The online comic Xkcd.com has a series called “What If?” where readers write questions and they’re answered as comics. The Constant Groundskeeper gave me the motivation to do my own version of the question: How big of a lawn could 1 person with 1 push mower keep mowed at a perfect height?
Here’s how I worked it out:
The average walking speed is 5km/hour or 3.1 miles/hour. And if we’re using a typical 19-inch push mower we can mow 1 acre in 101 minutes.
Grass Growing Speed
Estimated grass growth rate is 2 – 6 inches per month depending on grass type, rainfall, sun exposure etc. Let’s assume our grass grows 6 inches per month.
Keeping the Lawn the Perfect Length
First off I wanted to say: I’m going to forget about working hours and just calculate the lawn size based on a person mowing for 24 hours per day.
I like short lawn so we’ll keep our lawn at 3 inches. It needs to be mowed every 1 week since ideally you’re supposed to only take 1/3 the grass length off with each mow. So every 7 days. Every 168 hours. Every 10,080 minutes.
So if we had a lawn that was 99.8 acres by the time our mower returned to the start the grass would be ready to cut again.
What Famous Things Could You Keep Mowed?
99.8 acres is:
- About 1.5x USA’s biggest shopping mall – King of Prussia Mall. If it had no walls and was all grass you could have 1 groundskeeper on staff and he’d only have to work about 15.5 hours per day every day to keep it perfectly mowed.
- Smaller by 1.6x than Disneyland. If Disneyland grounds was all grass instead of concrete 1.6 groundskeepers could keep the whole thing perfect if they mowed 24 hours per day and never took a break.
- About 8x smaller than Central Park. 8 of our 24-hour-per-day-no-break groundkeepers could keep all of Central Park perfectly mowed if it was nothing but grass lawn.
- About 58 soccer fields.
1. Tom Voigt wrote an extensive piece on mowing and the recommendations of mowing height to keep the healthiest grass lawn.
2. Wikipedia pages used to find out famous things areas: Biggest malls, soccer field size, Disneyland area and Central Park area.
Here you’ll be able to compare the time it takes for different mowers to mow 1-acre of lawn.
I was curious how long it would take to mow 1 acre (76% of an american football field) with the different types of lawn mowers – push and riding. So I did the math.
Here’s the results (making the assumptions listed below):
Do these numbers seem really fast? I thought so too. 8.5 minutes to mow 1 acre with a zero turn mower? I don’t think so. But it is correct for my perfect world scenario… The lawn is flat, free of obstacles and preferably 1 long lane the same size as the mower cutting width so you just drive forward as fast as possible.
At home, at your lawn you will probably need to move around obstacles, go up some slopes, turn directions often, speed up slow down etc so the numbers above are simply representative of how much faster one is compared to the other.
The table below displays the numbers used to calculate the 1 acre mow time. See below the table for specifics.
|Mower||Type||Mph||Ft/min||Width (ft)||Acre (mins)|
1 acre = 208.71 ft x 208.71 ft
1 mph = 88 feet per minute
- Divide the 1 acre area into lanes. One lane is equal to the width of the mower deck/cut width times the length of the 1 acre square (208.71 ft).
- Multiply the mow speed (speed of walking for the push, or declared max speed for the riding mowers) in mph by 88 to get the speed in feet per minute.
- Now you can find out how many lanes you can mow in 1 minute. And how many lanes are in the 1 acre square.
- Divide the lanes in the acre by the lanes you can mow per minute and you have the minutes to mow 1 acre.
- Lawn is a perfect square with no obstacles.
- The mowing lanes have no overlap and are exactly the size of the mower cutting width.
- Riding mowers go at max rated speed.
- Push mower goes at average walking speed.
- Turn around times after each lane are negligible.
In Germany, they call videos like this efficiency-porn.
Watch the video then read the text below.
That lawn mower is awesome, yeah?
And although what it accomplishes is amazing – it doesn’t compete with the lawn mower in the next video.
And back on planet Earth – the best lawn mowers look like these.