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The web workbench

Calculate image dimensions, check contrast and estimate transfer size. Everything runs in your browser.

Calculations run locally. No photos, passwords or other data are uploaded.

Image dimensions

4000 × 3000 → 1600 × 1200 reduces the pixel count by 84%; check actual file size separately after export.

Text contrast

Black #000000 on white #FFFFFF has 21:1 contrast. WCAG AA requires at least 4.5:1 for normal text and 3:1 for large text. Large means at least 18 pt, or 14 pt bold.

Image budget

10 images at 200 KB total 2 MB. At 10 Mbps, transfer alone theoretically takes 1.6 s, excluding latency, decoding and other resources.

Sources and next steps

H₂ = H₁ × W₂ / W₁

MB = N × KB / 1000; s = MB × 8 / Mbps

WCAG — Contrast Minimum