How Fast Does A Weed Eater Spin?

weed eater spin

You’ve probably wondered: how fast does a weed eater spin? You know the best weed eaters can put out some high torque, but just how fast are they?

Are they as fast as propellers of indoor helicopters or as fast as a hurricane? In this post, we’ll look at some facts about weed eaters to try and figure out how fast they spin.

How Does a Weed Eater Work?

A weed eater, also known as a string trimmer, is a gardening tool used to cut back overgrown grasses and long weeds in places a lawn owner finds hard to reach.

Homeowners use weed eaters around lawn edges and behind flower beds, typically places that are hard to reach.

There are gas-powered weed eaters and electric weed eaters. A gas string trimmer has more power. A cordless weed eater is lightweight, has easier handling, and doesn’t require constant maintenance.

Power notwithstanding, a weed eater features a string wire that spins at high speeds, enabling it to cut through grass or weeds quickly.

How Fast Does a Weed Eater Spin?

The speed of your weed eater will largely depend on the model. Various factors affect the machines’ overall performance, such as the length of the string and the motor’s power.

When figuring out how fast a weed eater spins, you need to consider two things: the electric motor type and the motor size. The motor type determines how far the head spins, and the motor size determines the speed of the head.

The average rotation for a weed eater is around 7000rpm, but some models can be as slow as 3000rpm. You may even come across weed eaters with incredible speeds of up to 15000rpm.

You can calculate the speed of a weed eater by multiplying the number of revolutions per minute (RPM) for its crankshaft with the radius of its cutting head. The RPM is how many times the crankshaft makes a complete revolution in one minute. The radius of the cutting head is the distance from the center to the outer edge.

string trimmer head spinning FAST

Weed Eater Idle Speed vs. High Speed

You should also consider the speed of your model when it is in idle mode vs. when operating at full speed. Let’s go into more detail.

Idle Speed

How fast does a weed eater spin in idle mode? A weed eater in idle mode has an RPM of 2700–3000, but this differs by model. For instance, Husqvarna group weed eaters typically have a speed of 2800rpm when on idle mode.

High Speed

The RPM of gardening machines generally increases when you operate at higher speeds, so how fast does a weed eater spin at high speeds?

On average, the engine of a weed eater spins at 7000rpm at high speeds. Just like a mower, expect to see models with powerful motors that clock 15,000rpm.

When running at high speeds, most weed eaters have an RPM of up to 10,500.

Weed Eater String Matters

The speed of a weed eater largely depends on the string width and string length of the machine.

String Width

The speed of a weed eater is affected by string width, larger diameter strings spin faster than smaller diameter strings. The machine will spin faster when you have a long piece of string in the trimmer. You can get a higher RPM by using a shorter string or switching to a thinner string.

It takes more effort to start up a weed eater with a large string, resulting in lower gas mileage. Use the largest diameter and shortest string length recommended for your weed eater model.

String Length

The answer to the question “how fast does a weed eater spin” also depends on the mower’s string length. Weed eater string comes in a variety of lengths.

Shorter strings can spin at higher speeds than longer strings because they require less energy to operate. Use a shorter string if you want your weed eater to spin faster.

The debate on the ideal string length in a weed eater is not just open to opinion, but it happens to be one of the most controversial topics. So, how long should a string be?

There are some factors you need to consider when figuring out the optimal length of a weed eater:

  • Cutting tool: The cutting tool directly impacts the length of the string required. So, depending on whether you have a trimmer or a brush cutter, you might want to consider a shorter or longer string, respectively.
  • String thickness: The thickness of the string can impact its ideal length. So, if you have thick strings, use them in combination with longer ones and vice versa.
  • Cutting speed: The speed at which you cut will determine how often you will need to replace the string. If you’re moving fast, be ready to do replacements more often than someone moving slowly.
  • Agility: How agile is your weed eater? If agility is your main focus, then you’ll need shorter strings that can reach narrow spaces.

Gas String Trimmer RPM

A gas weed eater is more powerful compared to an electric model. Although some electric string trimmers can be pretty powerful, they still can’t compare to the power of a gas model.

Even so, it helps to consider the type of engine for your gas model. There are two types of engines: the 4-stroke and the 2-stroke.

2-Stroke vs. 4-Stroke

A gas-powered weed eater starts when the cord is pulled. Once pulled, the flywheel starts to send energy to the ignition, which will cause the spark plug to send off a spark, lighting the fuel and turning it to gas which makes the engine operate.

In a typical weed eater, the RPM for a 2-stroke engine is about 8,000 to 10,000 RPM depending on the manufacturer. The RPM for a 4-stroke engine in a typical weed eater is about 3,500 to 5,500 RPM depending on the manufacturer.

A 2-stroke engine has no valves and is lubricated by mixing oil with the fuel. They generally have more power than 4-stroke engines but are less efficient and produce more exhaust. They have higher emissions than 4-stroke engines, so they’re not recommended for use in city areas or inside because of the increased air pollution they produce.

A 4-stroke engine is more efficient, produces less exhaust, and is quieter than a 2-stroke engine, but it will take longer to start up than a 2-stroke engine because it’s not as easy to get running after being left off for a while (because it doesn’t have any valves).

Electric Weed Eater RPM

An electric weed eater comes with plenty of advantages. For instance, these models are designed to be lighter because their engines are also light in weight.

Both corded and cordless weed eaters are straightforward to use; with just a single push, you’ll be ready to go. Nonetheless, the drawback to these models is that they aren’t as powerful as the gas models.

Electric weed eaters have an average RPM of 6000 – 8500, which works well for most domestic garden applications. What’s more, you can adjust an electric weed eater to rotate at a speed that’s suitable for the foliage type you’re dealing with.

However, if you have the cordless model, remember that the higher the RPM, the faster the electric battery drain. That means longer wait times during charging. You won’t have to deal with downtimes with gas models since you can just refuel up and continue.

Should You Run a Weed Eater at Full Throttle All the Time?

The answer is no. Running your weed eater at full throttle will quickly wear down the engine and parts. An engine running at full throttle uses more gas and could overheat or break. In fact, running your weed eater at full throttle for an extended amount of time can cause it to explode in your hands! When possible, it’s much better to use the half throttle and only use full throttle on thick brush or heavy weeds.


How fast does a weed eater spin? Well, we now know that a weed whacker can spin at between 3000rpm and 15000rpm—conclusive proof that they are faster than a lawnmower. If you have any further questions on weed eater speed versus lawnmowers, please go ahead and leave a comment! 

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