Chances of Getting Pregnant on the Pill – Calculator & Guide

Use the calculator above to estimate your chance of pregnancy while taking the pill. Choose your pill type, select perfect vs typical use, and (optionally) add a second method. If you recently missed or were late with pills, use the dedicated missed-pill tool linked below for a more precise answer.

Second Method

How to use this for pill users

  1. Select your pill type: combined pill or progestin-only pill (mini-pill).
  2. Choose perfect if it was taken exactly as directed with no lapses; choose typical if there were any slip-ups, late starts, condom issues, or uncertainty.
  3. Optionally add a second method (e.g., condoms) to see how it changes the risk.

Have specific misses or late pills? Get a tailored result with the Missed Pill Pregnancy Risk Calculator.

What changes your chances on the pill

  • Timing and consistency: Taking pills at the same time each day matters—especially for the mini-pill.
  • Missed/late pills: Multiple misses or a late restart after the hormone-free break raises risk (use the missed-pill tool above).
  • Vomiting/diarrhea: Within a few hours of a dose can prevent absorption.
  • Certain medicines/supplements: Rifampin-like antibiotics, some seizure meds, and St. John’s wort can reduce effectiveness. Check with a clinician or pharmacist if unsure.
  • Backup and stacking: Adding condoms reduces risk further and protects against STIs.

Annual failure rates are very low with perfect use (around 1 in 300) and higher with typical use (several in 100). Your per-act chance varies by cycle timing and the factors above—this is what the calculator estimates.

If you had a slip-up

If you missed pills, started a new pack late, or had vomiting/diarrhea close to a dose, consider emergency contraception (EC). Compare timing and options with the Morning-After Pill Effectiveness Calculator, then follow the instructions on when to resume/continue your pill and whether to use backup.

When to take a pregnancy test

Most people get a reliable result from the first missed period. To see accuracy by day, use the Pregnancy Test Accuracy Calculator.

Important

This page estimates risk using published effectiveness data and your inputs. It does not diagnose or replace care from a clinician.