Dates & Time

Age · Korean Age Calculator · Date Duration

Age Calculator

Calculate your exact age in years, months, and days. Find out how many total days, weeks, hours, and minutes you have lived — plus how many days until your next birthday.

Buddhist Calendar Converter

Convert dates between the Gregorian calendar (CE) and the Thai Buddhist Era calendar (BE). Handles the pre-1941 Thailand reform automatically.

Chinese Lunar Calendar Converter

Convert any date between the Gregorian calendar and the Chinese, Vietnamese, or Korean lunar (lunisolar) calendar. See the zodiac animal, sexagenary year, element, solar term and leap-month status instantly.

Date Duration Calculator

Calculate the exact duration between two dates and times. Get results in years, months, days, hours, minutes, and seconds.

Hebrew Calendar Converter

Convert dates between the Hebrew (Jewish) and Gregorian calendars. Includes Adar I/II in leap years and upcoming festival countdowns.

Hijri Calendar Converter

Convert dates between the Hijri (Islamic) lunar calendar and the Gregorian calendar. Shows AH year, Ramadan and Eid countdowns, and Arabic-Indic numerals.

Japanese Era Converter

Convert dates between the Gregorian calendar and the Japanese era calendar (wareki) across Meiji, Taisho, Showa, Heisei and Reiwa. Day-exact era resolution, gannen handling, and the Japanese-script date ready to copy.

Korean Age Calculator (Man nai, Se-neun nai, Yeon nai)

Calculate your Korean age in all three systems — Man nai (legal, since 2023), Se-neun nai (traditional) and Yeon nai (year age) — from a single date of birth.

Old Style / New Style Date Converter

Convert a date exactly as a historical document writes it — Julian or Gregorian, Lady Day or 1 January, double-dated or numbered — into every other reading of the same day.

Persian Calendar Converter

Convert any date between the Persian (Solar Hijri, Jalali, Shamsi) calendar and the Gregorian calendar, in both directions.

Pet Age Calculator — Dog & Cat Years in Human Years

Convert your pet's age into human years using veterinary life-stage data, not the ×7 myth. Dogs by size class, cats, horses and five small pets, in both directions.

Time Converter

Convert time between nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days, weeks, fortnights, months, years, and decades. Exact SI factors, honest Julian month and year conventions.

World Calendars Converter

Convert any date across six world calendar systems at once: Gregorian, Hijri, Hebrew, Persian, Japanese Era, and Buddhist.

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Dates & Time

Every calculator in this category, free and with no sign-up:

Age · Korean Age Calculator (Man nai, Se-neun nai, Yeon nai) · Date Duration · Pet Age Calculator — Dog & Cat Years in Human Years · Time Converter · Buddhist Calendar Converter · Hijri Calendar Converter · Persian Calendar Converter · Old Style / New Style Date Converter · Hebrew Calendar Converter · Chinese Lunar Calendar Converter · World Calendars Converter · Japanese Era Converter

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Frequently Asked Questions

Are these calculators free?

Yes. Every calculator on this page runs in your browser, is free to use and needs no account.