The Schnur Sliding Scale
The Schnur Sliding Scale is the reference table insurers use to judge whether a breast reduction is reconstructive or cosmetic. It comes from a 1991 study by plastic surgeon Dr. Paul Schnur and maps body surface area to a minimum weight of breast tissue, in grams per breast, that must be removed for the operation to be argued as medically necessary.
Nobody memorizes it. Surgeons look it up at every breast reduction consult, patients meet it the first time an insurer mentions coverage, and the number changes with every body. This page keeps the complete published table in one place, with the body surface area calculation built in.
Calculate your BSA
The scale is indexed by body surface area, a number computed from height and weight. It is related to BMI but it is not BMI. Enter both measurements and the calculator finds your place on the table below.
The complete table
Minimum grams of tissue per breast by body surface area, as published from the original study and printed in insurer medical policies. In the study, removals above the 22nd percentile for body size were associated with medical rather than cosmetic motivation, and that line became the working threshold insurers use.
| Body surface area (m²) | Minimum grams per breast |
|---|---|
| 1.35 | 199 |
| 1.40 | 218 |
| 1.45 | 238 |
| 1.50 | 260 |
| 1.55 | 284 |
| 1.60 | 310 |
| 1.65 | 338 |
| 1.70 | 370 |
| 1.75 | 404 |
| 1.80 | 441 |
| 1.85 | 482 |
| 1.90 | 527 |
| 1.95 | 575 |
| 2.00 | 628 |
| 2.05 | 687 |
| 2.10 | 750 |
| 2.15 | 819 |
| 2.20 | 895 |
| 2.25 | 978 |
| 2.30 | 1,068 |
| 2.35 | 1,167 |
| 2.40 | 1,275 |
| 2.45 | 1,393 |
| 2.50 | 1,522 |
| 2.55 | 1,662 |
| 2.60 | 1,806 |
| 2.65 | 1,972 |
| 2.70 | 2,154 |
| 2.75 | 2,352 |
| 2.80 | 2,568 |
| 2.85 | 2,804 |
| 2.90 | 3,061 |
| 2.95 | 3,343 |
| 3.00 | 3,650 |
| 3.05 | 3,985 |
| Body surface area (m²) | Minimum grams per breast |
|---|---|
| 3.10 | 4,351 |
| 3.15 | 4,750 |
| 3.20 | 5,186 |
| 3.25 | 5,663 |
| 3.30 | 6,182 |
| 3.35 | 6,750 |
| 3.40 | 7,369 |
| 3.45 | 8,045 |
| 3.50 | 8,783 |
| 3.55 | 9,589 |
| 3.60 | 10,468 |
| 3.65 | 11,428 |
| 3.70 | 12,476 |
| 3.75 | 13,619 |
| 3.80 | 14,867 |
| 3.85 | 16,230 |
| 3.90 | 17,717 |
| 3.95 | 19,340 |
| 4.00 | 21,112 |
| 4.05 | 23,045 |
| 4.10 | 25,156 |
| 4.15 | 27,459 |
| 4.20 | 29,972 |
| 4.25 | 32,716 |
| 4.30 | 35,710 |
| 4.35 | 38,977 |
| 4.40 | 42,543 |
| 4.45 | 46,435 |
| 4.50 | 50,682 |
| 4.55 | 55,316 |
| 4.60 | 60,374 |
| 4.65 | 65,893 |
| 4.70 | 71,915 |
| 4.75 | 78,487 |
| 4.80 | 85,658 |
Source: Schnur PL, et al. Reduction mammaplasty: cosmetic or reconstructive procedure? Annals of Plastic Surgery. 1991;27(3):232–237. Individual insurance plans publish their own criteria and may apply the scale differently; your plan document governs.
How the scale is used at consultation
At a breast reduction consultation, Dr. Day estimates the tissue weight your reduction would remove and reads it against your body surface area and your insurer's published policy. That produces an honest early answer to the coverage question: likely to qualify, unlikely, or close enough that documentation will decide it.
The practice navigates pre-authorization with you, including plans like Premera and Regence. Coverage is never guaranteed, and you will hear a realistic read rather than an optimistic one.
What insurers want documented
- Medical records of the symptoms your breast size causes: neck, back, or shoulder pain, grooving where bra straps sit, rashes in the fold beneath the breast.
- A provider's note recommending reduction as treatment.
- The conservative measures you have already tried, such as physical therapy, supportive garments, or medication.
- Photos, when the plan requires them.
The more of that history that already exists in your records, the shorter the process tends to be.
Common questions
Does meeting the Schnur scale guarantee insurance coverage?
No. The scale is one criterion among several. Insurers also want documented symptoms such as neck, back, or shoulder pain, and evidence of conservative measures you have already tried. Each plan publishes its own policy, and some use different thresholds entirely. The practice reads your plan with you and gives you an honest assessment before you start the paperwork.
What BMI do I need for an insurance-covered breast reduction?
There is no universal BMI requirement. The Schnur scale itself uses body surface area rather than BMI, but many insurance policies add their own BMI criteria on top of it. Your specific plan's policy is what governs, and reading it is part of the consultation.
What if my body surface area falls between two rows?
The published table moves in steps of 0.05. Insurers state in their own policies how they treat values between rows, and practices document the calculation they used. At consultation the estimate is made from your measured height and weight against your plan's actual policy language.
How is body surface area calculated?
From height and weight. A common method is the Mosteller formula: the square root of height in centimeters times weight in kilograms divided by 3,600. It is a different number from BMI, though both come from the same two measurements.
The full picture of the operation itself, from incision patterns to recovery, is on the breast reduction page.
Get a straight answer on coverage
A consultation reads your measurements against your own plan's policy. Call (425) 818-8991 or schedule online.
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