Knife Sharpening Angles: 15° vs. 20° – What’s the Difference for Kitchen Knives?
Before we compare 15° and 20°, we need to clear up a common point of confusion. When knife manufacturers or sharpening tool producers mention a "15-degree edge," they are almost always referring to the angle per side – the angle between one blade face and the vertical centerline of the knife.
The total inclusive edge angle is the sum of both sides. A 15° per-side edge has a total inclusive angle of 30°. A 20° per-side edge totals 40°.
Most commercial sharpening tools specify the per-side angle in their documentation. Always confirm which measurement is being used before selecting a sharpener.