DIY Cost Tools
Time Converter
CONVERSION CALCULATOR
Convert elapsed time between milliseconds, seconds, minutes, hours, days, weeks, and common 365-day years.
How it works
The calculator converts the source value to seconds and then divides by the number of seconds in the destination unit.
Conversion formula
Converted time = entered time × seconds per source unit ÷ seconds per destination unit.
Worked example
2.5 hours equals 150 minutes.
Important limits
- A common year is treated as exactly 365 days.
- Calendar months are excluded because their lengths vary.
- Leap seconds and daylight-saving transitions do not change a pure duration conversion.
Frequently asked questions
How many seconds are in a day?
A standard 24-hour day contains 86,400 seconds.
Why are months not included?
Calendar months vary from 28 to 31 days, so they do not have one fixed conversion factor.
Understanding time-unit conversions
This converter treats time as a duration. Units such as seconds, minutes, and hours have fixed relationships, but calendar days, months, and years can vary when a specific date range is involved. For scheduling across dates, account for month length, leap years, daylight-saving changes, and local time zones separately.
Keep sufficient decimal precision when converting small fractions of a unit. For example, 0.25 hour equals 15 minutes, while a rounded decimal hour used on a timesheet may produce a slightly different payroll total. When converting project or machine time, verify whether breaks, downtime, or inclusive start and end points should be counted. Use a date-and-time calculator rather than a simple unit conversion when calendar rules affect the answer.
Review notes
Factors use standard SI seconds and conventional 60-second minutes and 24-hour days. Last reviewed September 30, 2026.