How to Measure a Knife Blade Length

You should measure from the tip of the blade to the point at which the handle starts. The correct way to measure knife length can differ between states within the US and also differs in some other countries. It is important to ensure that you are aware of any relevant local legislation.

What Length Should You Consider: Knife Blade’s Size

The American Knife and Tool Institute provides the following guidance for measuring a knife: “the measurement shall be the straight line extending from the tip of the blade to the forward-most aspect of the hilt or knife handle.”

Knife blades are measured in inches. In most states in the US, it is legal to carry a knife with a blade that is 2.5 inches or shorter. It is really important, though, to ensure that you understand the knife-carry laws in your state.

In most states in the US, short-blade pocket knives are legal. In general, the longer the blade of a knife (for example, more than 2 or 3 inches), the more likely it will be that a state will consider it illegal or restrict possession.

How to Measure the Length of a Knife Blade in 3 Steps

Measuring the blade of a knife can be tricky, but if you follow these 3 steps, you can ensure a reliable result no matter what type of knife you are measuring.

You will need:

  1. A measuring tape or ruler marked with inch increments
  2. A notepad and pen to record your measurements
  3. The knife you wish to measure

Step 1: Hold a Ruler From the Tip of the Knife

You can use a measuring tape for this step too. The measurement is taken from the tip of the knife blade to the heel of the knife. This is the point at which the handle begins. This method works for fixed-blade knives.

Pocket knives should be fully opened and then measured in the same way. Some knives, such as a chef knife, have what is called a bolster. This is an unsharpened exposed part of the knife which is usually narrower and indented.

With chef knives or any other knife that has a bolster, you will measure from the tip of the knife to the beginning of the heel section.

Step 2: Note Down the Readings

Make a note of the measurement by rounding it up to the closest whole eighth of an inch. Write it down on your notepad.

Step 3: Repeat for Accuracy

Repeat steps 1 and 2 for accuracy.

Why Should You Measure the Blade Length?

  • To ensure that we abide by the knife-carry regulations for our state or country. It is vital to ensure that you are fully informed about the country-specific regulations for the length of a knife blade that is legal to carry in the country or the state you live in.
  • To ensure that the knife is fit for purpose. Depending on what you are going to be doing with the knife, you need to ensure you have an appropriate length. You wouldn’t chop onions with a samurai sword, now would you?
  • To ensure that you will be able to handle the knife. Hand sizes and arm lengths all come into play here and to comfortably wield a knife, you need to understand its length.

Is the Legal Blade Length the Same as Cutting Edge Length?

No. The legal blade length is the length from the tip of the blade to the heel of the knife. The cutting edge is the sharpened area of the knife that will cut. For legal purposes, when answering this question, we disregard the cutting edge length and focus only on the total blade length.

How to Measure a Knife for a Sheath

If you are purchasing a knife to carry with you, it is vital to have a sheath to protect you from accidentally injuring yourself. A sheath also protects your blade from accidental damage.

A knife sheath should cover about three-quarters of the total length of the knife. The easiest way to ensure you get accurate measurements of your knife for a sheath is to lay the knife flat on a large piece of paper, and, using a pencil, trace around the knife. If you would like to, you can then measure the various points (length and width) of your knife and mark those measurements up on the piece of paper.

Don’t forget to measure the thickness of your knife at the widest point of the handle to ensure it fits into the sheath. This measurement process is, of course, only necessary if you cannot legally carry your knife to the store where you plan to buy your sheath or if you would like to make your own sheath.

Sheaths are most commonly constructed from leather or Kydex.

Are Knives Measured by Blade Length?

Yes. Knife size always refers to the length of the blade and disregards the length of the handle. The length is measured from the tip of the blade to the beginning of the bolster area.

When you are looking at purchasing knives, no matter whether they are for collection purposes or even if they are kitchen knives, the lengths you see in the product descriptions refer to the blade lengths.

Does Knife Length Include Handle?

No, the knife length does not include the handle. Knife length is measured from the tip of the blade to the foremost part of the handle.

What Is the Longest Knife You Can Carry in Canada?

In Canada, the intent with which you carry the knife is more important than its length. There are many weapons that are banned for public carry in Canada, but where knives are concerned, any knife that is less than 30 centimeters (about 11.8 inches) is legal as long as:

  • It is carried for use as a tool only. In other words, it cannot be carried for malicious purposes or even for self-defense (this is where intent comes in.)
  • It is not concealed. The knife must be carried on your person in such a way that anyone approaching you should be aware that you have a knife with you.

Automatic knives and so-called “credit-card” knives are banned in Canada.

Brian Casey
About Brian M. Casey

As a food lover, Brian M. Casey developed a fascination for cooking at an early age. He soon realized that not only the ingredients matter but also the knives and the accessories used to turn those ingredients into a delicious dish. This way, Brian began his journey on the magnificent world of kitchen knives, outdoor knives, knife accessories, and much more. After years of experience with many ups and downs, Brian now wants to share everything he’s learned during his journey as an avid knife collector, a well-seasoned knife maker, and an all-around knives enthusiast.

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