About Pregnancy Tools

Pregnancy Tools is a small, independent project building free, calm, no-signup pregnancy calculators — for the moments when you just need a quick answer without navigating an app store, creating an account, or wading through twenty pop-ups.

Why this site exists

Pregnancy is full of questions that have simple, well-defined answers: when am I due, how many weeks am I, when is my fertile window, how long was that contraction. Most existing sites bury these tools under tracking forms, modal pop-ups, and aggressive newsletter prompts. We thought it should be easier than that.

How the calculations work

Our due date calculator uses Naegele's rule (last period + 280 days, adjusted for cycle length), the same method most clinicians start from. The week tracker counts gestational age the standard way, from the first day of your last period rather than from conception. Weight gain ranges come from the 2009 Institute of Medicine guidelines. Growth percentiles use World Health Organization reference values.

We document the maths on each tool page so you can check it, including where a method is an approximation. The growth percentile calculator, for example, uses a normal-distribution approximation rather than the full WHO LMS method, and says so on the page, because being clear about a limitation is more useful than implying a precision we do not have.

Not medical advice

Every calculator on this site is for general information only. Pregnancy is unique to every person, and only your obstetrician, midwife, or pediatrician can give you advice that is right for you. If something feels wrong, call them. Always.

How this site is funded

We run on a small server and are supported by display ads. No tracking beyond what is needed to show those ads and to count page views with a self-hosted, cookie-free analytics tool. No email signups. No premium tier. If the site helps you, the best thing you can do is share it with a friend who is expecting.

Contact

Questions, corrections, or suggestions? Email hello@pregnancytools.net or use the contact page. If you think a calculation is wrong, please do tell us — we will check the maths.