Last Updated on October 21, 2026
Most marketing ROI sums use revenue, and revenue flatters. An agency report saying “4x return” can sit on top of a monthly loss once your margin is applied. This calculator does the sums the way your accountant would: on gross profit. Type your numbers, get your break-even point, cost per customer and margin-true ROI.
No email address, no sign-up. Everything runs in your browser and nothing you type is sent anywhere.
This calculator needs JavaScript. The method is described below, and the arithmetic is simple enough to do on paper.
How the sums work
Three steps, no secret weighting.
Contribution per sale = average sale value x gross margin. This is what a sale actually leaves behind.
Break-even = monthly marketing spend divided by contribution per sale. That many sales a month and the spend has paid for itself. If you sell through enquiries, dividing again by your close rate gives the enquiries you need.
Margin-true ROI = (monthly gross profit from marketing minus the spend) divided by the spend. Margin-true ROI is the return on marketing spend measured on gross profit rather than revenue. A campaign that returns four times its cost in revenue is losing money whenever the gross margin is below 25%. That single check catches more bad retainers than any dashboard.
Every figure in the results is your own input run through this arithmetic. The calculator uses no industry averages and no estimates, because your margin and close rate are the only numbers that matter here and only you have them.
Who this is for
UK businesses paying for marketing and unsure whether it pays back. It suits a trades business counting enquiries, a firm counting won clients, and a shop counting orders. If you are setting the budget rather than judging it, use the UK marketing budget planner first.
Questions people ask
What is margin-true ROI?
Margin-true ROI is the return on marketing spend measured on gross profit rather than revenue. A 4x revenue return at a 20% margin is 0.8x in gross profit, which is a 20% loss on the spend.
Why not use revenue like other calculators?
Because you cannot bank revenue. Agencies report revenue multiples because they are bigger numbers. Your accounts run on margin, so your marketing judgement should too.
What counts as marketing spend here?
Everything that stops if you stop marketing: provider fees, ad spend, software, freelance content. Using fees alone flatters the result.
Is my data stored?
No. The arithmetic runs in your browser. Nothing is sent to Whito or any third party.
What is a good close rate or cost per enquiry?
We do not publish one, because credible UK-wide figures by trade do not exist at a sample size we would trust. Judge your own numbers month on month instead.
