Time Unit Converter: seconds, minutes, hours, days, weeks, months and years

How it works

seconds = value × seconds per “from” unit · result = seconds ÷ seconds per “to” unit · 1 min = 60 s · 1 h = 3,600 s · 1 day = 86,400 s · 1 week = 604,800 s · 1 year = 365.25 days (or 365.2425 or 365) · 1 month = 1/12 year

Every conversion goes through the second, the SI base unit of time. The units up to a week are exact: 60 seconds in a minute, 60 minutes in an hour, 24 hours (86,400 seconds) in a day and 7 days in a week. A fortnight is 14 days. Months and years vary on a real calendar, so they need a fixed definition. By default this converter uses the Julian year of 365.25 days (31,557,600 s), the average that includes a leap day every four years and the year astronomers use. Under More options you can switch to the Gregorian calendar average of 365.2425 days, or to a common 365-day year (31,536,000 s), which is what many simple converters use. A month is always one twelfth of the chosen year, about 30.44 days by default. Decades, centuries and millennia are 10, 100 and 1,000 years. The result also shows the conversion factor, the amount in seconds, a days-hours-minutes-seconds breakdown and the same amount in every unit. Use averages for planning, not for counting exact days between dates.

Worked example

Convert 1 hour to minutes: 1 × 3,600 s = 3,600 s, then 3,600 ÷ 60 = 60 min. With the default 365.25-day year, 1 year = 365.25 × 86,400 = 31,557,600 s; with a 365-day year it is 31,536,000 s.

Sources: NIST Guide to the SI, Appendix B.9: conversion factors for time · CalculatorSoup: Time conversion calculator

Frequently asked questions