Time Converter
Enter a value to instantly convert between time units.
Time conversions are some of the most universally familiar — everyone has converted hours to minutes or days to weeks — but they're also needed for more specialized tasks like calculating project durations in working days, converting scientific measurements involving milliseconds or microseconds, or figuring out exactly how many days are in a given number of years for age or interest calculations. Unlike most categories on this site, time units don't follow a single consistent base (some units are powers of 10 apart, others — like hours to days — are not), which is a quirk worth understanding.
1 Hour = 60 Minute
Key Formulas
Hour → Minute
min = h × 60Minute → Hour
h = min × 0.0166667Day → Hour
h = d × 24Hour → Day
d = h × 0.0416667Popular Conversions
Choose Any Time Units
Choose any two time units in the converter above. Dedicated conversion guides appear here only after their formulas and supporting content have been reviewed.
About Time Conversions
History & Background
The division of the day into 24 hours and the hour into 60 minutes traces back to ancient Babylonian and Egyptian astronomy, which used a base-60 (sexagesimal) numbering system — a convention so deeply embedded that it has survived essentially unchanged for thousands of years, unlike almost every other measurement system, which has been metricated. The second, now the SI base unit of time, was originally defined as a fraction of the day (1/86,400) but has since been redefined in terms of atomic clock oscillations for extreme precision — a definition completely decoupled from its historical origin as 'a small fraction of a day,' even though the numerical relationship (86,400 seconds per day) remains unchanged for everyday purposes.
How to Use This Converter
Select your starting and target time units and enter a value for an instant conversion. Because units like years contain a fractional number of days (365.25, accounting for leap years), conversions involving years use an averaged value — for precise date-based calculations (e.g., 'exactly how many days between these two dates'), a calendar-based calculation rather than a unit conversion is more appropriate.
Frequently Asked Questions
Why does a year not convert to a round number of days?
A calendar year is approximately 365.25 days (which is why a leap day is added roughly every 4 years) — so any conversion involving years uses this averaged figure rather than exactly 365, to remain accurate over long periods. For a specific calendar year, the actual number of days is either 365 or 366 depending on whether it's a leap year.
What are milliseconds, microseconds, and nanoseconds used for?
These very small time units are common in computing, electronics, and physics — a computer processor might execute an instruction in nanoseconds, while network latency is often measured in milliseconds. They follow the standard metric prefix pattern (milli = 1/1,000, micro = 1/1,000,000, nano = 1/1,000,000,000 of a second), unlike the hour/day/week/year relationships, which don't follow powers of 10.
How many seconds are in a day, and why does that number matter?
There are 86,400 seconds in a day (24 × 60 × 60). This number appears throughout science and computing — for example, it's the basis for converting between data transfer rates measured per second and totals measured per day, and it's a useful figure to have memorized for quick estimates involving daily totals.