GAGS Calculator

Global Acne Grading System — Doshi, Zaheer & Stiller, 1997

Purpose
Rapid global grading of acne severity: each location is scored by its most severe lesion type and weighted by its surface area and pilosebaceous density.
Population
Adolescents and adults with acne vulgaris of the face, chest and upper back. Not designed for acne conglobata/fulminans scarring assessment.
Formula
GAGS = Σ (location factor × lesion grade) · Factors: forehead 2, right cheek 2, left cheek 2, nose 1, chin 1, chest & upper back 3 · Grade: 0 none, 1 ≥ 1 comedone, 2 ≥ 1 papule, 3 ≥ 1 pustule, 4 ≥ 1 nodule · Range 0–44
Severity thresholds
Doshi 1997: 0 none · 1–18 mild · 19–30 moderate · 31–38 severe · ≥ 39 very severe
📍 Lesion grade by location

For each location, select the grade of the most severe lesion present. The local score is factor × grade.

0No lesions
1≥ 1 comedone
2≥ 1 papule
3≥ 1 pustule
4≥ 1 nodule
Running total 0 / 44
ℹ️ GAGS grades the predominant lesion type, not lesion counts. For patients starting isotretinoin, plan the cumulative dose with the isotretinoin dose calculator; in women with hirsutism or irregular cycles, see the PCOS diagnostic guide.
📚 References
  1. Doshi A, Zaheer A, Stiller MJ. A comparison of current acne grading systems and proposal of a novel system. Int J Dermatol. 1997;36(6):416–8. doi:10.1046/j.1365-4362.1997.00099.x
  2. Nast A, Dréno B, Bettoli V, et al. European evidence-based (S3) guideline for the treatment of acne — update 2016 — short version. J Eur Acad Dermatol Venereol. 2016;30(8):1261–8. doi:10.1111/jdv.13776
  3. Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2024;90(5):1006.e1–30. doi:10.1016/j.jaad.2023.12.017
Clinical decision support only. This tool is intended to assist clinical assessment and does not replace professional judgment. Always interpret results in the context of the individual patient.