# what does "is off by" mean in this context?

what does "is off by" mean in this sentence?

If the height of a single step is off by as little as two millimeters...

• off means inaccurate (as with a measurement) or not conforming to dimensional specifications (as with a manufactured object).
– TimR
Commented Mar 16, 2017 at 21:45

| be off by| means to be less or more than what a measurement should be. Any measurement: time, distance, height, width, weight, etc.

The wall measures 6 feet 2 inches, so the wallpaper has to measure the same thing. If the wallpaper is only 6 feet, it is off by 2 inches.

The man ran a mile in five minutes. [less] You're off by three. [in other words you ran it in eight]. [more]

Your ideal weight as a man should be 85 kilos for your height. But you only weigh 80 kilos. You are off by five. [less]

The time is 6 o'clock according to your watch. Mine is off by two hours. [Context will tell if it is supposed to 8 or 4 o'clock.] [travel and time zones]

• What's the opposite of "off by" in this context? Commented Apr 17, 2019 at 10:53
• @Kumarsadhu There is no opposite of "to be off by x" in this context. The idea of off relates to a measurement of some kind (time, distance, weight, etc.) and can be more than or less than some amount depending on the context. Only context will tell which it is. Commented Apr 17, 2019 at 14:41
• I got it, sir. Thank you. Commented Apr 17, 2019 at 14:45
• @Kumarsadhu Thank you for your question. I'm a woman but there's no need to say Ma'am. :) Commented Apr 17, 2019 at 14:48
• @Kumarsadhu It depends on your "standard". It does not mean an increase/decrease per se. If your standard rate is 1,000 rupees per widget, then 1,250 or 750 would be off by 250, up or down. If the standard time for a machine cycle is 25 minutes, and it only runs 20 minutes or 30 minutes, it is off by 5 minutes. The amount something is off, up or down, is in relation to some standard measurement implied or given in a context. Commented Apr 17, 2019 at 15:16

"is off by" means "is wrong or inconsistent by this amount". We normally expect stairs to all be the same size. If you are walking up a flight of stairs and one is a little different from the others, this can be very disconcerting. So they're saying that one step is a slightly different height than other steps.

We routinely talk about a measurement being "off by" some amount. Like, "When you set the flux on the hyperdrive, if you're off by more than 5% the engines may explode."