How Often Should You Replace Your Lawn Mower Blades?

A lawn mower can feel like one of the most powerful tools you own. It's a whirling, gas-powered (or battery-powered, depending on your needs) dynamo of grass-chopping muscle. However, just like any other tool, even a lawn mower can be worn down by the ravages of work and the passage of time. Those mighty spinning blades get the worst of it, gradually dulling and chipping until they stop cutting grass and start slapping it.

The only course of action when your lawn mower blades start to wear out is to remove and replace them with a fresh set, ready to resume chopping. The question, then, is when exactly are you supposed to replace the blades? Assuming you make proper use of your lawn mower on a semiregular basis, you could generally get away with replacing the blades once per year, possibly longer than that if you're not using it very often. However, the time your blades last will depend largely on what you're subjecting them to, and it's on you to monitor for signs of early degradation so you can replace them with ideal timing.

For the average homeowner using a lawn mower once every few days for regular lawn maintenance, a good set of mower blades will typically last you for about a year, possibly two years if you're using it with reduced frequency. By the time a year passes, your mower blades will likely have reached a state of dullness on their own that necessitates a swap-out. If you take the effort to individually sharpen and care for your blades after every use with tools like a file or angle grinder, you could theoretically make them last as long as three years, but this is assuming the best possible conditions and only regular usage.

The tricky thing is that your mower blades' lifespan will depend largely on what they've endured in their lifespan. If all they were doing was cutting grass, they'll last a good while, but grass is rarely the only thing a lawn mower encounters. Impacts from small rocks or bits of pavement can dull, dent, and chip your blades, and even certain types of longer, thicker grass will wear them out faster.

Rather than only replacing your blades annually, keep an eye and ear out for the warning signs that your blades are on their last legs. This can include obvious chips and blunting in the blades, strange noises or heavy vibration while the mower is in use, and uneven, frayed cuts on grass you move the mower over. If these signs start to accumulate, it might be time to replace those blades, even if it hasn't been a year yet.