Pregnancy & Menstrual Cycle Calculators
Date-based calculators for pregnancy and the menstrual cycle. They give estimates from the dates you enter, and the results are never a substitute for dating scans or advice from a midwife or doctor.
- Due Date CalculatorEstimate your due date from the first day of your last period, a conception date, an IVF transfer or a dating scan, and see weeks, trimester and key dates.
- Ovulation CalculatorEnter the first day of your last period and your cycle length to see your estimated ovulation date, fertile window and the next few cycles.
How these calculators work
Every calculator in this group names its formula, shows a worked example and lists the sources behind its categories. The numbers are estimates based on the details you enter, so they work best as a starting point for a conversation with a doctor, dietitian or trainer rather than as a final answer.
Results are for information only and are not medical advice. See our editorial policy and methodology for how we choose and review formulas.