How to Sharpen a Kitchen Knife (Properly)

A blunt knife is more dangerous than a sharp one. That's not a sharpening enthusiast's sales pitch — it's true. Blunt knives need more force, slip more often, and take longer over food. Getting a proper edge on your kitchen knives is one of the most immediately useful skills you can learn.

The difference between sharpening and honing

These two words get used interchangeably, which causes a lot of confusion. They're not the same thing.

Sharpening removes metal to create a new edge. You do this when a knife is genuinely blunt — it won't cut a tomato without pressing hard, or it slides off rather than biting in.

Honing realigns the existing edge. A knife's edge is microscopically thin, and it bends slightly with use. A honing steel pushes those bent fibres back into alignment. No metal is removed. It's maintenance, not restoration.

Most home cooks need to hone every few uses and sharpen two or three times a year, depending on how much they cook and what surface they're cutting on. Glass and ceramic chopping boards destroy edges fast. A wooden or plastic board is much kinder.

Pull-through sharpeners: quick but costly

Pull-through sharpeners are the little V-shaped devices you drag a blade through. Cheap, quick, extremely popular.

Also fairly aggressive tools that grind away metal at a fixed angle regardless of whether that angle suits your knife. They remove more metal than necessary, shorten the life of a blade substantially, and leave a rough, short-lived edge. Better than nothing, but not good.

If you own a decent knife, a pull-through isn't the tool for it.

The honing steel: your everyday tool

A honing steel (also called a sharpening steel, despite not actually sharpening) should come out far more often than a whetstone. Most good knife sets include one.

To use it: hold the steel vertically with the tip resting on a folded cloth or chopping board. Draw the blade down the steel at a consistent angle — around 15 to 20 degrees from the steel — from heel to tip, alternating sides. Five or six strokes per side before each use, or whenever the knife starts to feel sluggish.

The angle is the key variable. Most European knives are ground at 20 degrees; many Japanese knives at 15. If you're not sure, 17 degrees is a reasonable middle ground. You can buy angle guides while you're learning.

Whetstones: the right tool for actual sharpening

A whetstone is a flat abrasive block you use to grind a new edge onto a blade. It takes more time and skill than a pull-through, and gives a vastly better result.

Whetstones come in different grits. Lower numbers are coarser and remove more metal — start here if the knife is genuinely blunt or damaged. Higher numbers are finer and refine the edge.

A practical grit progression for most home cooks:

• 400–600 grit — for blunt or chipped knives
• 1000 grit — general sharpening, the grit you'll use most
• 3000–6000 grit — polishing and refining the edge

You don't need to start at 400 if the knife is just dull, not damaged. Most sharpening sessions are 1000 grit followed by a 3000 or 6000 finish.

Soak the stone in water for a few minutes before use (check the manufacturer — some just need a splash). Lay the blade on the stone at your target angle and make smooth, even strokes. The grey slurry that builds up is normal and useful; don't wash it off mid-session.

The angle: 15 to 20 degrees

Holding a consistent angle is the hardest part of freehand sharpening and the most important. Even a few degrees of variance undoes the work.

A useful cheat: 15 degrees is roughly the gap you'd get if you slid a matchbook under the spine of the knife while the edge rests on the stone. 20 degrees is closer to two matchbooks. This sounds rough, but it's genuinely how most people learn.

An angle guide clipped to the blade removes the guesswork entirely and is worth buying while you're developing the feel.

The paper test

Hold a sheet of printer paper by the top edge and draw the knife through it. A sharp knife slices cleanly. A moderately sharp knife tears or snags. A blunt knife buckles the paper without cutting.

For a more demanding test, try cutting through the paper at an angle, or check whether the knife can shave hair off your forearm. These tests sound theatrical but give instant, honest feedback.

How often should you sharpen?

Most home cooks sharpen far less often than they should. A knife that cuts easily is quicker, safer, and more enjoyable to use.

Hone before each use or at least every few sessions. Sharpen when honing stops restoring the edge — usually a few times a year for regular home cooking. If you're cutting a lot of hard vegetables or working with a cheap blade, more often.

The other variable is what you're cutting on. Glass boards are edge killers. Switch from glass to wood and you'll find your knives hold an edge noticeably longer.

Related: How to make sourdough bread · Coffee from bean to cup · Why learning a physical skill is worth your time

The airgap.life knife sharpening course covers stone selection, angle technique, and how to restore a knife that's been neglected for years — with enough detail to get a working edge on the first session.