Time Converter — Free
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Every duration has a favorite unit: workouts count minutes, flights count hours, and computers count milliseconds. Type a value into any one of the ten units and the other nine fill themselves instantly, plus a plain-English line that reads any span as days, hours, minutes, and seconds.
How it works
- 1
Pick a unit
Start from nanoseconds, seconds, hours, years — whichever unit you already have.
- 2
Type the value
All nine other units update on the same keystroke.
- 3
Read the plain-English line
The result spells the span out as days, hours, minutes, and seconds.
About this tool
How the units relate
Every conversion runs through the second: a minute is 60, an hour 3,600, a day 86,400, and a week 604,800 of them. Below the second, each step down divides by a thousand — milliseconds, microseconds, nanoseconds. Those factors are exact, so any conversion between them is exact too. Months and years use the calendar average (a 365.25-day year), because real calendar months run from 28 to 31 days.
Converting durations is not the same as counting days between dates
Unit conversion multiplies a length of time by a fixed factor; measuring the gap between two calendar dates counts real days, including the leap years that fall between them. For durations, use this tool; for calendar gaps, use the date and time difference calculator. And if you have a timestamp rather than a span, the date and time converter turns it into a real date.
Reference points worth memorizing
One million seconds is about 11.6 days; one billion seconds is about 31.7 years — a useful gut check whenever a countdown or a log duration looks absurd. A blink takes around 300 milliseconds, a typical keystroke 250, and light circles the Earth in about 134 milliseconds.
Frequently asked questions
How many seconds are in an hour?
3,600 — 60 seconds per minute times 60 minutes per hour. Multiply hours by 3,600 (or read the seconds row here) for any number of hours.
How long is one billion seconds?
About 11,574 days — roughly 31.7 years. It is the classic reminder that "a billion" is far bigger than "a million": one million seconds is under two weeks.
Are the month and year conversions exact?
They use the calendar average: a 365.25-day year and a month of one twelfth of it. Real months vary from 28 to 31 days, so converting a specific calendar span month by month is date math, not unit math.
What is the difference between a millisecond and a microsecond?
A millisecond is one thousandth of a second; a microsecond is one millionth. A blink spans hundreds of milliseconds, while fast computer operations are measured in microseconds and below.
Can I convert fractional values?
Yes — type 2.5 hours and the day row reads about 0.104 days. Fractions carry through every unit at full precision.