It is crucial to keep knives sharp so that they cut through food with less slippage. Dull knives are dangerous because a dull blade requires more force to do the job and so has a higher chance of slipping and missing the mark. Plus, poorly cut food will not cook properly. A sharp knife will produce food that is evenly cut and therefore will cook at an even rate. We'll show you how to sharpen kitchen knives—it's one of the easiest ways to instantly improve your cooking.

What You'll Learn

How to Tell If Your Knife is Sharp Enough

Put the blade to the paper test

Even the best knives will dull over time with regular use. To determine if your knife needs sharpening, put it to the paper test. Hold a folded, but not creased, sheet of newspaper by one end. (You can also use a single sheet of basic printer/copy paper.) Lay the blade against the top edge at an angle and slice outward. If the knife fails to slice cleanly, try steeling it (see below). If it still fails, it needs sharpening.

A Scientific Glimpse: What a Sharp and Dull Knife Look Like Up Close

In our knife sharpener research, we examined blades—from sharp (smooth and sharp) to dull (all chewed up)—under a high-powered laboratory microscope at the Massachusetts Institute of Technology’s Department of Materials Science and Engineering.

When to Use a Knife Sharpening Steel

A so-called sharpening steel, the metal rod sold with most knife sets, doesn’t really sharpen a knife, but rather it hones the edge of a slightly dulled blade. Sweeping the blade along the steel realigns the edge. Throughout this motion, make sure to maintain a 15-degree angle between the blade and the steel.

How to Use a Knife Sharpening Steel

Step 1

To safely use a steel, hold it vertically with the tip firmly planted on the counter. Place the heel of the blade against the tip of the steel and point the knife tip slightly upward. Hold the blade at a 15-degree angle away from the steel.

Step 2

Maintaining light pressure and a 15-degree angle between the blade and the steel, slide the blade down the length of the steel in a sweeping motion, pulling the knife toward your body so that the middle of the blade is in contact with the middle of the steel.

Step 3

Finish the motion by passing the tip of the blade over the bottom of the steel. Repeat this motion on the other side of the blade. Four or five strokes on each side of the blade (a total of eight to ten alternating passes) should realign the edge.

When to Use a Knife Sharpener

If your knife is quite dull, you’ll need to reshape its edge. This requires removing a fair amount of metal—more than you could ever remove with a steel. To restore a very dull knife, you have three choices: You can send it out; you can use a whetstone (tricky for anyone but a professional); or—the most convenient option—you can use an electric or manual sharpener.

All About Electric Knife Sharpeners

How to Use: These machines are very easy to use. With electric sharpeners, the abrasives are on motorized wheels that spin against the blade. Always follow the manufacturer's instructions. In general: Turn on the sharpener, hold your knife securely but lightly (no need to press down hard; the machine does the work for you), and pull the blade through the desired slots slowly and smoothly. Alternate sides for sharpening both sides of your blade. Our favorite electric model features a dedicated slot for heavy damage, and it required only 76 strokes to make a severely damaged knife look and cut like a brand-new blade. This slot can narrow the angle of a traditional Western blade, converting it from 20 degrees to 15. We tested that claim by running a brand-new 20-degree chef’s knife through it for 20 strokes on either side of the blade (per manufacturer’s directions)—and it was significantly sharper than a second new copy of that knife.


  • Spring-loaded guides restrict the knife’s movement so that the entire edge makes steady contact with the abrasive at a precise angle.
  • The aggressive first slot can quickly repair extensive damage and narrow a 20-degree Western knife to a sharper 15-degree edge.
  • This sharpener features multiple grinding slots, each with a different coarseness of blade to control the amount of sharpening.


  • Cannot be used for knives that sport a full bolster, as the entire blade cannot be run through the sharpener (creating an unevenly shaped blade).
  • Relatively expensive.

Our favorite electric knife sharpener: Chef'sChoice Trizor XV Knife Sharpener (read our equipment review)

All About Manual Knife Sharpeners

How to Use: With manual sharpeners, the abrasives are either on nonmotorized wheels or the abrasive material itself is fashioned into a V-shaped chamber through which the user pulls the knife. In general, pull the blade through the chamber with even pressure. Always follow the manufacturer's instructions.


  • Tall walls hold the knife steady so that the user can draw the blade through the chamber with even pressure.
  • The slim body easily stows in a drawer, making it more convenient for routine upkeep.
  • Very good and quick at sharpening most kitchen knives.
  • Able to sharpen blades that feature a full bolster.
  • Very inexpensive.


  • Even the best manual sharpener can’t repair extensive damage to a blade (like removing notches).

Our favorite manual knife sharpener: Chef'sChoice Pronto Manual Diamond Hone Asian Knife Sharpener (read our equipment review)

All About Whetstones


  • Extremely adaptable; because the cook holds the knife at a specified angle to match the blade (Western, hybrid gyutou, Japanese), a whetstone can be used to sharpen any knife.
  • Can sharpen knives with a full bolster.
  • Most stones feature a coarse and fine side, which determines the amount of sharpening at each pass.
  • Relatively inexpensive.


  • Takes practice to master; need to hold the knife at the correct angle to ensure a proper edge.
  • Can take time to restore a very dull blade.

How to Use a Whetstone

Step 1: Secure Stone on Countertop

Place rubberized shelf liner or damp paper towels under whetstone to make sure it stays in place (whetstone should be coarse side up).

Step 2: Sharpen First Side

Face knife away from you and place handle end on whetstone at the angle of your blade (typically 15-degree angle for Asian-style knives and 20-degree angle for Western-style knives). Place other hand in the middle of the flat side of the blade, keeping your fingers flat and away from the sharp edge. Draw blade down the stone in a wide, circular manner, holding the blade at a constant angle until the tip of the knife runs off the other edge. Repeat several times, depending on dullness of blade.

Step 3: Check Sharpness of First Side

To check if the first side is sharpened, carefully run your thumb perpendicular to the edge of the blade–when you can feel the burr from handle to tip, that side is sharp enough. (Safety tip: Do not run your finger parallel to the blade.)

Step 4: Sharpen Second Side

Switch knife over and repeat the sharpening process in the opposite direction.

Step 5: Repeat Technique on Fine Side

Turn whetstone over to fine side and repeat process on both sides of knife until blade is sharp.

How to Sharpen Serrated Knives

Use a manual knife sharpener. Though serrated-specific sharpeners do exist, we’ve found them to be disappointing. And electric sharpeners don’t do enough: Their spinning wheels sharpen merely the edges and tips of the serrations, not the valleys between these tips. But that doesn’t mean you need to send out your serrated knives to a professional. A manual sharpener can ride up and down the different serrations (pointed, scalloped, and saw toothed), sharpening not only the edges and tips, but the deep valleys too. Serrated edges don’t need to be sharpened nearly as often as smooth blades: their pointed teeth do most of the work while the edges endure less friction.

How to Sharpen a Santoku Knife

Since our three favorite santoku knives have a variety of blade angles on their cutting edges, we wondered whether our winning knife sharpener, the electric Chef'sChoice Trizor XV, could sharpen them all. Happily, we discovered that it can when we uniformly dulled and resharpened their edges, they were as good as new.

Note that for knives with an asymmetrical edge, such as our winning santoku from Misono (read our full review of santoku knives), the sharpener manual directs you to use only one side of the machine's paired slots at each stage or honing, confining the sharpening action to that single side of the knife. In the final polishing slot, pass the other side of the knife through once, just to finish it off smoothly.

Is it Possible to Over-Sharpen Your Knives?

In short, the answer is no. Don't believe these common sharpening myths:

MYTH: Electric sharpeners take off too much metal.

TRUTH: With the right brand of electric sharpener, there’s no need to worry about excessive metal loss. Electric sharpeners do take off a small amount of metal each time you grind your knife—especially if you are using a coarse-grind setting to sharpen an especially dull knife. But our favorite electric sharpeners have three options for sharpening: coarse, fine, and a nonmotorized steel. The fine slot is the one you will use most often just to polish up a barely dull knife. Because you will be maintaining the sharpness of your knife with the lightest of the sharpening options rather than giving it an intense regrinding with the coarse slot, you shouldn’t worry about metal loss.

MYTH: For that matter, honing steels can take off too much metal.

TRUTH: Again, with the right tool, metal loss is nothing to worry about. The three types of steels on the market—regular, fine, and polished cut—all accomplish the same task to a lesser or greater degree. The rough, filed lines of the regular-cut steel are best for home cooks who only occasionally steel the edge of a knife. For professional chefs and meat cutters who use their knives for hours on end (and steel them multiple times per day), the fine and polished cuts are a better choice, as constant contact with the rougher surface of a regular-cut steel could wear away their knives’ edges.

Degrees of Sharpness

The more acute the angle, the sharper the blade will feel. When manufacturers report that a knife has a 15- or 20-degree angle, they’re referring to the angle of the bevel—the slim strip on either side of the blade that narrows to form the cutting edge.

Knife Sharpening Kitchen Hack: Use a Coffee Mug

Need to sharpen a small knife, but don’t own a knife sharpener? If you find yourself with a dull knife but without a knife sharpener, you can use the unglazed bottom of a ceramic mug to sharpen small knives. Applying moderate pressure, hold the knife at a 15-degree angle and carefully draw the entire length of the blade across the rough surface.

How to Store Your Knives to Keep Them Sharp

Storing knives safely and securely can keep their blades sharper longer, and out of harm’s reach. We don’t recommend storing knives in a drawer; as knives are moved about they can nick each other—not to mention you, too.

Universal Knife Block

Keeping your knives in any knife block is a big step up from a kitchen drawer, but we’ve often found that our collected knives don’t always fit into the preformed slots. A universal knife block will hold any combination of knives in a very small space. Our favorite universal knife block: Design Trifecta 360 Knife Block (read our equipment review).

Magnetic Knife Strip

Hang a magnetic knife strip on the wall and you’ve freed up both counter and drawer space. The long strip will hold any length of knife, and keep them handily in sight. Our favorite magnetic knife strip: Messermeister 16.75-inch Bamboo Knife Magnet (read our equipment review).

Knife Guard

These individual covers completely and securely store the knife. Made of polypropolene, they are a good choice if you must keep your knives in a drawer. Our favorite knife guard: Victorinox 8- to 10-inch BladeSafe Knife Guard (read our equipment review).

Knife Sharpening Takeaways

  • Sharpen your knives regularly. Even the best knives will dull over time with regular use.
  • A sharp knife is a safe knife. It is crucial to keep knives sharp so that they cut through food with less slippage.
  • Using a sharp knife will make your food taste better. Get the thin slices or a fine dice you're looking for, not large or ragged hunks. Precisely cut food will cook at an even rate and produce a much more successful dish.