Disclaimer

Last updated: September 2026. Please read this page carefully before using our calculators.

Educational information only

All content on DueDateCalc — calculators, articles, tables, and examples — is published for general educational purposes. It is not medical advice and is not a substitute for a qualified professional. We are not physician or registered dietitians, and no client or advisory relationship is created by your use of this Site.

Our calculators implement the standard obstetric dating formulas — Naegele's rule, IVF transfer dating — with the same assumptions clinicians use for initial estimates. Ultrasound dating, especially first-trimester, remains the clinical gold standard and commonly shifts these dates.

Nothing here is medical advice or a substitute for prenatal care. Bring questions about dating, milestones, or symptoms to your obstetric provider, who can see the whole picture.

Accuracy of calculations

We implement well-known, publicly documented formulas (see the methodology section on each calculator page and ACOG and NIH public guidance as applicable). Even correctly implemented formulas produce estimates that depend on your inputs and assumptions. Real-world outcomes vary. Do not rely on a single web tool for a consequential decision.

Advertising disclosure

DueDateCalc is funded by display advertising served through Google AdSense. Advertisers have no influence over our content, formulas, or editorial choices, and placement of an ad is not an endorsement.

Errors and corrections

If you spot an error, please email hello@www.duedatecalc.com with the inputs you used. Verified corrections are published promptly.