Knives in the Dishwasher: Why You Shouldn't and What to Do Instead

No, you should not put kitchen knives in the dishwasher. This applies to chef's knives, santokus, paring knives, and most other kitchen blades, even ones labeled "dishwasher safe." The combination of high heat, prolonged moisture, aggressive detergent, and the blades knocking around against other utensils will dull the edge faster than almost anything else. Do it regularly, and a knife that started sharp will need sharpening after just a few months.

That said, not all knives are equally sensitive to the dishwasher. This guide explains exactly what the dishwasher does to knife edges and handles, which types of knives are more or less tolerant, and how to hand-wash knives properly in about 30 seconds.

What the Dishwasher Actually Does to Your Knives

Most people assume the dishwasher is fine because the knife looks the same coming out as it did going in. The damage is microscopic at first.

The Detergent Issue

Dishwasher detergent is highly alkaline and abrasive. The grit and chemical compounds in the detergent attack the steel surface, particularly on high-carbon blades. Over repeated cycles, you get micro-pitting on the cutting edge and along the spine, which accelerates corrosion and oxidation. On stainless steel this happens more slowly, but it still happens.

Heat and Humidity

The wash cycle reaches temperatures of 140-160°F. The drying cycle can go even higher. This repeated heating and cooling causes the steel to expand and contract, which gradually weakens the temper of the steel near the edge. Over time, the edge becomes softer and dulls faster.

High humidity during the wash cycle and steam during drying also accelerates oxidation, especially on carbon steel knives and on any areas where the coating has been compromised. Even stainless steel can develop surface rust spots after repeated dishwasher cycles.

Physical Impact

Knives bounce around in the dishwasher basket. Every time the spray arm sends a jet of hot water around the chamber, utensils shift. Metal-on-metal contact chips and rolls the edge. This is one of the fastest ways to wreck an edge on a high-hardness Japanese knife, since harder steel is more brittle and more prone to micro-chipping than softer German-style blades.

Handle Damage

Wooden handles are particularly vulnerable. Repeated soaking in water causes wood to expand and contract, eventually cracking, splitting, or loosening from the rivets. Even sealed wooden handles can't hold up to dishwasher cycles indefinitely.

Synthetic handles (polymer, G10, Pakkawood) are generally more water-resistant, but the adhesives and rivets used in full-tang construction can still weaken over time with repeated soaking.

Which Knives Are More Dishwasher-Tolerant

If you absolutely must machine-wash certain knives, budget stainless blades with synthetic handles are the most tolerant. A $12 knife with a soft steel (52-54 HRC), a polymer handle, and no special coating can survive occasional dishwasher cycles better than a $200 Japanese knife with a 63 HRC edge and a walnut handle.

Even then, "tolerant" just means the damage is slower, not that there's no damage.

Knives you should never put in the dishwasher under any circumstances:

  • High-carbon steel knives (they rust aggressively)
  • Japanese knives with hardness above 60 HRC (edge chips easily)
  • Knives with wooden handles (cracking, loosening)
  • Knives with Damascus or etched patterns (detergent strips the finish)
  • Any knife with a high-polish edge (the abrasive detergent scratches the polish)

The best dishwasher safe knife set options are designed with thicker blades, corrosion-resistant steel alloys, and fully synthetic handles. If you want a set you can machine-wash without guilt, look for sets marketed explicitly for dishwasher use, where the steel and handle materials have been chosen accordingly.

How to Hand-Wash a Knife Properly

Hand-washing a knife takes about 30 seconds. Here's how to do it safely.

Step 1: Wash Immediately After Use

Don't leave a knife sitting in a sink full of soapy water. Soaking causes the same moisture damage as the dishwasher, just more slowly. Wash each knife as soon as you're done with it, or at least before moving on to the next task.

Step 2: Use Warm Water and Mild Soap

You don't need hot water or heavy-duty detergent. A drop of dish soap and warm water is plenty. Aggressive scrubbing pads are unnecessary and can scratch the blade surface.

Step 3: Hold the Spine, Not the Edge

Grip the blade with the spine (the blunt top edge) toward your palm and the cutting edge away from you. Wipe from heel to tip with a soft cloth or sponge. Never wipe across the edge, always along it, spine to edge.

Step 4: Rinse and Dry Immediately

Rinse thoroughly and dry right away with a clean towel. Don't leave knives in a drying rack to air-dry, especially carbon steel knives, which can develop rust spots within hours.

Steak Knives

Best dishwasher safe steak knives are one category where dishwasher tolerance genuinely matters, since steak knives go through heavy use during meals and people want convenience. Look for serrated stainless blades with polymer handles if you plan to machine-wash. Straight-edge steak knives will lose their edge faster in the dishwasher regardless of steel quality.

Storage After Washing

Dry knives should go directly to their storage spot, never tossed loose into a drawer. The edge contacts other metal utensils and dulls between uses. Options:

  • Magnetic strip: Keeps blades accessible and protected, zero edge contact
  • Knife block: Slide in spine-first to avoid running the edge against the wood
  • Blade guards: Snap-on plastic guards for drawer storage

FAQ

My knife says "dishwasher safe" on the box. Is it actually fine? "Dishwasher safe" usually means the handle won't warp or fall apart, not that the edge will be unaffected. You'll still experience faster dulling and potentially some surface oxidation over time. For a cheap knife you plan to replace regularly, occasional dishwasher use isn't a big deal. For a quality knife you want to last a decade, hand-wash it.

Can I put steak knives in the dishwasher? Serrated steak knives with synthetic handles are the most dishwasher-tolerant category of kitchen knives. The serrations don't dull as quickly from physical contact because the points are somewhat self-protecting. Still, frequent dishwasher cycles will eventually degrade the serrations and the handle. For quality steak knives, hand-washing extends their life significantly.

My knife has rust spots from the dishwasher. Can I fix it? Light surface rust on stainless steel can often be removed with a paste of baking soda and water, or a specialized rust eraser. Rub gently along the blade direction, not across it. For deeper pitting, a fine Scotch-Brite pad can remove the rust but will affect the finish. Carbon steel with significant rust may need to be re-seasoned with a light coat of food-safe mineral oil after cleaning.

Does the type of detergent matter? Yes. Pods and powder detergents with bleach or chlorine compounds are the most aggressive on knife steel. Standard liquid dish soap used in hand-washing is much milder. If you ever use a knife-washing station, use the mildest detergent available.

Conclusion

Putting kitchen knives in the dishwasher is a habit worth breaking. The damage is gradual enough that most people don't notice it happening, but it adds up. A 30-second hand-wash and immediate drying keeps an edge sharp, prevents rust, and protects the handle. If you're building or upgrading a knife set and dishwasher convenience genuinely matters to your household, choose a set built for it with the right steel and handle materials. But for any knife you actually care about keeping sharp, the sink is always the better option.