Free tools for your cycle.
Calculators that answer the question and get out of your way. No sign-up. No data collection. No catch.
Period Calculator
Enter your last period and cycle length. Get the dates your next few periods are likely to land on.
Ovulation Calculator
Estimate your fertile window and ovulation day based on your cycle. Whether you're trying or avoiding.
More resources coming soon
We're building more free resources for your cycle. Check back soon.
Why these are free
Every calculator here runs in your browser. Nothing you type gets sent to a server, logged, or sold. Same principle as the app: your body, your data.
These are quick answers, not medical advice. A calculator can estimate your next period or fertile window — it can't diagnose anything. For that, see a professional.
Want tracking that remembers for you and predicts on its own? That's what Bleed is for.
Tools are handy. The app is better.
Bleed tracks your cycle and predicts your next period — all on your phone.
iOS only. Your data never leaves your phone.