CSS clamp() — Fluid Typography Calculator

Input

Min size (px) Max size (px) Min viewport (px) Max viewport (px)

The quick brown fox jumps over the lazy dog

Viewport: 320 px

Computed size at this viewport: —

clamped output raw linear (without clamp)

Linear interpolation in viewport units. Inside the clamp, the middle expression evaluates to a length that grows linearly with viewport width — passing through (minVw, minSize) and (maxVw, maxSize) by construction.
Slope in vw, intercept in rem. Using rem for the intercept means user font scaling still applies. Hardcoding pixels would override accessibility settings.
clamp() clips the ends. Below minVw the curve is flat at minSize; above maxVw it's flat at maxSize. No media queries needed.
Negative intercept is common and correct. For sharp slopes (large size delta), the intercept is often negative — that's why the math works out at the clamp's lower end. Don't "fix" it.