

• Customer value. Use the average first sale from your sales records. Only use lifetime value if you know how often customers come back and for how long; otherwise you risk overspending on a guess.
• Gross margin. Price minus the direct cost of delivering the sale (materials, stock, subcontractors), as a percentage of price. Your accountant or your accounts will have it.
• Share you’ll spend. A business decision, not a rule. A lower share leaves more profit; a higher one wins more customers but with less to spare.
• Cost per click. Your past campaigns are the best guide. If you have none, Google’s Keyword Planner shows the average cost for an ad to show on searches for a keyword.
• Enquiry and conversion rates. From your website analytics and your own records: how many visitors got in touch, and how many of those became paying customers.

How to read the result

The verdict compares your actual cost per customer with your limit. When it’s too expensive, there are three levers. You can lower the cost per click with narrower, more specific targeting. You can lift conversion with a clearer landing page and faster replies. Or you can raise what a customer is worth, through repeat business or a better offer. The levers multiply, so a modest improvement in two of them often beats a big push on one.

Remember the limits. The calculator counts ad spend only, not agency fees or your time. Rates change month to month. Treat the result as a starting point, run a small test, then replace the inputs with what actually happened.

What to do next

• Start small. Spend enough to get real click and enquiry numbers, then rerun the calculator.
• Track every enquiry back to its source, or you can’t tell which ads paid.
• Fix the free channels first. Our guide on advertising on Google for free covers what to do before paying for clicks.
• Set the overall budget with the marketing budget calculator and our guide to how much to spend on marketing.

The get found and chosen guides and the free template packs cover the rest.

Questions people ask

What is a good cost per customer for a small business?

There is no single right figure. It depends on what a customer is worth to you and your margin. A £60 limit can be generous for one business and far too low for another, which is why the calculator starts from your own numbers.

Should I use first-purchase value or lifetime value?

Start with the first purchase unless you have records showing how often customers return and for how long. Lifetime value gives a higher limit, but if you overestimate it you pay for customers who never earn it back.

What if I don’t know my conversion rates yet?

Run a small test first. Spend a modest amount, count the clicks, enquiries and sales it produces, then put those real figures into the calculator. A guess at conversion rates can easily be far off, in either direction.

Why might my real cost per customer be higher?

The calculator counts ad spend only. Agency or management fees, your own time, and the cost of handling enquiries that never buy are extra. Small tests also give unreliable rates, so check again once you have more data.

Test before you spend with Techhound

Techhound’s Audience Simulator lets you show an ad to a simulated panel of UK or US consumers or business decision-makers and get scores, objections and a verdict before you spend on clicks. It is a rehearsal, not a replacement for real customers. Its growth plan also includes a marketing P&L with customer acquisition cost, lifetime value and payback months, using plain arithmetic you can change.