How much scalp hair loss is there?
Shade the terminal-hair loss onto four scalp views — or set each percentage directly — and the tool computes the Severity of Alopecia Tool score: each area’s loss weighted by its share of the scalp (top 40%, back 24%, each side 18%), summed to 0–100. Only terminal hair counts; fine vellus regrowth is still scored as loss. Everything stays in your browser.
Shade the maps or set the percentages to begin.
This is an educational self-assessment, not a diagnosis. Small shading differences between assessors are normal, and treatment decisions shouldn’t rest on this number alone — confirm important readings with a dermatologist.
Saving builds a date-stamped history — one score per day, and the trend is what response criteria like SALT 50 actually measure. Pair saved scores with the Photo Tracker for a before-and-after record. Measuring a receding hairline or thinning crown instead? That’s pattern hair loss — a different condition on a different scale — graded in our Hair Loss Stages tool.
Saved only on this device — and browsers erase site data. A history clear, a private window, or Safari's automatic deletion after seven days without a visit will take this log with it. The fix is a free DermApproved account: it backs this up automatically and puts it on every device you sign in to — details in how storage works.
- Hair LossNorwood and Ludwig: Finding Your Stage on the Scales Dermatologists UseTwo staging diagrams drawn in the 1970s still decide what your treatment can realistically achieve — and they encode an uncomfortable deadline.
- Hair LossOne Number Decides Who Gets the New Alopecia Drugs. Learn to Read It.Every JAK inhibitor approved for alopecia areata was licensed on the same endpoint — a SALT score of 20 or less — and the arithmetic behind it is simple enough to follow before somebody else does it for you.
How the SALT calculator works
The Severity of Alopecia Tool (Olsen et al., Journal of the American Academy of Dermatology, 2004) is the standard measure of scalp hair loss in alopecia areata, in clinics and clinical trials alike. The scalp is divided into four areas weighted by their share of its surface — top 40%, back 24%, left side 18%, right side 18% — and the percentage of terminal-hair loss in each is multiplied by that weight and summed to a score from 0 to 100. This tool implements exactly that arithmetic: drag across a scalp view to paint loss cell by cell, or set the percentage with the slider or number box — both drive the same score. The fine-increment painting grid is the SALT II refinement (Olsen & Canfield, 2016) — not a different formula, just a better visual aid for scattered patches, where a thumbprint ≈ 1% of scalp surface is the practical calibration. One rule matters more than any other: only terminal hair counts, so fine vellus regrowth is still scored as loss.
The score maps to the Olsen S-bands — S1 under 25% loss, S2 25–49%, S3 50–74%, S4 75–99% (sub-split S4a/S4b), S5 = 100%, alopecia totalis of the scalp — and change over time is what the number is really for. A drop of at least 50 / 75 / 90 / 100% from your baseline is a SALT 50 / 75 / 90 / 100 response, and the JAK-inhibitor trials set their absolute targets at SALT ≤20 (at least 80% of the scalp covered) and ≤10 (at least 90%). Saved scores stay on this device, show the change between assessments, and can be printed as a one-page report for appointments — add photos via the Photo Tracker for the fuller picture. Note that SALT grades alopecia areata; pattern (androgenetic) hair loss is a different condition staged on the Norwood-Hamilton and Ludwig scales — see the Hair Loss Stages tool for those.
Common questions
Is this the same SALT score dermatologists and clinical trials use?
Same instrument, same arithmetic. SALT (Olsen 2004) divides the scalp into four areas — top 40%, back 24%, each side 18% — and sums percentage terminal-hair loss weighted by each area’s share, giving 0–100. It’s the standard outcome measure in alopecia areata trials: the JAK-inhibitor programs defined treatment success as reaching SALT 20 or below, meaning at least 80% of the scalp covered with hair.
What counts as “loss” when I shade the scalp maps?
Only terminal hair — the thick, usually pigmented hair — counts as coverage. Fine, downy vellus regrowth is still scored as loss, exactly as the original instrument specifies, so a patch of peach fuzz shades the same as bare skin. Regrowth of real terminal hair is what pulls the score down, which is why SALT is the yardstick for tracking whether treatment is working.
How do I score lots of small scattered patches?
Use the painting grid rather than eyeballing a single number — that finer-increment approach is what SALT II (Olsen & Canfield 2016) added, and it isn’t a different formula, just a better visual aid. A practical calibration: your own thumbprint covers roughly 1% of your scalp surface (about 7 cm² in adults), so count thumbprints of involvement per view and shade to match.
Can I use SALT for male- or female-pattern hair loss?
Not meaningfully. SALT was built for alopecia areata, where loss is patchy and can appear anywhere, so it weights all four scalp areas. Pattern (androgenetic) hair loss follows predictable geography — hairline, crown, part-line — and is staged with the Norwood-Hamilton or Ludwig scales instead; our Hair Loss Stages tool covers those. A pattern-loss scalp scored with SALT produces a low number that badly understates the cosmetic reality.
Where do my saved SALT scores go?
Into your own browser’s local storage on this device — nothing is uploaded to DermApproved or anywhere else. The trade-off is fragility: clearing browser data erases the history, so download a backup from My Library once you have scores worth keeping. Pairing each saved score with photos in the Photo Tracker makes the trend much more persuasive at an appointment.