How to Sharpen a Santoku Knife: A Step-by-Step Guide

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Updated August 2026 · 9 min read · UK Japanese-steel knife specialists

Sharpen a santoku on a whetstone at roughly 15 degrees per side — about the width of two stacked £1 coins under the spine. Work the whole edge on a 1000-grit stone until you can feel a burr along the far side, repeat on the other face, then refine on 3000 and finish on 8000 if you have it. Fifteen minutes, start to finish.

A santoku is not a difficult knife to sharpen. Its edge is nearly straight for most of its length, which means you can keep the blade flat against the stone instead of rocking through a curve the way you do with a chef's knife. If you have been putting this off, the santoku is a good knife to learn on.

The one thing that trips people up is the angle. Most santoku knives — including every santoku in our santoku range — are ground far thinner than a European knife, and sharpening them at a European angle quietly ruins the thing you paid for. Below is the whole process, plus the mistakes that cost people an edge.

What you actually need

Very little. A double-sided whetstone, water, a flat surface and a damp cloth to stop the stone sliding. That is the entire kit.

• A whetstone, ideally two grits. 1000 grit does the actual sharpening; 3000 and up refines and polishes. A combination stone gives you both faces in one block. Our 400/1000 and 3000/8000 stone set covers repair through to polish.
• Water. These are water stones, not oil stones. If you are unsure which you own, our guide on telling an oil stone from a water stone settles it in a minute.
• A non-slip base. A damp tea towel under the stone is enough. A stone that shifts mid-stroke is how people cut themselves.
• Something to test on. A sheet of paper, or a tomato — a properly sharpened santoku will start a tomato skin under its own weight.

You do not need an electric sharpener, a pull-through, or a jig. And a honing steel is not a sharpener — it straightens an edge that has rolled over, which is a different job. We cover the distinction in whetstone vs honing steel.

Do you need to soak the stone?

Coarse and medium stones — 400 and 1000 grit — soak. Drop the stone in water and leave it until the stream of bubbles stops, usually five to ten minutes. Fine finishing stones at 3000 and above generally do not want a long soak; splashing water onto the surface as you work is enough, and over-soaking a fine stone can soften it. If you want the longer version, we wrote a whole piece on how long to soak a whetstone.

The angle: why 15° matters on a santoku

A typical European kitchen knife is ground at around 20° per side. Japanese-style double-bevel knives like the santoku are usually somewhere around 15° per side — sometimes a touch less. That shallower angle is most of the reason a santoku feels so much keener than the knife it replaced.

The steel is what makes that possible. Our santoku knives are forged around a high-carbon stainless Japanese steel core — VG10 in most of the range — hardened to roughly 60–61 HRC. Harder steel supports a thinner edge without folding over. Put a 20° bevel on it and you have thrown that advantage away; you now own an expensive knife that cuts like an ordinary one.

Fifteen degrees is hard to visualise, so use the coin trick: lay the blade flat on the stone, then lift the spine until you could just slide two stacked £1 coins underneath. On a 7-inch santoku that is close enough to 15°. Hold that height and stop thinking about degrees.

If you want the full reasoning — including where single-bevel knives differ — see our guide to the correct Japanese knife sharpening angle.

How to sharpen a santoku knife, step by step

1. Soak and set up

Soak the 1000-grit face until the bubbles stop. Set the stone on a damp cloth on a worktop at hip height, long edge running away from you. Stand square to it. Keep a small bowl of water beside you.

2. Find your angle and grip

Pinch the blade just ahead of the handle with your dominant hand — thumb on the spine, forefinger on the flat. Lay the edge on the far end of the stone, lift the spine to the two-coin height, and rest two or three fingertips of your other hand flat on the blade, near the edge. Those fingertips supply the pressure; the pinching hand only controls the angle.

3. Work the heel section

Divide the edge into three: heel, middle, tip. Start at the heel. Push the blade away from you along the stone with moderate pressure, then draw it back with almost none — the cutting happens on the push. Ten to fifteen strokes, then check.

4. Feel for the burr

This is the only reliable signal that you have actually sharpened anything. Run a fingertip across the edge — never along it — on the opposite face. When the bevel reaches the very apex, a fine wire of displaced steel folds over onto the far side. That is the burr. If you cannot feel it, keep going; you have not reached the edge yet. Our explainer on what a burr is and how to feel one goes into more detail.

5. Move along the blade

Shift to the middle third, repeat until the burr appears there, then the tip. A santoku's near-straight edge makes this simple — only in the last inch or so, where the spine curves down to meet the edge, do you need to lift the handle very slightly to keep contact. Keep the stone wet throughout; the grey slurry that builds up is doing useful work, so don't rinse it away.

6. Flip and repeat

Turn the knife over and do exactly the same on the other face, again in thirds, again until you raise a burr the other way. A santoku is double-bevelled, so both sides get equal treatment. Roughly equal stroke counts keep the edge centred.

7. Refine, then remove the burr

Move to the 3000-grit face and repeat both sides with lighter pressure and fewer strokes — maybe five or six per section. Finish on 8000 if you have it. Then take the burr off: a few feather-light alternating strokes, one side then the other, pressure barely more than the blade's own weight. Some people finish by drawing the edge through the end grain of a wooden board or a few passes on a strop.

8. Wash, dry, test

Rinse the blade in warm water, dry it immediately and completely, and test it. A sharp santoku will slice cleanly through a sheet of printer paper held in the air, and will bite into a tomato skin without you pressing. If it slides across the skin, you probably left a burr on — a few more light alternating strokes will sort it.

Five mistakes that cost people an edge

1. Sharpening at 20°. The single most common one, usually because someone learned on a European knife. It works — it just gives you a duller santoku.
2. Stopping before the burr. Twenty polite strokes on a fine stone feels productive and achieves nothing if the bevel never reached the apex. No burr, no sharpening.
3. Leaning on it. Heavy pressure on a hard, thin edge risks chipping and produces a ragged burr that's hard to remove. Let the abrasive do the work.
4. Using a pull-through or electric sharpener. Most are fixed at a Western angle and remove far more steel than a stone does. If you are considering one, read whether electric sharpeners are bad for Japanese-steel knives first.
5. Letting it get truly blunt first. A quick touch-up on a fine stone every few weeks takes two minutes. Waiting until nothing cuts means starting at 400 grit and removing real metal. Our guide on how often to sharpen has sensible intervals.

The kit we sell for this

Everything below is what we'd actually reach for. If you already own a decent 1000-grit stone, you don't need anything from us — just use it properly.

And if the santoku you've been sharpening turns out to be softer steel that won't hold an edge no matter what you do, these are the two we'd point you at:

Which grit, and when

Grit	Job	When to reach for it
400	Repair	Visible chips or a rolled tip. Removes real metal — use sparingly.
1000 — the one that matters	Sharpen	Sets the actual edge and raises the burr. If you own one stone, own this.
3000	Refine	Cleans up the 1000-grit scratches and tightens the apex.
8000	Polish	Optional. Makes a keen edge glide rather than bite. Nice, not essential.

Not sure what to buy? Our guide on what grade of whetstone to buy works through it, or browse the sharpening stones we stock.

FAQ

What angle should you sharpen a santoku knife at?

Around 15 degrees per side, giving roughly a 30-degree included edge. That is noticeably shallower than the 20 degrees per side typical of European knives, and it is what makes a santoku feel keen. Lift the spine until you could just slide two stacked £1 coins beneath it and hold that height.

Is a santoku knife single or double bevel?

Double bevel. Santoku knives are sharpened on both faces, so you work each side roughly equally on the stone. Traditional single-bevel knives such as the usuba and yanagiba are sharpened on one face only and need a different technique.

How often should you sharpen a santoku knife?

For a home cook using it most days, a full whetstone sharpening every two to three months is usually plenty, with a few passes on a honing steel weekly in between. Heavy daily use shortens that. The honest answer is to sharpen when it stops biting into a tomato skin under its own weight, not on a calendar.

Can you sharpen a santoku with an electric sharpener?

You can, but most consumer electric and pull-through sharpeners are fixed at a Western angle of about 20 degrees per side and remove a lot of steel. Used on a hard, thin Japanese-steel edge that means a blunter angle and a shorter knife life. A 1000-grit whetstone costs less and does a better job.

How do you know when the santoku is sharp enough?

Two tests. Hold a sheet of printer paper by one corner and slice down through it — a sharp edge cuts cleanly without tearing or snagging. Then rest the blade on a tomato and draw it back with no downward pressure; it should break the skin immediately. If it skates, you have likely left a burr attached.

Does sharpening a santoku differ from sharpening a chef's knife?

Only in the movement. A santoku's edge is nearly straight, so the blade stays flat on the stone through most of its length. A gyuto or European chef's knife has a pronounced belly, so you have to lift the handle progressively as you work towards the tip to keep the edge in contact. The angle and the burr test are identical.

Should you sharpen a new santoku straight out of the box?

Not usually. A knife from a specialist arrives sharpened and ready to use, and taking a stone to it immediately just removes steel for nothing. Use it, and sharpen it when performance drops off — which on a hardened stainless VG10 edge may be several months away.

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