About JapanCalc
JapanCalc is a free, bilingual (Japanese and English) collection of 28 calculators and converters for everyday life in Japan — take-home pay, Japanese era dates, postage, katakana names and more. It is used by people living and working in Japan, visitors, and Japanese learners.
Who runs JapanCalc
JapanCalc is an independent website. It is not affiliated with any government office, municipality, Japan Post or other official body. Results are estimates based on official published figures; for formal procedures, always confirm with the relevant authority.
How we keep the numbers right
- Every tax rate, insurance rate and fee the tools use comes from an official source. Each calculator page names its sources and when they were last checked, under How This Is Calculated — Sources.
- Figures are re-checked on a schedule: tax and social insurance every April (the start of the Japanese fiscal year), statistics when they are published, postage when Japan Post announces a revision, and public holidays when the Cabinet Office confirms the next year.
- Before every update, the numbers written in the page text are checked automatically against what the calculator itself returns, so the explanation and the result cannot quietly drift apart.
- When an error is found, it is fixed and the main corrections are published with dates.
See every source, last-checked date and correction in the verification log ›
All tools
Tax & Money（10）
- Compound Interest Calculator — Savings & compound interest simulator
- Mortgage Calculator — Calculate monthly mortgage payments
- Bill Splitting Calculator — Split bills Japanese warikan style
- Postage Calculator — Japan Post mailing cost calculator
- Furusato Nozei Calculator — Calculate tax deduction limit
- Discount Calculator — Calculate discount prices
- Consumption Tax Calculator — Add or remove 10% / 8% tax
- Salary Calculator — Estimate net take-home pay
- Overtime Calculator — Calculate overtime pay
- Withholding Tax Calculator — Calculate withholding tax
Dates & Calendar（11）
- Business Days Calculator — Calculate business days excluding holidays
- Shichi-Go-San Calculator — Find your child's 753 ceremony years
- BMI Calculator — BMI & ideal weight, Japan standard
- Yakudoshi Calculator — Find your bad luck years
- Days Between Dates — Calculate days & business days
- Kazoe-doshi Calculator — Traditional Japanese age
- Era Date Converter — Convert Reiwa, Heisei, Showa
- Japanese Age Calculator — Calculate 満年齢 and 数え年
- Japanese Zodiac Calculator — Find your eto animal sign
- Japan Holiday Checker — Check public holidays
- Travel Budget Calculator — Estimate Japan trip costs
Language & Conversion（7）
- Password Generator — Generate secure passwords instantly
- Japan Area Converter — Convert tsubo, tatami, sqm
- Character Counter — Count characters in real time
- Romaji Converter — Convert Japanese to romaji
- Katakana Name Converter — Write your name in Japanese katakana
- Kanji Number Converter — Arabic ↔ Kanji numbers
- Measurement Converter — Height, weight & size converter
Privacy
Everything you type into a calculator is processed in your browser and never sent to a server. To improve the site, anonymous usage statistics (which pages are viewed, how often a tool is used) are measured with Google Analytics 4. Details are in the privacy policy.
Contact and error reports
Found a wrong number, or a result you are not sure about? Email [email protected]. Including the page URL and the values you entered makes it much quicker to check.