How We Calculate?
Last updated: October 3, 2026
A calculator is only useful if you can trust the number. This page explains how I build the calculators on HowCalculate.com, where the figures come from, and how I keep them correct.
Where do the formulas come from?
Every calculator uses a standard, widely accepted definition. For example, CPM (cost per mille) is total ad cost divided by impressions, multiplied by 1,000. The formula is shown on each calculator’s page, along with worked examples, so you can check the math yourself and use it in a spreadsheet if you like.
How do I test each calculator?
Before a calculator goes live, I work out several examples by hand and check that the tool gives exactly the same answers. A simple case looks like this: $500 for 80,000 impressions should give a CPM of $6.25. I also test empty fields, zero values and very large or small numbers, and I check that the page works on a phone.
What happens to the numbers you enter?
The calculators run in your browser. The figures you type in are worked out on your own device and aren’t sent to me or stored.
How do I handle fees?
Fee calculators depend on rates that platforms set and change. For those, I:
- Use the platform’s own official pricing page as the source.
- Show the date I last verified the rates on the calculator page.
- Recheck them at least every three months, and sooner when I hear that a platform has changed its pricing.
Some fees depend on your country, account type, or payment method, and a calculator can’t cover every case. Where a tool makes an assumption, such as standard US rates, the page says so.
How do I handle benchmarks?
Benchmarks, such as typical advertising costs on a platform, come from named, published sources, and I show where they came from. These figures vary a lot between sources and change over time. When sources disagree, I say so and give a range instead of picking a single tidy number. I treat benchmarks as rough guides, not targets.
What don’t I do?
- I don’t invent statistics or benchmarks.
- I don’t copy text or numbers from other sites.
- I don’t let advertisers influence results or recommendations.
Rounding and limits
Results are rounded for readability, usually to two decimal places, so they can differ slightly from what a platform reports. A calculator gives an estimate based on your inputs. It doesn’t know your taxes, contracts, or account details, and it isn’t financial or professional advice. See the Disclaimer for more.
Who writes and reviews the content?
All content on this site is written and reviewed by Ajay Kumar, an SEO strategist and content writer. You can read more on the About page.
Found a mistake?
If a result, formula, fee, or benchmark looks wrong, please tell me. Email howcalculate@gmail.com with the page address and what you expected to see. I’ll check it, fix it if you’re right, and update the date on the page.