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Health & Fitness

Pregnancy Week Calculator

Find how many weeks and days pregnant you are on a given date, the trimester and days until the due date.

Your inputs

Use the Today button for the current date.

Results

Gestational age

10 weeks 3 days

Trimester
First trimester
Days until due date
207
Due date
Thursday, October 8, 2026

≈Estimate based on the stated model and assumptions

Notes for this result

  • Gestational age is counted from the first day of the last period, about two weeks before conception. Confirm dating with your healthcare provider.

Inputs are never added to links for financial, salary or health calculators.

What this calculator does

Gestational age is counted from the first day of the last menstrual period, about two weeks before conception.

Formula and method

Gestational age = date − LMP (or due date − 280 days); trimesters: up to week 13, weeks 13–26, week 27 onward

Worked example

Calculated by this tool with its default inputs:

Inputs

  • I know my: Last menstrual period (first day)
  • Date: 2026-01-01
  • Calculate for date: 2026-03-15

Results

  • Gestational age: 10 weeks 3 days
  • Trimester: First trimester
  • Days until due date: 207
  • Due date: Thursday, October 8, 2026

How to read the results

Your clinician may adjust dates after an ultrasound.

Assumptions and limitations

  • This does not replace prenatal care.

Health results are general estimates for adults and do not replace medical advice, diagnosis or treatment. Speak to a qualified health professional about your personal situation, especially during pregnancy or if you have a medical condition.

Questions

Why am I “2 weeks pregnant” at conception?

Because the count starts from the last period, not from conception.

Methodology and verification

Result type
Estimate based on the stated model and assumptions
Formula version
1.0
Automated verification
3 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

Privacy

Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Because this calculator can involve personal financial or health details, your inputs are never added to share links or saved to history. Privacy policy