Our Mission
DueDateCalculators.com was created to provide a simple, reliable tool for estimating pregnancy due dates based on standard medical calculation methods. We understand that discovering you’re pregnant brings a mix of excitement and questions — and one of the first questions is always: “When is my baby due?”
Our goal is to offer clear, easy-to-understand information that helps individuals better understand how due dates are typically determined. We believe that knowledge empowers expectant parents to have more informed conversations with their healthcare providers.
We are committed to presenting accurate, research-based explanations of common pregnancy calculations while keeping the experience simple and accessible. Our calculator uses the same formulas that healthcare providers use, presented in a way that anyone can understand and use.
Our Values
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Medical AccuracyWe use medically-recognized calculation methods to provide estimates that align with standard healthcare practices.
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TransparencyWe clearly explain our calculation methods and emphasize that our tool provides estimates, not medical diagnoses.
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AccessibilityOur tool is completely free, requires no sign-up, and is designed to be easy to use for everyone.
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ResponsibilityThis website does not replace professional medical care. We encourage all users to consult a licensed healthcare provider for confirmation of pregnancy details and medical guidance.
Our Calculator Methods
We offer three standard methods for calculating your estimated due date:
- Last Menstrual Period (LMP) — The most common method, based on Naegele’s Rule: adding 280 days (40 weeks) to the first day of your last period.
- Conception Date — If you know when conception occurred, we add 266 days (38 weeks) to that date.
- Ultrasound Dating — Using your ultrasound date and the gestational age shown on the report to calculate backward to your estimated due date.
References
This calculator is based on established medical guidelines from the following trusted sources:
- NHS (National Health Service) — The UK’s national healthcare system provides guidance on calculating pregnancy due dates, typical pregnancy length, and how estimates are determined from the last menstrual period.
- American Pregnancy Association — A pregnancy-focused educational nonprofit that explains common medical methods for estimating due dates, including counting 40 weeks (280 days) from the first day of the last menstrual period.
- Mayo Clinic — Provides clinical guidance used by healthcare professionals for estimating due dates and determining gestational age, including the role of last menstrual period and ultrasound confirmation.