Time Unit Converter (years to nanoseconds)

Understanding the time unit converter — concept and principle

This converter turns any duration into every common time unit at once, from nanoseconds to years. It is handy for programming timeouts, lab data, project planning and payroll hours.

How it is calculated

Each unit is stored as a number of seconds. The calculator multiplies your value by the seconds in the "from" unit and divides by the seconds in the "to" unit: result = value × s(from) ÷ s(to).

• 1 ms = 0.001 s, 1 µs = 10⁻⁶ s, 1 ns = 10⁻⁹ s
• 1 minute = 60 s, 1 hour = 3,600 s, 1 day = 86,400 s, 1 week = 604,800 s
• 1 average month = 30.436875 days = 2,629,746 s
• 1 year (365 d) = 31,536,000 s; 1 Julian year (365.25 d) = 31,557,600 s

The principle

The second is the SI base unit of time, defined by fixing the caesium-133 hyperfine transition frequency at exactly 9,192,631,770 Hz. Milliseconds, microseconds and nanoseconds are decimal SI prefixes, so they are exact powers of ten. Minutes, hours and days are a much older sexagesimal (base-60) and base-24 system that is still accepted for use with the SI. Months and years are calendar units, not fixed lengths: a month can have 28 to 31 days and a year 365 or 366. That is why the calculator offers averages. The Gregorian calendar has 97 leap years every 400 years, so its mean year is 365.2425 days and its mean month 365.2425 ÷ 12 = 30.436875 days. Astronomers use the Julian year of exactly 365.25 days, for example in defining the light-year.

Worked example

Default inputs: 1 hour converted to seconds.

1. 1 hour = 60 minutes, and each minute = 60 seconds.
2. 1 × 3,600 ÷ 1 = 3,600 seconds.
3. Other rows: 3,600,000 ms, 3,600,000,000 µs, 3,600,000,000,000 ns, 60 minutes.
4. Larger units: 1 ÷ 24 = 0.0416666667 days, 1 ÷ 168 = 0.005952381 weeks.
5. 3,600 ÷ 2,629,746 = 0.0013689535 average months; 3,600 ÷ 31,536,000 = 0.0001141553 years (365 d); 3,600 ÷ 31,557,600 = 0.0001140771 Julian years.

How to read the result

Results for seconds, minutes, hours, days and weeks are exact. Results in months or years are averages and can differ from a real calendar period by a day or more. For a specific stretch between two dates (for example, a contract term), count calendar days instead.

Common mistakes

• Treating a month as exactly 30 days or 4 weeks; 4 weeks is only 28 days.
• Forgetting leap years: a leap year has 8,784 hours instead of 8,760.
• Writing decimal hours as minutes: 1.5 hours is 1 hour 30 minutes, not 1 hour 50 minutes.

Frequently asked questions

How many seconds are in a day?

86,400 seconds (24 × 60 × 60).

How many hours are in a year?

8,760 hours in a 365-day year and 8,784 in a leap year.

How many minutes is 0.75 hours?

0.75 × 60 = 45 minutes.

Sources: BIPM, The International System of Units (SI Brochure), 9th edition, 2019 · NIST Special Publication 811 (2008), Guide for the Use of the SI, Appendix B