About DueDateCalc
DueDateCalc is the pregnancy calendar: when the due date lands, where you are right now in weeks, and what milestone arrives next — calculated the way clinicians do it.
DueDateCalc exists because pregnancy dating is genuinely standardized (Naegele's rule, 280 days, trimester boundaries) and yet every due-date answer online rounds differently. The clinical math, shown plainly, is what this site does.
Every calculator on DueDateCalc shows its formula and its assumptions on the page, so you can check the math, reproduce it in a spreadsheet, or argue with it. Inputs are processed entirely in your browser — nothing is sent to a server, and there are no accounts.
DueDateCalc is an independent, ad-supported project. We are not affiliated with any lender, brand, agency, or the sources we cite (ACOG and NIH public guidance). If a number looks wrong, the contact page reaches a human who fixes it.
What makes DueDateCalc different
- Your numbers never leave your browser. Every calculator on DueDateCalc runs entirely on your device. We never see, store, or transmit the figures you enter — there are no accounts and no server-side processing of your inputs.
- Published methodology. Each calculator page explains the exact formula it uses and the assumptions behind it, so you can check our work or reproduce it in a spreadsheet.
- Free, forever, without a paywall. DueDateCalc is supported by advertising. There is no premium tier, no email gate, and no upsell.
Independence
DueDateCalc is an independent educational project. We are not affiliated with, endorsed by, or acting on behalf of any government agency, lender, insurer, or the organizations whose formulas and public data we reference (such as ACOG and NIH public guidance). All trademarks and referenced standards belong to their respective owners.
Questions, corrections, or suggestions are genuinely welcome — get in touch.