Pregnancy Chance Calculator

Last updated Sep 9, 2026 | By

Get an instant estimate of your chance of pregnancy, based on published research and the details you enter.

Count each separate occasion of vaginal intercourse you want to include. Enter a whole number. Leaving this blank uses 1.
Enter the age in whole years of the person who could become pregnant. Leaving this blank uses age 30.
Choose Typical use if there may have been mistakes. Choose Perfect use only if you followed all instructions every time. If unsure, leave Typical use selected. Learn more.
Second method
Choose Typical use if there may have been mistakes with this second method. Choose Perfect use only if you followed all instructions every time. If unsure, leave Typical use selected.
Enter the male partner’s age in whole years. Leaving this blank uses age 25.
Enter your height in feet and inches, or choose cm for centimeters. For 5 ft 5 in, enter 5 and 5 in the separate boxes. Leaving height blank uses 5 ft 5 in (165.1 cm).
Choose lbs for pounds or kg for kilograms, then enter your weight. Leaving this blank uses 150 lb (about 68 kg).
Enter your total working hours in a usual week, including all jobs. Enter 0 if you do not work; leaving this blank also uses 0.
Enter how many cigarettes you smoke in a usual day. Count individual cigarettes, not packs. Enter 0 if you do not smoke; leaving this blank also uses 0.
Enter your total number of alcoholic drinks in a usual week, not the number of days you drink. Enter 0 if none; leaving this blank also uses 0.
Choose Yes if you are trying to become pregnant, or No if you are not. You can leave both unselected if you prefer.
Peer-Reviewed Science
Updated Sep 2026
See Methodology
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How to Use Our Calculator

  1. Enter the number of intercourse events you want to estimate for (any time frame).
    Only one event? Try the One-Time Calculator.
  2. Enter your age (optional).
  3. Choose a contraceptive method (optional) - leave as “No contraceptive” if none was used.
  4. For a more accurate result, use the 'Advanced Settings' inputs. The more you use, the more precise our estimate will be.
  5. Press Calculate

We don’t store your inputs. Results are estimates and show a capped range (never exactly 0% or 100%).

A screenshot of the Simple Pregnancy Chance Calculator, showing input fields for contraceptive method and intercourse frequency.

How Our Calculators Work: The Science Behind Your Estimate

This calculator combines published data on contraceptive effectiveness, fertile-window timing, age, and lifestyle associations with the details you enter to provide a planning estimate. The sources explain the background evidence used for this planning estimate. Individual outcomes can vary.

The result is a statistical estimate. It cannot account for every fertility factor or predict what will happen for one person.

The Key Factors in Our Algorithm

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Female Age

A primary driver of fertility. Our model accounts for the natural decline in egg quantity and quality over time, based on guidelines from the American College of Obstetricians and Gynecologists (ACOG).

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Male Age

Male age is included as a broad factor. A systematic review and meta-analysis found age-related declines in several semen measures, although this does not predict an individual partner’s fertility.

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Intercourse Timing

We account for intercourse timing and frequency. ASRM guidance says intercourse every 1 to 2 days during the fertile window gives the highest pregnancy rates, while 2 to 3 times per week is nearly equivalent.

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Body Mass Index (BMI)

BMI is used as a broad contextual factor. In one observational study, BMI above the studied threshold was associated with longer time to pregnancy. The calculator uses this information as part of the overall planning estimate.

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Lifestyle Factors

Smoking and alcohol are treated as broad contextual factors. An observational study found longer time to pregnancy at the smoking and partner-alcohol levels it examined.

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Contraceptive Use

We use large-scale study data, including the landmark Trussell (2011) study on contraceptive failure, to factor in typical and perfect-use rates.

Estimated Pregnancy Chance vs. Cigarette Intake chart.
An example of how the calculator applies its simplified smoking adjustment. This is a planning estimate, not an individual prediction.

Foundational Data Sources & Primary Research

For more of the published background sources used across the site, visit our Research Library.

Frequently asked questions

How many days after my period will I conceive?
If your cycle is ~28 days, the fertile window is usually cycle days 10–15, with ovulation around day 14. If your cycles are shorter or longer, the window shifts. You can get pregnant soon after a period if you ovulate early. For a personalized window, try the Ovulation Calculator.
When is the 100% chance of getting pregnant?
There’s no time with a 100% chance. The highest odds are the 2–3 days before ovulation and ovulation day itself. After 12–24 hours post-ovulation, the chance for that cycle drops sharply. Use the Ovulation Calculator to see your most fertile days.
How can I be sure I ovulated?
Confirmation is retrospective: a sustained basal body temperature rise after ovulation, or ultrasound. OPKs show an LH surge but don’t prove ovulation by themselves. For help interpreting your data, see the BBT Ovulation Calculator and OPK→Ovulation Timing Calculator.
How reliable is the withdrawal method?
Typical-use effectiveness is about 78% over a year (roughly 22 pregnancies per 100 users). Effectiveness depends on perfect timing and consistency. Get a situation-specific estimate with the Withdrawal Risk Calculator or the broader Contraceptive Risk Calculator.
How long can sperm live in the body?
In fertile cervical mucus, sperm can survive up to 5 days, which is why intercourse several days before ovulation can still lead to pregnancy. Outside the body, sperm die quickly. To see how timing affects your odds, try the Ovulation Calculator or the One-Time Pregnancy Calculator.
Can I use this if my cycles are irregular?
Yes - this calculator doesn’t require cycle dates. For a cycle-aware fertile window, try the Ovulation Calculator.
Does breastfeeding change my chances?
It can if you meet strict LAM criteria. Check today’s status with the LAM Eligibility and Risk Calculator or explore timing with the Postpartum Ovulation Calculator.

Medical disclaimer

The information and calculators on this site are educational tools only. They provide statistical estimates based on published research and the details you enter.

They cannot diagnose, predict what will happen for you, or replace personalized advice from a licensed health care professional who knows your full history. Always talk with your doctor, midwife, or other qualified clinician before making decisions about your health, fertility, or pregnancy.

Never ignore, avoid, or delay seeking professional medical advice because of something you read here or a result you see in a calculator. If you think you may be having a medical emergency, call 911 in the United States or your local emergency number.