Answer: If you just want to know what height your mower is cutting at, you can measure from the bottom of the wheels up to the blade, or you can measure the height of your grass after you mow a strip.
Different mowers will have different ways of being adjusted for mowing height. On some you have to remove all of the wheels to do it, some more expensive mowers have a quick adjustment mechanism, and others have a lever to adjust at each wheel. Some mowers have as many as five height selections, most have fewer than that. I would suggest you look at your owners manual or contact the manufacturer of your mower for more detailed instructions.
I hope this helps.
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