Add or Subtract Weeks

Add or subtract whole weeks from a date.

Mathematically exact

Interactive calculator

This calculator becomes interactive when JavaScript is available. The page still provides its method, limits and related tools without JavaScript.

How it works

Enter the requested values, review the input assumptions, and calculate the result. The result uses deterministic calendar or arithmetic rules on the values you enter. Dates are normalized before calculation, and invalid inputs are rejected.

Result classification

Mathematically exact. The result uses deterministic calendar or arithmetic rules on the values you enter. Dates are normalized before calculation, and invalid inputs are rejected.

Limitations

Exact for the stated rule and valid inputs; it does not decide legal, medical, contractual or policy questions.

Frequently asked questions

How does this tool work?

The result uses deterministic calendar or arithmetic rules on the values you enter. Dates are normalized before calculation, and invalid inputs are rejected.

What should I verify?

Exact for the stated rule and valid inputs; it does not decide legal, medical, contractual or policy questions.

Practical guide

How to use the Add or Subtract Weeks

Reviewed 27 July 2026

Enter the known values.Use the date, time, place or duration requested above.
Check the assumptions.Confirm time zone, weekend, inclusion and rounding choices when shown.
Read and reuse the result.Copy, share or continue to a related tool without retyping unnecessary information.

Common uses

The Add or Subtract Weeks is useful for project schedules, contracts, delivery dates and personal planning.

Edge cases to check

Pay particular attention to month ends, leap years, inclusive counting and dates entered in reverse order.