Breast Cancer Risk Calculator · Gail Model 5-Year & Lifetime Risk

Breast Cancer Risk Calculator

Estimate 5-year and lifetime invasive breast cancer risk using the Gail model (2018 version)

Quick preset

About you

Current age

years

Race / ethnicity

Reproductive history

Age at first menstrual period

Age at first live birth

Breast biopsy history

Number of prior breast biopsies

Atypical hyperplasia found

Atypical hyperplasia means the biopsy showed abnormal but non-cancerous cells (ADH or ALH). If you have never had a biopsy, leave both fields at their defaults.

Family history

First-degree relatives with breast cancer

First-degree relatives are your mother, sisters, and daughters. Do not count aunts, grandmothers, or cousins here.

Quick examples

Risk Assessment Result

5-year risk

— %

— lifetime — average —

5-year risk

— %

Lifetime risk

— %

Relative risk

—

Risk category

—

5-year risk interpretation

5-year risk	Category	Clinical implication

Your risk factor summary

Factor	Your value	Risk contribution

Clinical notes

Threshold for increased risk: A 5-year Gail risk of ≥ 1.67% or a lifetime risk of ≥ 20% is generally considered increased risk. Women in this category may benefit from enhanced screening (e.g., annual MRI in addition to mammography) and discussion of chemoprevention with a healthcare provider.

Model limitations: The Gail model is not appropriate for women with a personal history of breast cancer, DCIS, LCIS, chest radiation for Hodgkin lymphoma, or a known BRCA1/BRCA2 mutation. It also does not include breast density, alcohol use, or other lifestyle factors. The model tends to overestimate risk in younger women and has only modest discriminatory power for individuals.

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Breast Cancer Risk Calculator: Gail Model 5-Year & Lifetime Risk

This Gail model calculator estimates your 5-year and lifetime risk of invasive breast cancer using seven inputs: current age, race, age at first period, age at first live birth, number of prior breast biopsies, presence of atypical hyperplasia, and first-degree relatives with breast cancer. Results show your absolute risk as a percentage, a relative risk multiplier, and a category from low to very high. Everything runs in your browser. No data leaves your device. Fill in the fields, hit Calculate, and you’ll have a number you can bring to your next doctor’s visit.

Breast cancer risk assessment used to live in oncology clinics. Now it sits in a browser tab. The Gail model, formally the Breast Cancer Risk Assessment Tool (BCRAT), was built by the National Cancer Institute to give women a concrete number instead of a vague “family history” concern. A 52-year-old with one affected sister and a prior biopsy gets a very different number than a 52-year-old with none of those factors. That difference matters because a 5-year risk at or above 1.67% opens the door to enhanced screening and risk-reduction conversations. This calculator handles the arithmetic. You still need a clinician to interpret the result. The math follows the 2018 version of the Gail model, including race-specific baseline adjustments.

How to Use This Breast Cancer Risk Calculator

Pick a preset or start from scratch. The preset dropdown loads common profiles like “one affected relative” or “atypical hyperplasia on biopsy.” Choose “Custom / manual input” to enter your own values.
Enter your current age. The calculator accepts ages 20 through 90. Values outside that range get clamped to the nearest limit.
Select your race or ethnicity. Options include White (non-Hispanic), African-American, Hispanic US-born, Hispanic foreign-born, Asian-American, and Native American. The model applies different baseline incidence rates for each group.
Choose your age at first menstrual period. The options are 7–11, 12–13, 14 or older, or Unknown. Early menarche raises the relative risk.
Indicate your age at first live birth. Ranges run from under 20 to 30-plus, plus a “never had a live birth” option. Earlier first birth is protective.
Enter your biopsy history. Select zero, one, or two-plus prior breast biopsies. Then indicate whether atypical hyperplasia was found.
Count your first-degree relatives with breast cancer. Mother, sisters, and daughters only. Zero, one, or two-plus.
Read your results. The hero number shows your 5-year risk. Below it you’ll find lifetime risk, relative risk, and your risk category.

How the Gail Model Formula Works

The calculator produces two numbers from the same core equation: a 5-year absolute risk and a lifetime absolute risk. The math multiplies a baseline risk (from age and race) by a relative risk score built from your reproductive and biopsy history.

Formula: 5-year risk = Baseline 5-year risk (age, race) × Relative risk (menarche, first birth, biopsies, atypical hyperplasia, relatives)

The relative risk component uses coded values. For example, menarche at 7–11 gets a code of 2, while 14 or older gets 0. First live birth under 20 codes as 0; 30 or older codes as 3. Each biopsy adds 0.35 to the log-relative-risk, and each first-degree relative adds 0.55. Atypical hyperplasia contributes a fixed 0.5988 when present. Race-specific recoding applies for African-American, Hispanic, and Asian-American groups. The model caps relative risk between 0.5 and 20, and caps 5-year risk at 60% and lifetime risk at 90%.

If you leave a field as “Unknown,” the calculator treats it as the lowest-risk or neutral value. That’s the model’s default behavior, not a judgment call.

Worked Example: 58-Year-Old with One Affected Sister

A 58-year-old White woman wants to know her 5-year risk. She started her period at 13, had her first child at 27, has had one breast biopsy with no atypical hyperplasia, and her mother had breast cancer.

Step 1: Baseline. For a 58-year-old White woman, the baseline 5-year risk is approximately 0.50%.

Step 2: Relative risk components.

Menarche at 12–13: code 1 → logRR contribution 0.08
First birth at 25–29: code 2 → logRR contribution 0.20
One biopsy: code 1 → logRR contribution 0.35
No atypical hyperplasia: −0.0726
One first-degree relative: code 1 → logRR contribution 0.55

Step 3: Combine. Total logRR = 0.08 + 0.20 + 0.35 − 0.0726 + 0.55 = 1.1074. Relative risk = e^1.1074 ≈ 3.02. The age adjustment for age ≥ 50 adds 0.10 × 1 biopsy = 0.10, pushing RR to roughly 3.34.

Step 4: Multiply. 5-year risk = 0.50% × 3.34 ≈ 1.67%. That lands exactly at the threshold for “increased risk.” Her lifetime risk comes out around 31%. The takeaway: one first-degree relative plus one biopsy pushes an otherwise average profile right to the intervention line.

Frequently Asked Questions

What is a good Gail model score?

There’s no “good” score, only risk categories. A 5-year risk below 1.0% is low. Between 1.0% and 1.66% is average. At or above 1.67% is increased risk. That threshold is the one that matters clinically because it opens access to enhanced screening and chemoprevention discussions.

What does a 5-year risk of 1.67% mean?

It means your estimated probability of developing invasive breast cancer in the next five years is 1.67%. That’s the cutoff the FDA and National Cancer Institute use to define “increased risk.” About one in 60 women in that category would develop breast cancer within five years.

How do I calculate my Gail model breast cancer risk?

Enter seven values into this calculator: age, race, age at first period, age at first live birth, number of breast biopsies, atypical hyperplasia status, and first-degree relatives with breast cancer. The tool multiplies a baseline risk by a relative risk score built from those inputs.

What lifetime risk is considered high for breast cancer?

A lifetime risk of 20% or higher is generally considered increased risk. That’s separate from the 1.67% 5-year threshold. Some women cross one but not the other. Your clinician will look at both numbers together.

Does atypical hyperplasia increase breast cancer risk?

Yes, substantially. Atypical hyperplasia on biopsy roughly quadruples breast cancer risk compared to women with non-proliferative biopsy findings. In the Gail model, it adds a fixed 0.5988 to the log-relative-risk calculation on top of the biopsy count adjustment.

How much does one first-degree relative raise your risk?

Having one first-degree relative with breast cancer roughly doubles your risk compared to someone with no family history. In the Gail model, each first-degree relative adds 0.55 to the log-relative-risk, which translates to a multiplier of about 1.73× for one relative.

Can I use this calculator if I have BRCA1 or BRCA2?

No. The Gail model isn’t designed for BRCA1 or BRCA2 mutation carriers. If you know you carry one of those mutations, your risk is substantially higher than what this model will show, and you need a different assessment approach with a genetics specialist.

What age should I start using a breast cancer risk calculator?

The Gail model accepts ages 20 through 90. In practice, risk assessment becomes more relevant in your 40s and 50s, when baseline risk rises enough that risk factors start to matter. There’s no harm in running it earlier, but the numbers will be small.

Does the Gail model work for all races and ethnicities?

It includes race-specific baselines for White, African-American, Hispanic US-born, Hispanic foreign-born, Asian-American, and Native American women. The model performs best in the populations it was calibrated on. It tends to overestimate risk for some groups and has not been validated equally across all ancestries.

Why is my 5-year risk higher than my friend’s?

Your inputs differ. Age, biopsy history, and family history are the biggest drivers. A friend the same age with no biopsies and no affected relatives will have a much lower number. That’s expected. The model isn’t comparing you to your friend. It’s comparing you to the average woman your age and race.

Does the Gail model include breast density?

No. Breast density is not one of the seven inputs. The Tyrer-Cuzick model and some other risk tools include density. If your mammogram reports dense breasts, mention that to your clinician separately.

Disclaimer

This calculator is for educational purposes only. It estimates risk based on the Gail model (2018 version) and does not diagnose breast cancer or predict whether you will develop it. It isn’t appropriate for women with a personal history of breast cancer, DCIS, LCIS, chest radiation for Hodgkin lymphoma, or a known BRCA1/BRCA2 mutation. The model does not include breast density, alcohol use, hormone therapy, or several other factors that influence risk. Always discuss your results with a qualified healthcare provider before making decisions about screening, prevention, or treatment. This tool does not create a doctor-patient relationship.