Time Unit Converter Guide

Key points

• ▸ Exact ratios: 1 min = 60 s. 1 hr = 60 min = 3,600 s. 1 day = 24 hr = 1,440 min = 86,400 s. 1 week = 7 days = 604,800 s.
• ▸ Average month: 30.4375 days (365.25 / 12). The converter uses this for durations — do NOT use it to add "one month" to a specific date.
• ▸ Average year: 365.25 days (Julian). Actual calendar years alternate between 365 and 366 (leap years, every 4 years with the 100/400 exception).
• ▸ A "month" and a "year" in the converter are statistical averages; real calendar math needs a date-difference calculator.
• ▸ Typical confusion: "30 days" ≠ "1 month" for precise dating. 30 days after Jan 1 is Jan 31; one month after Jan 1 is Feb 1. The converter will not tell you which you need.
• ▸ Useful memorised durations: 1 billion seconds ≈ 31.7 years. 1 million seconds ≈ 11.6 days. 1 year ≈ 3.1536 × 10⁷ s.

How to

1. Enter a duration value.
2. Pick source and target units.
3. If the source or target is "month" or "year," the converter uses average values (30.4375 days / 365.25 days).
4. For specific calendar dates — "how many days until my deadline" — switch to the date-difference calculator.
5. For wall-clock timing or shift work, use the hours calculator.

Examples

• 1 day in seconds
  24 × 60 × 60 = 86,400 s. The number every developer forgets to use exactly.
• 3 years in days (statistical)
  3 × 365.25 = 1,095.75 days. For a specific 3-year span, use actual calendar dates.
• 10,000 hours to years
  10,000 / (24 × 365.25) = 1.14 years. Popularised as the mastery threshold — roughly 3.5 years at 8 hr/day.

When to use which tool

• Time Converter
  Durations, timers, estimating total hours in a year, physics homework, pace calculations.
  Convert between seconds, minutes, hours, days, weeks, months, and years.