Date and time tools
Calculate days between dates, exact age, Unix timestamps and hour/minute conversions.
Tools in this category
Days Between Dates
Calculates the days between two dates.
Age Calculator
Calculates exact age in years, months and days.
Add Days to a Date
Adds days to a date.
Subtract Days from a Date
Subtracts days from a date.
Time Difference Calculator
Calculates the difference between two times.
Hours to Minutes
Converts hours to minutes.
Minutes to Hours
Converts minutes to hours.
Current Unix Timestamp
Current Unix timestamp and date converter.
Timestamp to Date
Converts a Unix timestamp to a readable date.
Stopwatch
Stopwatch with laps and hundredths.
Timer
Countdown with hours, minutes and seconds.
Pomodoro Timer
Pomodoro technique with configurable phases.
Interval Timer
Configurable work/rest rounds.
Calculating dates looks simple until you have to decide whether a day counts or not, whether "a month" means 30 days or the real calendar month, or whether the result can be negative. This guide separates the operations so you know exactly what each tool calculates.
Date difference, adding/subtracting days and duration
The difference between two dates is always shown as a positive number of days, no matter which one you enter first -- the tool calculates the subtraction and takes the absolute value. The calculation uses midnight in your local time zone (not UTC): it subtracts the two instants and rounds to the nearest whole day, which in practice gives the correct number of calendar days even if a daylight saving change falls between the two dates -- it's a rounding approach that works well for this case, not a universal time zone system. Adding or subtracting days from a date respects the real calendar: whether the month has 30, 31 or 28/29 days, the shift correctly rolls over into the next month or year.
Exact age and time difference
The age calculator doesn't count days and divide by 365: it calculates real calendar years, months and days from your birth date, the same way you'd count it by hand using full months. You can pick the reference date (today by default) to find your exact age at any other point, past or future. The time difference calculator works with times of day (not full dates) and assumes the end time falls within the next 24 hours: if you enter an end time that looks "earlier" than the start, it assumes it crossed midnight and adds a day -- it can't handle differences longer than 24 hours.
Minutes, hours and Unix timestamps
Converting hours to minutes or minutes to hours is a direct unit conversion, decimals included (1.5 hours is 90 minutes). A Unix timestamp counts the seconds elapsed since January 1, 1970 in UTC; the converter shows you both the UTC time and your local time when converting a timestamp to a date, so you don't mix the two up.
Real limits
These tools don't distinguish business days from weekends or holidays: they count natural calendar days. None of them calculates legal, labor or tax deadlines (which often have their own business-day rules, local holidays, or inclusive/exclusive counting specific to that regulation) -- for those cases, verify the exact deadline with the relevant official source.
The dates and times you enter are calculated in your browser, never sent to a server.
Frequently asked questions
Can the days-between-dates result be negative?
You'll never see a negative number: the tool always shows the absolute value, regardless of which date you enter first.
Is a month always counted as 30 days?
Not in the age calculator or when adding/subtracting days: the real calendar is used, so January has 31 days and February has 28 or 29 as appropriate.
Can the time difference calculator handle more than a full day?
No. It only works with times of day (not dates), and if the end time looks "earlier" it assumes it crossed midnight once, adding 24 hours -- it doesn't handle differences spanning several days.
Do these calculators distinguish business days from holidays?
No, they all count natural calendar days. None accounts for weekends, local holidays, or the specific counting rules of legal or labor deadlines.
Why does the Unix timestamp show two different times?
Because a timestamp has no time zone of its own: it represents seconds since 1970 in UTC. The converter shows you that UTC time as well as the one matching your local time zone, so you can pick whichever you need.