Calculator library

Fertility and Pregnancy Calculators

Free browser-based tools for cycle education, fertility timing, due date estimates, and planning conversations with a healthcare professional.

Period Calculator

Estimate your next period, current cycle day, fertile window, and future period dates.

DPO Calculator

Count days past ovulation and compare implantation and pregnancy test timing.

Implantation Calculator

Review a possible implantation window and estimated testing dates.

Pregnancy Test Calculator

Compare earliest, more reliable, and later home pregnancy test dates.

Luteal Phase Calculator

Estimate luteal phase length from ovulation to the next period start.

Ovulation Calculator

Estimate your ovulation date, fertile window, next period, and possible due date from your last period and average cycle length.

Irregular Period Calculator

Use several recent period dates to estimate an average cycle length and a likely fertile window when cycles vary.

Due Date Calculator

Estimate a pregnancy due date from the first day of the last menstrual period or a likely conception date.

How to Choose the Right Calculator

If your cycles are fairly predictable, the standard ovulation calculator is usually the simplest place to start. If your period dates vary from month to month, the irregular period calculator may provide a more cautious estimate because it uses more than one recent cycle.

If you already have a positive pregnancy test or are planning prenatal timing, the due date calculator can help estimate gestational age and delivery timing. If you know an ovulation date, the DPO and implantation tools use that date directly and avoid adding a cycle-length assumption.

All Ovucal calculators are educational estimates. They do not diagnose pregnancy, confirm ovulation, replace contraception counseling, or substitute for medical care.

Tips for Better Inputs

  • Use the first full day of menstrual bleeding as the first day of your period.
  • Compare several months of cycle data when possible.
  • Use ovulation predictor kits or body signs if you need more confidence around timing.
  • Contact a clinician for severe symptoms, repeated missed periods, infertility concerns, or pregnancy questions.

Last updated: August 19, 2026. Reviewed for clarity by the Ovucal Editorial Team.