BI-RADS Categories: Your Mammogram Score, Decoded

What does BI-RADS actually stand for?

BI-RADS stands for the Breast Imaging Reporting and Data System, a shared scoring language radiologists use to summarize a mammogram in a single number. Developed by the American College of Radiology, the system turns a complex image into a category from 0 to 6 so that every report points to a clear next step. According to the National Cancer Institute, standardized reporting helps clinicians and patients understand results and compare them from year to year 1Ref 1National Cancer Institute (PDQ Screening and Prevention Editorial Board) (2025).Breast Cancer Screening.NCI patient screening page supporting that standardized mammogram reporting aids comparison over time and that most women recalled for extra testing after a mammogram do not have cancer. The mammogram timing and screening age shape how often it is repeated: average-risk women are offered screening from age 40, every 1 to 2 years 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that breast density and personal and family risk are factors clinicians weigh when recommending screening for average-risk women. Mammography is also one of the tests folded into the recommended well-woman screening schedule 3Ref 3American College of Obstetricians and Gynecologists (2018).ACOG Committee Opinion No. 755: Well-Woman Visit.ACOG committee opinion placing mammography within the recommended well-woman screening schedule.

What do the numbers 0 through 6 mean?

Each BI-RADS number from 0 to 6 maps to a specific level of concern and a recommended next step.

• 0 - Incomplete: more imaging or older films are needed before scoring
• 1 - Negative: nothing notable to report
• 2 - Benign: a clearly harmless finding, such as a simple cyst
• 3 - Probably benign: more than 98% likely not cancer, usually watched
• 4 - Suspicious: roughly a 2% to 95% chance of cancer, biopsy often advised
• 5 - Highly suggestive: at least 95% likely cancer, biopsy advised
• 6 - Known cancer: a biopsy has already confirmed a malignancy

The two lowest categories are the everyday normal results most women receive. Your report may also split a category 4 into 4A, 4B, and 4C to signal how suspicious the finding looks, which helps the radiologist decide whether a biopsy is worth it.

Which categories need more testing?

Categories 0, 3, 4, and 5 each send you down a different follow-up path, while 1 and 2 return you to routine screening. A BI-RADS 0 result means the radiologist needs extra views or an ultrasound before deciding. A probably-benign BI-RADS 3 is usually rechecked in about 6 months rather than biopsied. Categories 4 and 5 typically lead to a biopsy that samples the tissue. According to the National Cancer Institute, only about 1 in 10 women are called back after a mammogram, and most do not turn out to have cancer 1Ref 1National Cancer Institute (PDQ Screening and Prevention Editorial Board) (2025).Breast Cancer Screening.NCI patient screening page supporting that standardized mammogram reporting aids comparison over time and that most women recalled for extra testing after a mammogram do not have cancer. The category simply tells you which of these paths applies to your report.

Where does breast density fit in?

Every mammogram report also assigns a breast-density grade that is separate from the BI-RADS number. Density describes how much fibroglandular tissue appears compared with fat, and dense tissue noted on your letter can make cancers harder to see. The four density categories running from A to D put C and D in the dense group. According to the American College of Obstetricians and Gynecologists, density is one factor clinicians weigh when they recommend screening 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that breast density and personal and family risk are factors clinicians weigh when recommending screening for average-risk women. Density is often higher before menopause and tends to fall with age, so the same person may watch her grade shift across the years. The density line and the BI-RADS number answer different questions, so reading them together gives the fullest picture of one mammogram.

When a BI-RADS result needs a radiologist

A BI-RADS 4 or 5, or a score that does not match a lump you can feel, is a reason to talk with a breast specialist without long delay. Even with a reassuring number, a new breast lump worth checking or a change you notice while checking your breasts deserves attention, because mammograms miss a small share of cancers. According to the American College of Obstetricians and Gynecologists, screening works best when tailored to your personal and family risk 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that breast density and personal and family risk are factors clinicians weigh when recommending screening for average-risk women. Gale can help you prepare questions for that conversation and keep your results in one place. Keeping a copy of each year's report also lets a new clinician compare your scores over time.