What are some methods for figuring out the slope of a floor?

I've always heard the slope referenced as, eg: "1/2inch over 6ft." - is this the normal way, and/or are there other common ways to say it?

  • 1
    The level of your floor is actually a binary concept. It's either level, or it's "rustic and charming with its own unique quirks" ;o)
    – DA01
    Commented Oct 11, 2011 at 20:00
  • 1
    Yes, that's the normal way. You could also talk about the angle of the floor, but "half inch over six feet" is more descriptive for most people than 4.77 degrees. Commented Oct 13, 2011 at 15:40

3 Answers 3


One way is to take a long level (the longer the better : 6 and 8' levels work well).

Hold one end of the level on the higher point, and then once the level is level, measure the gap between the other end and the floor using a measuring tape. This will give you your height over your run (length of level), for that particular spot in the floor anyways.


Wow, a 1/2 inch over 6 inches is quite the floor, sure it is not a roof?!?! lol. I have never heard of a standard expression for floor level. I would simply express it over the span of the entire floor or from the crown spot. Example, 1 inch over 12 feet across joists, or maybe 1/2 inch over 8 feet with joists.

You are right saying that a long level can be used to measure the slope, however a laser is very useful in seeing all irregularities over the entire floor, side to side or any high spots in the field. Set the laser at maybe 6 inches above the floor as a nul reference, then take several measurement with a tape at several locations by setting the "0" on the floor and note where the laser hits the tape. Good Luck

  • he said " over 6' " not ' over 6" ' (but the quotes around the whole thing muddies it) ... it might've been a 1:144 slope if that first measurement was 1/2 an inch
    – Joe
    Commented Oct 4, 2011 at 12:01

The slope of the floor can be find by using two methods. One is by using slope formula and the other, by digital inclinometer. I think that mostly the floor slope is within 1-2% . Thank you. Best Regards, MKNMK

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