Date Difference Calculator
Count calendar days and complete weeks between dates, with an explicit end-date option.
Calculate with your own values
Local processing. No account, uploads or saved history.
Your result
Formula & assumptions
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How to use Date Difference Calculator
- Enter your values and select the applicable mode or units; Load example shows a complete sample.
- Select Calculate, then review the result, formula and counting assumptions.
- Copy the result or download its CSV. Changing an input clears the previous result.
What this tool does
Counts date-only UTC calendar days from the start date to the end date. By default the start is included and end excluded; choosing an inclusive end adds one day. Complete weeks and remaining days are duration units, not calendar months. Leap days are included.
Supported files, limits & important details
End must be on or after start. Dates must be valid calendar dates from 1900 through 2100. Does not calculate age or elapsed clock hours. Browser-local processing; no inputs are uploaded or saved. Numeric inputs are limited to an absolute value of 1 trillion. Results are estimates using JavaScript floating-point arithmetic, not certified financial or engineering calculations.
Input limits are enforced before processing. Clear removes your input and result from this page. This tool does not store your input between visits.
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Questions about Date Difference Calculator
How do I use Date Difference Calculator?
Enter your values and select the applicable mode or units; Load example shows a complete sample. Select Calculate, then review the result, formula and counting assumptions. Copy the result or download its CSV. Changing an input clears the previous result.
Are files or text uploaded when I use Date Difference Calculator?
No. Date Difference Calculator processes your input in your browser. The tool does not upload your document or text for processing. Keep your original and review the result.
What should I check before relying on Date Difference Calculator?
Counts date-only UTC calendar days from the start date to the end date. By default the start is included and end excluded; choosing an inclusive end adds one day. Complete weeks and remaining days are duration units, not calendar months. Leap days are included.
Need help choosing a workflow? Read our practical PDF and file guides. How your data is handled.