Free cycle tools
Three simple calculators to find your way around your cycle: when your next period is due, when you probably ovulate, and which phase you are in today. Everything is calculated in your browser: nothing is sent or stored.
Ovulation & fertile window calculator
Estimate your ovulation day and fertile window, with a 3-cycle calendar.
Next period calculator
Predict your next 6 periods from the start of your last one.
Which phase of my cycle am I in?
Find today’s cycle phase and what it often means for energy and mood.
All three tools use the same rules as the Luteal app: the luteal phase (after ovulation) lasts about 14 days on average, so ovulation happens roughly 14 days before your next period, and the fertile window covers the 5 days before ovulation, the day itself and the day after.
They are guides, not certainties: each page explains the method, its limits, and when it is better to talk to a health professional.