Date Add & Subtract Calculator
Add or subtract calendar days, weeks, months or years, with explicit month-end handling.
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 Add & Subtract 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
Move a date forward or backward by a whole number of calendar units. Days and weeks use UTC date-only arithmetic. Months and years preserve the day where possible, otherwise clamp to the last day of the target month. Month-end clamping is reported and may make a reverse operation non-invertible. This is calendar arithmetic, not a legal deadline or business-day calculator.
Supported files, limits & important details
Input and resulting dates must remain in 1900?2100. Calendar units only; no holiday, working-day or legal deadline adjustments. 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.
Keep your workflow moving
Questions about Date Add & Subtract Calculator
How do I use Date Add & Subtract 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 Add & Subtract Calculator?
No. Date Add & Subtract 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 Add & Subtract Calculator?
Move a date forward or backward by a whole number of calendar units. Days and weeks use UTC date-only arithmetic. Months and years preserve the day where possible, otherwise clamp to the last day of the target month. Month-end clamping is reported and may make a reverse operation non-invertible. This is calendar arithmetic, not a legal deadline or business-day calculator.
Need help choosing a workflow? Read our practical PDF and file guides. How your data is handled.