How severe is my psoriasis?
Grade redness, thickness and scaling to set a self-assessed Global Assessment (0–4), estimate the body surface area involved, and get PGA × BSA — a fast, validated 0–400 severity product used as a practical alternative to the PASI. Save it over time and the tool flags PGA×BSA-50 / 75 / 90 treatment-response milestones. Everything stays on this device.
Global Assessment
Grade the three plaque signs; the overall grade is their average0.0 → PGA0 in sync No signs of psoriasis; post-inflammatory pigmentation may remain.
Body surface area involved
One palmar surface (palm + fingers) ≈ 1% of body surfaceBSA must be between 0 and 100%.
Scattered plaques hard to eyeball? Paint a body map in the BSA calculator — count palms or use the Rule of Nines, and a saved map prefills this field automatically.
The product is reported as a continuous 0–400 measure — no fixed severity bands are applied beyond the PGA category, consistent with the source literature. PGA×BSA-75 (a ≥75% reduction from baseline) is the recognised response endpoint, analogous to PASI-75.
This is an educational self-assessment — a self-scored adaptation of a physician-rated instrument — not a diagnosis. Share the result with your GP or dermatologist rather than acting on it alone.
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 Dermington account: it backs this up automatically and puts it on every device you sign in to — details in how storage works.
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How the PGA × BSA score works
PGA × BSA multiplies severity by extent: a static Physician’s Global Assessment — here self-assessed — from 0 (clear) to 4 (severe), times the percentage of body surface area involved, for a continuous product from 0 to 400. The overall PGA is conventionally taken as the average of three plaque signs — erythema (redness), induration (thickness), and scaling — each graded 0–4 against published anchors, rounded to the nearest grade; you can override the derived grade if your overall impression differs. The measure was validated as a practical alternative to the PASI (Walsh JA et al., Journal of the American Academy of Dermatology, 2013), with post-hoc analyses of the PRISTINE/PRESTA trials (Psoriasis: Targets and Therapy, 2018) and RAPID-PsA (Journal of Rheumatology, 2018) confirming it tracks the PASI closely while taking a fraction of the time to score.
For the extent half, your own palm including the fingers covers roughly 1% of your body surface — count palm-equivalents of involved skin, or paint the figures in our BSA calculator and let a saved map prefill this tool. The raw product carries no fixed severity bands beyond the PGA category itself, consistent with the source literature; its real power is the trend. Save a score whenever your skin changes or treatment starts, and the history flags PGA×BSA-50, -75, and -90 — reductions of at least 50%, 75%, or 90% from your first saved score, with the -75 threshold recognised as the response endpoint analogous to PASI-75. Everything runs and stays on this device; nothing is uploaded anywhere.
Common questions
Is PGA×BSA as accurate as the PASI score my dermatologist uses?
Close enough to be genuinely useful — the product correlates strongly with the PASI in validation studies (Walsh and colleagues, Journal of the American Academy of Dermatology, 2013, plus post-hoc analyses of the PRISTINE/PRESTA and RAPID-PsA trials) while taking a fraction of the time to score. The PASI remains the trial gold standard, but PGA×BSA was proposed precisely because it captures the same severity-times-extent idea with two inputs instead of sixteen. For tracking your own skin between appointments, that trade is a bargain.
What do the five PGA grades actually look like on skin?
Each grade is anchored to the three things a plaque does: redness, thickness, and scale. Grade 0 is clear (only leftover pigmentation may remain), 1 is almost clear — no thickening, faint residual redness, minimal scale. Mild (2) means slight thickening with light redness and fine scale, moderate (3) means all three signs are clearly present, and severe (4) is marked thickening with bright or deep redness and thick, coarse scale. Grade each sign honestly on your worst representative plaques, and the tool averages them into the overall grade.
How do I estimate my body surface area without just guessing?
Your own palm — including the fingers — covers roughly 1% of your body surface, so counting palm-equivalents of involved skin gets you a defensible percentage fast. That palm method is most reliable for limited-to-moderate involvement; if plaques are widespread or scattered, the painted body map in our BSA calculator is steadier, and a saved map from that tool prefills this one automatically.
What counts as a real treatment response on this score?
The recognised endpoint is PGA×BSA-75 — a 75% or greater reduction of the product from your baseline score, directly analogous to PASI-75 in psoriasis trials. Drops of 50% and 90% are also tracked as milestones. Your saved history flags these automatically against your first saved score, which is exactly the kind of evidence a dermatologist wants when judging whether a treatment is working.
Where does my score history end up?
In your own browser’s local storage on this device — nothing is transmitted to Dermington or anywhere else. The flip side of that privacy is fragility: clearing browser data erases the history, and it won’t follow you to another device unless you download a backup from Your data. If you’re building a treatment-response record worth keeping, back it up.