This checklist is the standard Ready to Calculate uses before treating a calculator as healthy. It is intentionally practical: load, tap, calculate, resize, and verify the source note.
Calculator health checklist
- Page loads with the site header and footer visible.
- Default result appears on load, or the tool clearly asks for input before calculating.
- Changing each input updates the result.
- Calculate / reset / download / share buttons work.
- Mobile width does not create horizontal scroll.
- Inputs are at least 44px tall on mobile.
- Copy result and Share calculator buttons work where shown.
- Source note and Last updated line are visible on calculator pages.
- No browser console errors after first interaction.
- FAQ and related calculators are present where useful.
Priority tools to test after every site change
- UK Take Home Pay Calculator
- UK Side-Hustle Tax Calculator
- UK IR35 Calculator
- UK Dividend Tax Calculator
- UK Marriage Allowance Calculator
- AI Subscription Cost Calculator
- LLM Token-to-Cost Calculator
- PC Bottleneck Calculator
- Wedding Budget Calculator
When a calculator fails
If a calculator fails, fix reliability before visual polish. The usual causes are delayed JavaScript, missing helper functions after legacy cleanup, IDs changed in markup, or a third-party script being blocked.