Date Duration Calculator
To calculate the duration between two dates, enter both dates. TimeSpanCalc shows the elapsed duration and lets you convert it into days, weeks, months, or years.
What a date duration is
A date duration is the quantity of time that has passed — or will pass — between two specific dates. It answers "how much time?" rather than "what date?" and is expressed as a number with a unit: 45 days, 7 weeks, or 2 years and 3 months.
Enter the earlier date in field A and the later date in field B. The calculator returns the elapsed duration instantly. This is sometimes called a date span — the two terms are interchangeable.
Converting a duration between units
Tap the result to cycle between total days, total weeks, and a combined years + months + days breakdown. Each view represents the same duration in a different form.
Days are always exact. Weeks divide the day count evenly with a remainder. The years + months + days view uses calendar-aware months, so it accounts for months of 28, 29, 30, or 31 days rather than assuming a fixed length.
This makes it easy to restate a duration in whichever unit fits your context — days for short spans, weeks for project tracking, and years + months for longer periods like tenancies or contracts.
Common uses for duration tracking
Contract and subscription length — check how long a service agreement or subscription has been running.
Billing periods — verify the exact duration of a billing cycle or calculate pro-rated charges.
How long since or until an event — find the elapsed time since a milestone or the time remaining before a deadline.
Records and claims — document the exact span for insurance claims, warranty periods, or compliance records.
Related calculators
Days between dates — count the exact number of calendar days between any two dates.
Time period calculator — measure the length of a time period in years, months, and days.
Working days calculator — count only Monday-to-Friday business days between two dates.
Days until calculator — count the days remaining until a future event.
Frequently Asked Questions
What is a date duration calculator?
A date duration calculator finds the amount of elapsed time between two dates and lets you view that duration in different units — days, weeks, months, or years.
What is a date span?
A date span is the stretch of time from one date to another, measured as a quantity of elapsed time. It is the same concept as a date duration, just a different term.
How do I convert a duration to weeks or months?
Enter both dates and tap the result to cycle through views: total days, total weeks, and a combined years + months + days breakdown.
Are month and year durations exact?
Yes. TimeSpanCalc uses calendar-aware arithmetic, so "1 month" means the same calendar date in the next month, not a fixed 30-day block. The result is always precise.
How do I find the duration since a past event?
Enter the past event date in field A and today in field B. The result shows the exact elapsed duration from that event to now.