Calculate gestational age and estimate due date based on last menstrual period.
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Enter Your Measurements
Results
Days Until Due Date
90
days
Gestational Weeks
27
weeks
Additional Days
2
days
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Formula
Gestational Age = Days since LMP / 7; Due Date = LMP + 280 days
How to Use This Calculator
How to Use
- 1
Enter the first day of your last menstrual period (LMP).
- 2
Get your current gestational age and due date.
Frequently Asked Questions
Frequently Asked Questions
What is gestational age?
Gestational age is calculated from the first day of the last menstrual period (LMP), not from conception.
How accurate is the due date?
Due dates are estimates. Only 5% of babies arrive on the due date. 90% arrive within 2 weeks of the due date.
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About This Calculator
This calculator uses the formula: Gestational Age = Days since LMP / 7; Due Date = LMP + 280 days. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.
Built and maintained by the CalcSmart team. Last updated March 2026.
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<iframe src="https://calcsmart.io/embed/pregnancy-week-calculator" width="100%" height="520" frameborder="0" style="border-radius:8px;border:1px solid #e5e7eb" title="Pregnancy Week Calculator"></iframe>Free to embed. Attribution link included automatically.