About
This is a free collection of online calculators: 100 tools across finance, health, math and everyday utilities, available in Simplified Chinese and English. Every calculation runs locally in your browser — no account, no sign-up.
Who runs this site
The site is maintained by a small independent editorial and development team. We are not a medical provider, a financial institution or a law firm. The motivation is simple: make common calculations accurate, explain them clearly, and keep them free.
How the content is produced
- Establish the formula and standard: each calculator starts from a published formula and its source (e.g. WHO BMI bands, Mifflin-St Jeor, US Navy / US Army body-fat equations, MDRD for GFR, standard amortization).
- Implement and verify: the logic is written as pure functions with automated tests covering edge cases such as division by zero, negative inputs and empty values.
- Explain it: every page states the formula, assumptions, limitations and common questions — not just an input box.
- Bilingual review: the Chinese and English versions are checked line by line so translation does not shift the meaning.
How we keep it accurate
Calculation logic is covered by unit tests, and every formula is published in the “How it works” section so you can check it yourself. If you find an error, please tell us; we verify and correct it, and note the update date on the page.
What we do not do
- We do not provide personalised medical, investment, legal or tax advice.
- We do not replace a doctor, dietitian, financial adviser or lawyer.
- We do not sell user data or ask you to submit personal health information.
Updates
Formulas and explanations are reviewed periodically, and page dates are updated when something material changes. Our guides are expanded over time to cover more real-world cases and common mistakes.
Contact
Email: contact@calculator.org.cn. We usually reply within a few business days.