Testing Knife Sharpness

By Cook's Illustrated Published July 2015

What's the best way to determine when your knife needs sharpening?

Owning a knife sharpener makes tuning up your knife easy, but how do you know when it’s time? The best way to tell if a knife is sharp is to put it to the paper test. Holding a sheet of paper (basic printer/copy paper is best) firmly at the top with one hand, draw the blade down through the paper, heel to tip, with the other hand. The knife should glide through the paper and require only minimal pushing. If it snags, try realigning the blade’s edge using a honing, or sharpening, steel and then repeat the test. If the knife still doesn’t cut the paper cleanly, use your sharpener. Repeat the paper test to make sure the knife is properly sharpened; if it catches on the paper, note where along the blade it happens. You can minimize the amount of metal removed by focusing on just this section of the blade to fine-tune the sharpening (just make sure you don’t overdo it and end up making the blade uneven).

MAKING THE CUT: A properly sharpened knife will glide through paper with minimal pushing, no snagging.