Time converter — seconds, minutes, hours, days, weeks and years

How to use the time converter

1. Type a duration in Value, for example 90.
2. Select the unit it is in from From, such as minutes.
3. Select the unit you want from To. The answer updates as you type.
4. Read the table for the same duration in every unit, from nanoseconds to centuries.
5. The swap button reverses the conversion.

What it does and when to use it

The tool converts durations between 14 units: nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days, weeks, 30-day months, 365-day years, Gregorian years, Julian years, decades and centuries.

It is useful for turning a video length or a timer reading into minutes, checking how many hours a project estimate in weeks really is, reading a server timeout given in milliseconds, or for “how long is a billion seconds?” questions. Shift workers often need minutes as decimal hours for a timesheet, which this does directly.

For a real span between two calendar dates, including leap years and different month lengths, use the date difference calculator. To time something live, the stopwatch runs in the browser.

How it works

Every unit is a fixed number of seconds:

• minute = 60 s; hour = 3,600 s; day = 86,400 s; week = 604,800 s
• month = 30 days = 2,592,000 s
• year = 365 days = 31,536,000 s
• Gregorian year = 365.2425 days; Julian year = 365.25 days
• decade = 10 × 365 days; century = 100 × 365 days

Seconds through weeks are exact. The month, year, decade and century options are conventions for estimates, and the tool shows a note saying so under each result. The Gregorian figure comes from the leap-year rule: a leap day every four years, except in century years, unless the century divides by 400.

Worked examples

Each result is the converter’s own output.

A film’s running time. 90 minutes = 1.5 hours.

A two-week sprint. 2 weeks = 336 hours of calendar time. At 40 working hours a week, the working time is 80 hours, so check which figure an estimate means.

A billion seconds. 1,000,000,000 seconds = 31.7097919838 years using 365-day years, or 31.6887385068 Gregorian years once leap days are counted. Either way, it is about 31 years and 8 months.

Limits and tips

• Clock format is not accepted. Enter 2:30 as 2.5 hours or 150 minutes.
• Leap seconds are ignored; a day is always 86,400 seconds here.
• Long spans drift. Using 365-day years over a century leaves you about 24 days short of the real calendar.
• For speeds that mix distance and time, use the speed converter.