You don't need a whetstone or years of practice to sharpen a kitchen knife. Here's a simple method that works for most straight-edge knives.
1. Check whether your knife is actually blunt
Try the tomato test: rest the knife on a tomato and draw it back gently. A sharp knife bites into the skin straight away. A blunt one slides or squashes. You can also try slicing a sheet of printer paper held in the air.
2. Pick your angle
Use 15° for thin Japanese-style knives and 20° for most Western chef's knives. If you're not sure, use 20°. (Read more: 15° vs 20° knife angle.)
3. Hold the angle consistently
This is where most people go wrong. The edge only forms if every stroke hits the same angle. A rolling sharpener's magnetic block solves this: rest the blade against the magnet and it stays put.
4. Sharpen, then polish
- Roll the coarse (diamond) disc along the edge 10–20 times.
- Flip the knife and repeat on the other side.
- Switch to the fine disc and do 5–10 lighter passes on each side to polish the edge.
5. Clean and test
Wipe the blade to remove any metal dust, then repeat the tomato or paper test.
How often should you sharpen?
Most home cooks need a full sharpen every 1–3 months, with a quick fine-disc touch-up in between. Cutting on wood or plastic boards (not glass or stone) keeps edges sharp for longer.
Want the easy way? The Sharpsmith rolling knife sharpener holds the angle for you, so it takes minutes, not practice.