People rely on ToolHa to get numbers right, whether for homework, work, travel, training or planning. This page explains exactly how each tool is made, checked and kept up to date, so you can judge for yourself how far to trust a result.
Our standard in one minute
- Every result is based on a published definition or an official source.
- Every tool is tested against known answers and edge cases before it goes live.
- Results appear instantly, on any phone, tablet or computer.
- Every page is reviewed by a person, and corrections are our top priority.
1. Start from real questions
Before building a tool we study what people actually need: the questions they search for, the follow-up questions they ask, and the mistakes they commonly make. A good tool answers the question in one step and the next question in the second.
2. Use published definitions and official sources
Every conversion and calculation starts from a recognised definition. For example, the international mile is defined as exactly 1,609.344 metres and the pound as exactly 0.453 592 37 kilograms. Tools that depend on local rules (tax, holidays, fees or land units) name their source and show the date the facts were last checked.
3. Test before anything goes live
- Known answers: results are compared with worked examples from the source and with independent references.
- Edge cases: zero, very large and very small values, decimals, negative numbers where they make sense, and empty inputs.
- Rounding: we check that rounding never hides a meaningful difference, and show more decimals when you need them.
- Devices: every tool is checked on phones and computers, in light and dark mode, and with a keyboard.
4. Fast on any device
Results appear as you type, and every tool works the same on phones, tablets and computers. If a tool needs our server to do its job, its page says so clearly.
5. Explain, not just answer
Calculators show the formula and the steps behind each result. Guides add tables, worked examples and common mistakes, so you can understand the answer and check it yourself, not just copy it.
6. Checked before it goes live
The help text on each page is written to be clear for a global audience. Before a guide is published, someone on the team checks it against the sources and against the live tool, and the numbers in tables are generated by code rather than typed by hand.
7. Kept up to date
Rules change, especially tax rates, public holidays and fees. We review time-sensitive tools regularly and whenever an official source changes, and update the “last checked” date when we do.
Found a problem?
Please tell us through the “Help us make this tool better” box on any tool page, or through our contact page with the topic “Report a problem”. Include the tool name, what you entered and what you expected. Confirmed errors are fixed as a priority.