Know your body's
timing
Fertility and pregnancy calculators that run entirely in your browser. Nothing you enter is uploaded or shared.
Five tools, no fluff
Each answers one question properly, and says where the estimate stops being reliable.
Ovulation Calculator
Your fertile window, ovulation day, and the best three days.
OpenDue Date Calculator
Due date from your last period, conception date or IVF transfer.
OpenBaby Size by Week
Your baby's size and development, week 4 to 40.
OpenPeriod Tracker
Your real average cycle, and your next twelve period dates.
OpenHair Fall Test
Stage it on the clinical scale, then test for the cause. Men and women.
OpenSafe Sex Days
Higher and lower fertility days - with the real failure rates.
OpenWhy these are different
Genuinely private
No account, no server, no analytics on what you type. Your dates never leave your browser.
Shows the reasoning
Every tool shows how it reached the number, and where the estimate weakens.
Readable by everyone
Colour is never the only signal. Every chart carries labels and a data table.
Not contraception, and not medical advice. These are estimates from cycle averages - a dating scan beats any calendar. Always consult a doctor about your own situation.