Free tools

Calculators

Eleven practical tools for cycle, fertility, and pregnancy planning — grounded in cycle science, free to use, no sign-up required.

Cycle tracking

Understand your pattern from cycles you've already had.

Menstrual cycle / Period calculator

Predict your next period and see your likely fertile window.

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Cycle length calculator

Work out your average cycle length and variability from past periods.

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Fertility & ovulation

Estimate your fertile days and ovulation timing.

Ovulation calculator

Estimate your most fertile days, with a visual cycle timeline.

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Fertility window calculator

See fertile days based on an ovulation estimate.

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Implantation calculator

Estimate the likely implantation window after ovulation.

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Pregnancy & due dates

Estimate due dates and track pregnancy progress.

Pregnancy due date calculator

Estimate due date from your last period, with a progress ring.

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IVF due date calculator

Calculate due date from embryo transfer date and embryo age.

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Due date by ultrasound

Estimate due date from ultrasound measurements.

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Pregnancy weeks → months

Convert gestational weeks to months and see your trimester.

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Early pregnancy testing

Interpret test timing and lab results.

Pregnancy test calculator

Guidance on when a test is likely to detect pregnancy.

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Beta hCG doubling time

Calculate hCG doubling time from two lab results, with a chart.

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