Dates & Time calculators, in short
Date math breaks at month ends and leap years, so these calculators count in calendar units rather than dividing days by 365. Both also give plain day totals for deadlines and billing.
Popular tools in this category
What can you calculate here?
- An exact age in years, months, and days, plus the next birthday
- Days, weeks, months, and years between two dates
- A business-day count that excludes weekends and the holidays you list
Every dates & time calculator
Each tool below shows the formula it uses, a worked example, and what the result means in practice.
Common questions about dates & time calculations
- Why not just divide days by 365?
- Because leap years and uneven month lengths make that drift. These calculators count in calendar units — whole years, then months, then days — and also give you the plain day total.
- Is the end date counted?
- The date difference is measured between the two dates, so the start day is not double counted. Business-day counts exclude weekends and any holidays you list.
- Do these tools use my time zone?
- Dates are handled as plain calendar dates, so the result does not shift with time zone or daylight saving changes.