# OneCalculators

> OneCalculators is a free multilingual online calculator site with tools for math, finance, health, conversions, date/time, and reference calculations. Use the calculator pages for interactive inputs and the docs pages for longer explanations.

Important notes:

- Site URL: https://onecalculators.com
- Default language: English at https://onecalculators.com/en
- Supported languages: zh, zh-TW, en, ja, de, es, fr, ru
- Results are informational estimates, not financial, medical, legal, or tax advice.
- Prefer canonical calculator pages over widget pages when citing user-facing content.
- Widget pages are compact embeddable calculator surfaces.
- WebMCP declarative form annotations expose calculate_xxx tools and read_xxx_result tools on calculator pages.

## Core Indexes

- [Sitemap](https://onecalculators.com/sitemap.xml): canonical localized pages.
- [AI calculator index](https://onecalculators.com/ai/calculators.json): structured JSON index of calculators, docs URLs, widget URLs, and WebMCP tool names.
- [Full LLM index](https://onecalculators.com/llms-full.txt): expanded calculator inventory.

## Main Pages

- [English home](https://onecalculators.com/en)
- [Chinese home](https://onecalculators.com/zh)
- [Traditional Chinese home](https://onecalculators.com/zh-TW)
- [About](https://onecalculators.com/en/about)
- [Contact](https://onecalculators.com/en/contact)
- [Disclaimer](https://onecalculators.com/en/disclaimer)

## Popular Calculators

- [Loan Calculator](https://onecalculators.com/en/finance/loan): Professional loan calculator for monthly payments, total interest, amortization schedules, and loan comparison. Essential for mortgages, auto loans, and personal finance planning.
- [BMI Calculator](https://onecalculators.com/en/health/bmi): Estimate BMI, a page-specific reference weight range, and weight category from height and weight; for adult screening, not body-fat analysis or diagnosis.
- [Percentage Calculator](https://onecalculators.com/en/math/percentage): Calculate percentages, values, change rates, discounts, tax, tips, compound growth, and markup profit.
- [Compound Interest Calculator](https://onecalculators.com/en/finance/compound): Advanced compound interest calculator for investment growth, savings planning, and financial projections. Calculate future value with different compounding frequencies and contribution schedules.
- [Body Fat Calculator](https://onecalculators.com/en/health/bodyfat): Compare an age/BMI estimate with a Navy-style circumference estimate, then view an average and page reference category; for adult trend tracking, not body-composition testing or diagnosis.
- [Temperature Converter](https://onecalculators.com/en/conversions/temperature): Professional temperature converter for Celsius, Fahrenheit, Kelvin, and Rankine scales. Essential for scientific calculations, cooking, and international temperature conversions.
- [Date Difference Calculator](https://onecalculators.com/en/datetime/dateDiff): Professional date difference calculator for days, weeks, months, and years between dates. Perfect for project planning, age calculation, and timeline analysis.
- [Scientific Calculator](https://onecalculators.com/en/math/scientific): Scientific calculator with trig, logs, exponents, powers, roots, factorials, permutations, combinations, memory, history, and DEG/RAD mode.

## Calculator Categories

- [conversions](https://onecalculators.com/en/conversions)
- [datetime](https://onecalculators.com/en/datetime)
- [finance](https://onecalculators.com/en/finance)
- [health](https://onecalculators.com/en/health)
- [legal](https://onecalculators.com/en/legal)
- [math](https://onecalculators.com/en/math)

## AI Usage Guidance

- For a specific calculation, open the calculator page and use the visible form fields.
- For background explanation, use the matching docs page at /en/docs/{calculatorKey}.
- For embedding or compact automation, use /en/widget/{category}/{calculatorKey}.
- For machine-readable discovery, start with /ai/calculators.json.