Date Difference Calculator
Pick any two dates — two historical events, a birth and a death, a landing and today — and get the exact gap between them in years, months and days, plus the total in days, weeks and hours.
Frequently asked questions
How is the difference calculated?
Whole years first, then whole months, then the remaining days — the same calendar arithmetic used for ages. The total in days is counted day by day, so leap years (including the century rule: 1900 was not a leap year, 2000 was) are handled exactly.
Does it matter which date I enter first?
Yes. Pick either order — the calculator works out which date is earlier and says so in the result, so you never get a negative answer by mistake.
Where do the preset dates come from?
The presets use widely documented dates: Einstein was born 14 March 1879 and died 18 April 1955; the first Moon landing was 20 July 1969; the Second World War in Europe ran from 1 September 1939 to 8 May 1945. You can change either date after choosing a preset.
Can I compare dates hundreds of years apart?
Yes — the calculation is exact for any dates your browser's date picker accepts, including dates centuries apart. Very old dates use the proleptic Gregorian calendar (the calendar extended backwards), which is the standard convention for date arithmetic.
Is anything I enter stored or sent anywhere?
No. What you type stays in your browser and is not sent to us; loading the page itself contacts our host, as explained in the Privacy Policy.
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