Kerning Adjustment Calculator

Optical kerning spacing adjustment estimate.

Font size (px)

Shape category (1–5)

Tracking (em)

Units per em (UPM)

Tab to move between fields

Kern value (UPM units)

-50

Kern value (px)-0.8

Kern value (em)-0.05

Effective spacing (px)-0.8

Effective spacing (em)-0.05

Tightness score75/100

Display Size Warning0

How to Use This Calculator

How the result changes with Units per em (UPM)

Font size (px): Font size at which kerning will be applied.
Shape category (1–5): Character pair shape: 1 = straight-straight (HH), 2 = straight-round (HO), 3 = round-round (OO), 4 = open-diagonal (To), 5 = extreme (AV, Ty).
Tracking (em): CSS letter-spacing value in em. Positive = looser, negative = tighter.
Units per em (UPM): Font's units-per-em. Most fonts use 1000 (PostScript) or 2048 (TrueType).

Kern value (UPM units): Kerning adjustment in font units. Negative = tighter.
Kern value (px): Kerning adjustment in pixels at your font size.
Kern value (em): Kerning adjustment as a fraction of 1em.
Effective spacing (px): Combined tracking + kerning adjustment in pixels.
Effective spacing (em): Combined tracking + kerning in em — use as CSS letter-spacing.
Tightness score: Visual tightness rating: 0 = very loose, 50 = neutral, 100 = very tight.

Identify Input Parameters
4 parameters
Font size (px) = 16, Shape category (1–5) = 3, Tracking (em) = 0, Units per em (UPM) = 1000 = 4 input(s) provided
Calculate Kern value
Kern value
-50 = -50
Calculate Kern value
Kern value = kernFraction * fontSizePx
-0.8 = -0.8
Calculate Kern value
-0.05 = -0.05