How to Test Knife Sharpness

Did you know that a dull knife is much more dangerous than a sharp knife? Maintaining the kitchen knives adequately, doing sharpness tests, and taking proper care will prolong their life. If you want to learn how to test knife sharpness, the five tests below are simple and will take you only minutes to do.

Easy Sharpness Tests

Sharpening a knife is an essential part of maintenance, whether it’s ceramic or stainless steel. These five tests can be your go-to whenever you’re not sure if you need to take action.

  1. Visual Inspection Test

Visual inspection is the most basic test that will give you a lot of information about the sharpness of the edge of your knife. All you need to do is take a look at the blade using a flashlight or your phone’s flashlight to see if it looks dull and if there are any irregularities. The sharper the blade, the thinner it will be, and you shouldn’t actually be able to see it as a surface. Seeing the light reflecting from the edge of the blade means it’s already dull and needs to be sharpened.

  1. Paper Test

Paper TestSlicing paper is another knife sharpness test you can try at home. You will need a piece of paper and a knife. If your knife can cut through the paper with ease, your job here is done. But, if it only tears it, then you need to sharpen it. If you want to take things up a notch, find a magazine and perform the paper test on it.

  1. Tomato Test

Tomato TestThe tomato test is one that you’ve seen on countless knife commercials and cooking shows. When a brand wants to show that their knives are amazing, they do this test. It’s actually a great one that will help you determine if your knife needs sharpening.

The riper the tomato, the harder it will be for the knife to cut it. Because this fruit has skin and a soft inner part, the knife needs to be quite sharp to go through both parts.

Grab a tomato from your fridge, and place it on a cutting board. Start slicing it with the knife, only moving the knife horizontally without too much pressure. The mission is a success if the edge of your knife is sharp enough to cut the tomato without squishing it, and you don’t need to apply too much pressure to cut it.

  1. Hair Whittling Test

If you’re a real pro, and you want to test your knives, this is the ultimate test. Only a very sharpened knife will be able to pass this one.

To perform the test, you only need your knife and hair. It’s best if the hair is long because short hair is not as suitable and will make the whole testing process much harder.

Once you have the two essential items, start whittling the hair with the knife. Make sure that you use a gentle touch, otherwise you’ll cut the hair immediately. You should aim to split it and determine the level of sharpness of the knife. If it passes this test, it means that the knife is sharp enough to shave with.

  1. Finger Nail Test

For this test, you should place your finger on the blade and slowly move the fingernail towards the edge. Sharp edges can cut through a fingernail without you putting pressure. The test will be successful if you see a dent on your fingernail where it got in touch with the blade.


How to test if a knife is sharp? Well, there are several simple tests you can try at home. A sharp knife can cut through paper with ease and won’t appear dull or damaged on inspection. It will also be able to cut through a tomato without squishing it. A sharp knife will effortlessly leave a dent in your fingernail. Finally, the hardest test of them all is the hair whittling test. When the knife can whittle your hair, it doesn’t need any sharpening.

If you don’t have the time to do these tests, and you hate sharpening knives, you can simply buy a self-sharpening set of knives and call it a day!

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