How this calculator works
EASI combines an area band and four clinician-rated signs in each of four body regions. This follows the Hanifin index and the HOME case-report forms. For each sign, the permitted values are 0, 1, 1.5, 2, 2.5 and 3; 0.5 is not an allowed rating. At age 8 the older-child/adult weights apply. Assess the inflamed eczema area using the official protocol, not unrelated dryness or pigmentation. The form rejects a zero-area region with nonzero signs and an involved region with no recorded signs. It reports the numerical index without attaching treatment advice. The result is an estimate for information only and is not medical advice.
Formula
Regional contribution = area score × (erythema + oedema/papulation + excoriation + lichenification) × age-specific weight. EASI = sum of four contributions. Weights in head, arms, trunk, legs order: age under 8, 0.2, 0.2, 0.3, 0.3; age 8 or older, 0.1, 0.2, 0.3, 0.4.
Worked example
At age 8 or older, head area score 2 and four sign scores of 1 give 2 × 4 × 0.1 = 0.8 if other regions are clear. The same findings under age 8 give 1.6. All regions at area score 6 with all signs 3 total 72 in either age group.
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Frequently asked questions
Which weight applies on the eighth birthday?
Use the 8-years-or-older group. The younger form is specifically for patients under 8.
Can I enter 0.5 for a mild sign?
No. The HOME forms allow 1.5 and 2.5 as intermediate ratings, but a present sign scores at least 1.
Is this a whole-body percentage input?
No. Each region has its own percentage involvement and area band, then its own body-region weight.