Time Unit Converter
Our free time converter handles time unit conversions. See tables, ratios, and examples for quick reference. Get results you can export or share.
Formula
Result = Value x (FromUnit_seconds / ToUnit_seconds)
Each time unit has a fixed relationship to seconds (the SI base unit). To convert, multiply the input by the source unit's seconds-per-unit factor, then divide by the target unit's factor. This two-step process works for any pair of time units.
Worked Examples
Example 1: Days to Seconds
Problem: How many seconds are in 3.5 days?
Solution: Convert days to seconds using the factor 86,400 seconds/day:\n3.5 days x 86,400 s/day = 302,400 seconds\nOr step by step: 3.5 x 24 = 84 hours, 84 x 60 = 5,040 minutes, 5,040 x 60 = 302,400 seconds.
Result: 3.5 days = 302,400 seconds
Example 2: Weeks to Hours
Problem: Convert 2.5 weeks to hours.
Solution: Convert weeks to hours: 1 week = 7 days x 24 hours = 168 hours\n2.5 weeks x 168 hours/week = 420 hours\nAlternatively: 2.5 x 7 = 17.5 days, 17.5 x 24 = 420 hours.
Result: 2.5 weeks = 420 hours
Frequently Asked Questions
How do time unit conversions work?
All time unit conversions use the second as the base unit, since it is the SI (International System of Units) standard for time. To convert between any two time units, first convert the input value to seconds by multiplying by the appropriate factor, then divide by the target unit's factor. For example, to convert 2 hours to minutes: 2 hours times 3600 seconds/hour = 7200 seconds, divided by 60 seconds/minute = 120 minutes.
What are the most common time conversion factors?
The essential conversion factors are: 1 minute = 60 seconds, 1 hour = 60 minutes = 3,600 seconds, 1 day = 24 hours = 86,400 seconds, 1 week = 7 days = 604,800 seconds, 1 year (average) = 365.25 days = 31,557,600 seconds. For smaller units: 1 second = 1,000 milliseconds = 1,000,000 microseconds = 1,000,000,000 nanoseconds. Memorizing the key factors (60, 24, 7, 365.25) allows you to chain conversions quickly.
How do I convert between very large and very small time units?
For extreme conversions like centuries to milliseconds, use the chain multiplication method. Start from the known factor for each step: 1 century = 100 years = 36,525 days = 876,600 hours = 52,596,000 minutes = 3,155,760,000 seconds = 3,155,760,000,000 milliseconds. Working step by step avoids errors. Alternatively, convert to seconds first (the base unit), then to your target unit in a single division.
How do significant figures affect unit conversions?
Your converted result should have the same number of significant figures as your original measurement. If you measure 5.2 inches (2 significant figures), converting to centimeters gives 13 cm, not 13.208 cm. Using excessive decimal places implies false precision.
What are the most common unit conversion mistakes?
Common errors include confusing fluid ounces with weight ounces, mixing up miles and nautical miles, forgetting that UK and US gallons differ (UK is 20% larger), using the wrong temperature formula, and not accounting for the difference between troy and avoirdupois ounces.
Why do some countries use different unit systems?
Most countries adopted the metric system after the French Revolution standardized it in the 1790s. The US, Liberia, and Myanmar still primarily use imperial/customary units due to historical inertia, though US science and military use metric.