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Vaccination Due Date Calculator

Work out vaccination due date instantly with clear inputs, formula shown and shareable results.

About Vaccination Due Date Calculator

Counts forward from the date of birth to the scheduled age for a vaccine dose and applies the minimum interval before the next dose in the series.

Formula

Schedule arithmetic

Due date = date of birth + scheduled age in weeks; next dose is no earlier than the due date plus the minimum interval

Worked example

With the default values below, Vaccination Due Date Calculator returns Dose due date of April 12, 2026. Change any input above and every figure here is recalculated in your browser.

Inputs used

Date of birth
2026-03-01
Scheduled age for this doseaccepts 0–260 weeks
6 weeks
Minimum interval since the previous doseaccepts 0–52 weeks
4 weeks

Results

Dose due date
April 12, 2026
Earliest acceptable date
April 8, 2026
Earliest date for the following dose
May 10, 2026
Age at the due date
1.38 months

Step by step

  1. 1Values used
  2. 2Schedule arithmetic
  3. 3Dose due date= 2026-04-12
  4. 4Earliest acceptable date= 2026-04-08
  5. 5Earliest date for the following dose= 2026-05-10
  6. 6Age at the due date= 1.38 months

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Can a dose be given slightly early?

Most schedules allow a grace period of about four days, but doses given earlier are usually not counted.

What if the schedule is delayed?

Catch-up schedules keep the minimum intervals rather than restarting the course.

Related Calculators

Vaccination Due Date Calculator – Calculate Dose due date