# How to tell if surface is level

I'm renting a room and the floor is not very even. I plan on wedging some cardboard/cloth/felt sticky pads beneath some surfaces (such as my chair and bed).

The first step is to test in which direction the object is lowest. I don't own a level. I've heard of putting a marble on the surface and seeing which direction it rolls, but I don't have any marbles either.

UPDATE: I was about to say I didn't have any wood, but there's some houses being built close to me and the workers said I could take a plank.

I'll give you two options for making a level of your own. Both are based on the simple fact that water is level, and will keep being level even going through a hose.

## Level based on glass of water

The most rudimentary level you can have is a single container of water, and just watch the level of the water. This can be a glass bowl, or as simple as a single glass. If you combine this with a straight piece of wood, you have a rudimentary level.

This can give you an accuracy of centimeters or parts of an inch, if used carefully. And the combination of a 3' / 1m piece of wood and glass, can be used together to measure if different furniture are reasonably level. You could even use the water glass / glass bowl directly on the furniture to verify that it is reasonably level.

Added: A variation of this, requiring a little balance act, is to use two glasses one at each end of the plank. And then you can visually align this to get a sense on how unlevel it is.

## Level based on bottles and a hose

A much better level requires a little more equipment: two clear bottles, a hose and some tape to join it all together. The base setup is like in the image below:

To make this you cut off the bottom of the two bottles, and join them to the hose using tape. Fill up from one end until you have water appearing in both of the bottles.

This arrangement will have the water stabilising at the same level. If you have a few friends helping you, you can measure distance from the water level to your floor and decide what is level.

Another option using this level is to use it close to the wall, and mark on the wall (i.e. using tape which can be removed afterwards) where it is level, and then measure out the floor at different points.

Or you could use a tripod and fasten one bottle, measure the distance down to the floor, and then move the other bottle around and measure the difference of distance to the floor on different locations.

First of as Zaaikort indicates, you can also use a (semi-)transparent hose without the bottles as the level. In my experience though, it is a little easier with the bottles.

One way to 'calibrate' the system is that you attach one bottle (or that hose end) to a chair (or stick) and make a mark on the bottle at the water level. Hold the other bottle next to it and make the mark at the other bottle as well. Make a note of the length down to the floor from the water level.

When you now move the loose bottle around in the room, you can measure the distance from the water level and down to the floor. If it is not the same as the original distance (from the chair/stick) to the floor, you are not level and you can subtract the two values to see how much it is off.

• Thanks. How do you actually used the second method in the sense how do you play the bottles on a surface? Commented Sep 28, 2015 at 1:35
• @CeleritasThe bottles are not essential, just a more-or-less transparent hose will do the job. You could tape each end to a vertically held stick touching the floor. To calibrate the tool, first place the two sticks together on the same spot and mark the water level on each one. Commented Sep 28, 2015 at 8:35
• @Celeritas You don't set the bottles on the surface of anything. This method is best when you want to check the level of something that's very long, longer than a traditional level might help with. I used the bottle-less method in the past to make sure a drop ceiling I was installing was level across the length of the room. It required 2 people, but with one holding each end, we marked a line on the wall next to the water level at both ends at the height we wanted. From there a straight chalk line between the two marks gave us our level line across the length of the room. Commented Dec 10, 2015 at 20:32

Marbles are just one option. You can roll a basketball, soccer ball, racquetball, one of those 50-cent bouncy balls kids get from a vending machine, or any other ball. I recommend giving it a tap to start it rolling, and see which way it heads.

You can also use anything cylindrical that can roll. In elementary school I would roll a pencil one direction on my desk, and it would roll back the other way, so I knew it wasn't level. You can do that with a drinking glass that's shaped like a cylinder, rolling it different directions to find out if it stops and rolls back the other way. For example, roll it forward, then retrieve it. Staying in the same spot, turn a little to your right and roll the glass forward again. Repeat this until you've made a complete circle. If it rolls back to you at some point(s), it means the direction you're rolling it is higher than the spot you're rolling it from.

• I've used a nickel before Commented Sep 29, 2015 at 13:59

There are numerous smart phone apps that turn your smart phone into a level. Many are very accurate and free. If you have a smart phone, search the app store for 'level' or 'bubble level'.

• how do you know they are accurate? Commented Sep 30, 2015 at 22:29
• @chicks - I think you need to calibrate it first - on a known level surface. Then it knows how unlevel another surface is by the gyroscopic reading differences. So, what surfaces to you know are level?! Commented Oct 1, 2015 at 20:22
• But this doesn't tell you the accuracy I suppose. Each phone manufacturer may use different hardware, so each device may vary. Testing over time will tell you (especially paired with a real level!). Commented Oct 1, 2015 at 20:34
• What surfaces do you know are level? Water. Put some water in a frying pan, a paper plate on the surface, and calibrate the phone whilst it rests on the floating plate. Be careful, and maybe try other things than frying pan or paper plate. I only say paper plate because there probably isn't too much height variation of that surface.
– Carl
Commented Oct 2, 2015 at 20:13