# How you measure the slope with a 48 inch digital measure?

Yes, I looked at the question:

How do you determine the slope of a floor?

I'm trying to measure the slope of the bedroom. I know that the bedroom is sloped, but I am hard time finding out by how much. So I got one of these: https://www.homedepot.com/p/Empire-48-in-True-Blue-Digital-Box-Level-e105-48H/306839434

Only in 6 different places on the floor(which are in horizontal straight line), when I place the Box level vertically, it shows me a slope of 1/8 / ft in the digital box. I don't know what this means, can someone please explain how to measure the slope of the floor?

Someone below asked me what is unclear in the 1/8th per foot. I'm trying to gauge how do I extrapolate it to 8ft. But I'm unable to, since the slope is zero if I move my measure in a straight line.

• presumably that means it drops 1/8th of an inch rise for every foot of run. Commented Jan 25, 2021 at 23:55
• Did you read the instructions that came with the device? There are some standard terminologies used in the construction industry, but the only way to know for sure what the display on the device means, is to look at the documentation for the device. Commented Jan 26, 2021 at 0:19
• If the floor isn't 100% flat, then you can't extrapolate the slant/slope at any given point to the whole floor. Maybe you need to take a step back and figure out why you think you need to know the slope. What are you actually trying to do here? Commented Jan 26, 2021 at 3:37
• Frankly, if you've only got a 1/8" deflection in the floor level here and there, you've got a very flat floor! I presume that you've got a wooden floor (joists, subfloor, floor, covering), not a poured concrete slab. Wood moves and it probably wasn't perfectly flat the day it was built, either. BTW- this is a perfect example of an XY Problem you're asking how to check for level, when your real question is "should I call in a structural engineer to check my house". That is the question you should be asking, and you should be providing (con't) Commented Jan 26, 2021 at 13:31
• reasons you think you need to call one in to look at the place. Are there cracks in walls or ceiling? Are there noticeable dips or rises in the floor or ceiling? What is it that prompted you to do all this detailed checking in a relatively new home that (presumably) just passed a pre-purchase home inspection? Commented Jan 26, 2021 at 13:33

If it's a cruddy level it may be different when reversed. I have one level that is off by about 1/8 over it's length this way. E.g. if it's level one way, reversing it takes a 1/8" rise on one end to fix. I use this one or rough work, and for drawing lines on plywood.

Ok the level works. You need a longer level. Go buy the longest straight 2x4 or 2x6 you can that will fit in the room. Look down the length of it, or better, run a tight string down it to see that it's straight. Piggy back your level on this.

A far easier way however is to get a self leveling laser level.Set it up so that it's exactly X inches above the floor at some point. Now with a tape you can run around and map out your floor. Mine has a couple of gratings that can be put in the path. One spreads the beam into about a 45" wide beam. Set up in one corner and do most of the floor with 2 moves. (The other makes it spread vertically giving you a perfect plumb line.

Does the slope indication change sign if you reverse the level?

Does the readout change to level, or 1/4" per foot if you place a 1/2" block under one end of the level? Does it change to the other one of these if you change which end the block is at?

If so, you seem to have 1/8" per foot slope. so, in a distance of 4 feet, there is a difference from level of 1/2" (or 4/8")

If you like other fractions, in 96 (units) the floor differs from level by one (unit). Or you could call it 1.04% - same thing.

• > Does the slope indication change sign if you reverse the level? Yes, it does. > Does the readout change to level, or 1/4" per foot if you place a 1/2" block under one end of the level? Does it change to the other one of these if you change which end the block is at? Yes, it does. Got it, thank you! But a bigger question is, if I move to next 4 ft, the reading shows zero. So does that mean it in a distance of 8ft, it is (1/2 + 0)/2 which is 1/4. Thank you! Commented Jan 26, 2021 at 3:33
• @abhididdigi, no, it means that there's a slight slope in one area, then there's a level spot at that new elevation. Commented Jan 26, 2021 at 13:34