Pregnancy Chance Calculator

Last updated Feb 14, 2026 | By

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

Count any events you want to estimate for, regardless of time period.
Used to estimate baseline fertility and age-related risks. If blank, this uses 30.
Typical use is average real-world use. Perfect use means correct use every time. Learn more.
Second method
If you select perfect use here, the model assumes correct use every time for this second method.
Used as a fertility modifier. If blank, this uses 25.
If blank, the model uses an average height. Height and weight are used to estimate BMI.
If blank, the model uses an average weight.
Used as a small fertility modifier. If blank, this uses 0.
Used as a fertility modifier. If blank, this uses 0.
Used as a fertility modifier. If blank, this uses 0.
Peer-Reviewed Science
Updated Feb 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) and .
  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 simplified PCC assumptions. The sources explain the background evidence; they do not validate every adjustment as an exact personal prediction.

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

👩

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).

👨

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.

📅

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.

⚖️

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’s exact adjustment is a simplified PCC assumption.

❤️

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; it does not validate the calculator’s exact adjustments.

🛡️

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.