How accurate is a line level?

Mosey · Nov 22, 2002

I used a line level to see if I have my new pole barn site level. The fill dirt is 26' long and I had 10" of drop. I put the line level in the center of the string, which I had very tight. I also turned the line level around and it read the same each way. How accurate can I expect to get with a line level? Can I assume I'm within an inch either way in 26'?

gerard · Nov 22, 2002

Don't have a perfect answer for u but if you get it perfectly level (the bubble), then go to one side, move the attachment point up a few inches, then check the bubble to see if you can see a difference you should get a good idea of how "sensistive" it is to differences. You also could consider getting a lazer level ($20) which works well for short distances like you're dealing with, or use a liquid level which is the simplest and most accurate. (You can make your own - just get some garden hose connections, a couple of feet of clear plastic hose, attach a clear section to each end of a garden hose with a shut off valve on each end and you have a perfect liquid level that works over any distance as long as you have enough garden hose. A little food coloring in the water makes it easier to see the level from a distance)

Anonymous Poster · Nov 22, 2002

If the line level read the same when you flipped it end for end, and the string was tight, you should be within 1/4" over the distance you are using it on. The major error factor in a line level is the ability of the human eye to judge microscopic movement of the bubble.

dlabrie · Nov 22, 2002

I used a line level to level an area 30X40 for an above ground pool. After the pool was installed, I checked the level of the water from the top edge of the pool and it was right on.

Mosey · Nov 22, 2002

"within 1/4"" or "right on" - either way I should be in great shape! Thanks.

gmason · Nov 22, 2002

I would think if you have found the center of the string and it doesn't have to much slack yoiu'd be close.
anything to one side or the other though would be way off.
g

RanchMan · Nov 22, 2002

<font color=blue>or use a liquid level which is the simplest and most accurate</font color=blue>

I figure if it was good enough for the Romans on their engineering marvels, it should be adequate for my projects too. I just bought a big roll of clear tubing from Lowe's and a funnel so I could pour the H20 in to it. Not as fancy as the one you discuss, but it works great. I've used it many times for many things and never had a "bad calibration." Gravity is funny that way... /w3tcompact/icons/wink.gif

crb478 · Nov 22, 2002

The trick with a line level is to get the line absolutely tight, any give at all and it will show level in the center if the ends are within a few inches of level. Water levels are very accurate and cheap. lasers are great as long as you have something set up that will show the laser dot. I knew a older gentle man once who used to sight houses with a 55 gallon drum, two foot level and a 3 foot piece of 1/2" galvinized pipe. He would level the 55 gallon drum in two directions with the level and then put the pipe on top of the drum and sight through it to the different corners. He would guarantee it accurate to within 1/2 in in 100 foot. I personally never knew him to be off.

Anonymous Poster · Nov 22, 2002

Hi,

A poster above set the key consideration I think...

Check the line level in both directions...ie, reverse it.

If it reads the same both ways it is accurate and will read quite well over a distance of 30 feet or less.

You will never notice a 1/4 inch error over 30 feet...if you are a normal human...

Bill in Pgh, PA