Time conversion seems straightforward — 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day — but irregular relationships between larger units (days, weeks, months, years) create confusion. Unlike metric conversions that use consistent powers of 10, time uses base-60 (sexagesimal) for small units and irregular counts for larger ones. A year is not exactly 365 days (it is 365.2422 days, hence leap years). A month ranges from 28 to 31 days. These irregularities make precise time arithmetic harder than it appears, especially when calculating durations across different units for project management, payroll, or scheduling.

When to Use Time Conversions

Project planning — converting deadlines from weeks to working days or hours for task estimation.
Payroll calculations: converting between hourly rates and annual salaries (2,080 work hours per year in the US).
Cooking and science: converting recipe times from minutes to seconds for precision timing.
Travel planning: calculating flight durations, layover times, and jet lag adjustments across time zones.

Common Time Conversion Mistakes

1Assuming every month has 30 days when calculating deadlines. February has 28 (or 29), and four months have only 30 days.
2Forgetting that "a fortnight" (used in the UK and Australia) is exactly 14 days, or 2 weeks.
3Mixing up decimal hours and hours:minutes. 1.5 hours = 1 hour 30 minutes, but 1.75 hours = 1 hour 45 minutes (not 1 hour 75 minutes).
4Using 365 days per year for multi-year calculations. Over 4 years, the ~0.25 day error accumulates to a full day (leap day).

Practical Time Examples

A standard work year: 52 weeks × 40 hours = 2,080 hours. At $25/hour, that equals $52,000/year.

10,000 hours (the "mastery" benchmark): equals about 4.8 years of 40-hour work weeks.

A million seconds ≈ 11.57 days. A billion seconds ≈ 31.7 years.

Most Used Time Converters

Hours → Minutes Minutes → Hours Days → Hours Hours → Days Minutes → Seconds Weeks → Days