Seven calculators for pricing, growth and measurement — margin and markup, VAT and tax bands, month-on-month growth, A/B test significance, weighted averages, and what an LLM API or marketplace listing really costs. All calculations run locally in your browser, with no sign-up.
Which one do I need?
Common questions
What's the difference between margin and markup?
Margin is profit as a percentage of the selling price; markup is profit as a percentage of the cost price. The same £10 profit on a £40 cost is a 20% margin but a 25% markup — the margin vs markup calculator converts between them so you're never quoting the wrong one.
How is statistical significance worked out for an A/B test?
The calculator runs a two-proportion z-test between your control and each variant, converting the conversion-rate difference into a z-score and p-value, so you can see whether an uplift is likely real or within normal noise.
Does the AI cost calculator account for prompt caching?
Yes — it separates cached and uncached input tokens plus output tokens at each price, and includes the batch-API discount where a provider offers one, since caching materially changes the real cost of repeated prompts.