Time Duration Converter

How It Works

This time converter uses the second (s) as its base unit, which is the SI base unit for time. Every other time unit stores a factor equal to its number of seconds. Converting from hours to minutes, for example, multiplies by 3,600 (seconds per hour) then divides by 60 (seconds per minute) to arrive at 60 minutes.

The second itself is now defined with extreme precision: since 1967, one second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom. Atomic clocks based on this definition are accurate to about 1 second in 300 million years.

Calendar time units — months and years — are approximations because they vary:
• The average Gregorian calendar month = 365.2425 days ÷ 12 = 30.436875 days = 2,629,746 s.
• The mean tropical year (time for Earth to orbit the sun) = 365.24219 days = 31,556,926 s.
• This converter uses 31,556,952 s for a year (the Julian year of exactly 365.25 days), a common scientific convention.

For precise calendar calculations involving specific dates, use a dedicated date-difference tool. This converter is appropriate for approximate conversions of durations (e.g., "roughly how many seconds in a year?").

Worked example — How many seconds in a year?
1 yr × 31,556,952 s/yr = 31,556,952 s ≈ 31.6 million seconds.
A common approximation: π × 10⁷ ≈ 31,415,927 s — accurate to within 0.5%.

Worked example — Software timing:
A web server response of 250 ms = 0.25 s = 250,000 µs = 250,000,000 ns. Browser performance budgets target 16.67 ms per frame (60 fps) — that is 16,666,667 nanoseconds.

Worked example — Project planning:
18 months = 18 × 2,629,746 s ÷ 86,400 s/day = 547 days ≈ 78.1 weeks.

Worked example — Historical timescales:
The Roman Empire lasted roughly 500 years in the West. In days: 500 × 365.25 = 182,625 days.

Nanosecond (ns) and microsecond (µs) conversions are particularly relevant in electronics, networking, and computing. CPU speeds in GHz mean operations happening billions of times per second — at 3 GHz, each clock cycle is about 0.33 ns.