How To Correctly Measure Your Lawn Mower Blades

If you're wondering whether you should sharpen or replace your lawn mower blades, ask yourself: When did you last replace them? Generally speaking, how often you need to replace them hinges on how frequently you mow, the conditions you mow in, and the condition of the blades themselves. This can happen roughly once a year. More than that, when you come to replace them, don't just go and buy a generic replacement. Unfortunately, lawn mower blades are not universal, and it's important to ensure you buy the right blade for your steed. The best way to do that is to refer to your manufacturer's instructions. But if they, ahem, "accidentally" got tossed into the trash just as soon as you pulled the mower out of the box, what then?

In that case, one way to choose the right lawn mower blade replacement is to measure your old one first. And it's actually very simple to do. First, you'll need to remove the blade from the mower to prevent the mower from starting accidentally while you're working on it. Then measure the length by running your tape diagonally along the blade, from the corner of one end to the opposite corner of the other — like you'd measure a TV. Next, measure the width of the blade at its widest part — usually near the central hole. Finally, you'll need to measure the hole itself. There may be just one central hole, or your blade may have smaller holes on either side. If the holes are round, you'll want to measure the diameter of each one. You should also measure the distance from the center of one side hole to the center of the other. As a final tip, to make your shopping that little bit easier, note down the measurements in both inches and millimeters, as some stores may list the specifications differently.

As well as noting your measurements as accurately as possible, there are some other things to bear in mind before you go ahead and order a new blade. The first is how many blades your mower uses (usually one or two), which will depend on the type of mower. This seems obvious, but we've included it because if you have, say, two blades on your mower, you'll want to replace them both at the same time to keep things balanced. If you don't, you could be left with one dull blade still in situ, which is one of the most common causes behind damaged lawns.

You should also note the types of holes your blade has. Round holes are common, but center holes can also be rectangular, star-shaped, or in a "bow-tie" pattern, among other designs. You can order a new mower blade in the right length, but if the hole types and dimensions don't match, it simply won't fit your lawn mower. You should also double-check whether your blades are designed for left-hand (counterclockwise) or right-hand (clockwise) cutting. Many mower blades rotate clockwise, but this is far from universal. Get it wrong, and the blade won't cut as intended.