# Lengths don't add up **URL:** \ **Category:** SketchUp Free\ **Created:** [January 5, 2021, 1:59am UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965 "2021-01-05T01:59:36Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![ptousig](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ptousig/32/109046_2.png) [@ptousig](https://forums.sketchup.com/u/ptousig)\ **Post date:** [January 5, 2021, 1:59am UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/1 "2021-01-05T01:59:36Z")
Frequently, when I assemble shapes together, the resulting dimensions don’t add up. Like the screenshot below. ![image](https://global.discourse-cdn.com/sketchup/original/3X/3/4/34afc81e642a23b1768e742a25954111e0beca58.png) Both rectangles are 1’3" long, but when next to each other, the total length is 1/16" longer than it should. I have zoomed in to the joint and it doesn’t show any gap. What I am doing wrong? ---
**Author:** ![endlessfix](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/endlessfix/32/148757_2.png) [@endlessfix](https://forums.sketchup.com/u/endlessfix)\ **Post date:** [January 5, 2021, 2:34am UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/2 "2021-01-05T02:34:07Z")
You are looking at rounded dimensions. Go to Model info (second from bottom on the right) and turn up the precision of displayed units. Sounds like it’s set to 1/16 which I believe is default. While you are there turn off length snapping. Are you typing in the size of those objects when you make them or dragging them out by hand? ---
**Author:** ![ptousig](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ptousig/32/109046_2.png) [@ptousig](https://forums.sketchup.com/u/ptousig)\ **Post date:** [January 5, 2021, 5:04am UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/3 "2021-01-05T05:04:09Z")
I usually type it in, but once in a while I drag. And sure enough, that was it. The rectangles were actually 1’ 3 1/64". Thanks! ---
**Author:** ![john\_mcclenahan](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/john_mcclenahan/32/135377_2.png) [@john\_mcclenahan](https://forums.sketchup.com/u/john_mcclenahan)\ **Post date:** [January 5, 2021, 3:00pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/4 "2021-01-05T15:00:57Z")
And yet they don’t show the preceding ~ (tilde) that SU uses to show that dimensions are approximate. Thanks to Steve (@slbaumgartner) for pointing out in a recent post that if dimensions are in feet, inches and optionally, fractions, the ‘approximate’ tilde is not shown. Bug? Odd design decision? Who knows. I certainly didn’t, before Steve pointed it out. If you changed your units to Fractional (just inches and fractions, no feet) do you see the ~ showing on at least one of your dimensions? ---
**Author:** ![ptousig](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ptousig/32/109046_2.png) [@ptousig](https://forums.sketchup.com/u/ptousig)\ **Post date:** [January 5, 2021, 3:27pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/5 "2021-01-05T15:27:20Z")
I do see the ~ (tilde) on other dimensions sometimes, but not in this case. I don’t know the logic that determines when it is shown or not. Switching to inches and fractions did not make the tilde appear. ---
**Author:** ![ptousig](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ptousig/32/109046_2.png) [@ptousig](https://forums.sketchup.com/u/ptousig)\ **Post date:** [January 5, 2021, 8:12pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/6 "2021-01-05T20:12:47Z")
Seems like the mystery is not quite solved. Even with the precision set to 1/64" some measurements don’t add up. ![image](https://global.discourse-cdn.com/sketchup/original/3X/7/b/7bf509c68431c3f0115aee6da6bbce41078bedf4.png) In this case, the distance between two points is 3’5" but if I pick a point between them and measure the distance on either side, I lose 1/64" somewhere. It’s not the end of the world or anything, but aren’t computers supposed to be good at math? 🙂 ---
**Author:** ![RLGL](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/rlgl/32/44295_2.png) [@RLGL](https://forums.sketchup.com/u/RLGL)\ **Post date:** [January 5, 2021, 8:43pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/7 "2021-01-05T20:43:28Z")
Post the model shown in the last reply so we can check it to see what is happening. As an exercise I used your 3’5" dim and placed an arbitrary point to dimension to. No matter how I measured the numbers added up. ---
**Author:** ![ptousig](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ptousig/32/109046_2.png) [@ptousig](https://forums.sketchup.com/u/ptousig)\ **Post date:** [January 5, 2021, 8:47pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/8 "2021-01-05T20:47:47Z")
Here it is. [Length Bug.skp](https://forums.sketchup.com/uploads/short-url/lyg50zd4Pu8xBQeBsWemQ7GFNkv.skp) (1.3 MB) ---
**Author:** ![brianmowrey](https://avatars.discourse-cdn.com/v4/letter/b/258eb7/32.png) [@brianmowrey](https://forums.sketchup.com/u/brianmowrey)\ **Post date:** [January 5, 2021, 9:04pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/9 "2021-01-05T21:04:43Z")
All three dimensioned distances are not exactly to 1/16" and are being clandestinely rounded. ---
**Author:** ![ptousig](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ptousig/32/109046_2.png) [@ptousig](https://forums.sketchup.com/u/ptousig)\ **Post date:** [January 5, 2021, 9:04pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/10 "2021-01-05T21:04:58Z")
I switched the units to “decimal inches” and now I see my measurements are off by small fractions. My 3’5" is actually 40.996277". Now, two questions: 1. Should there be tildes in front of those numbers? 2. Assuming I got this length by dragging; and I do have length snapping on. Shouldn’t the length have snapped to the nearest 1/64" fraction? While I was typing those questions, I noticed something else looking odd… My “snap interval” is set to 0.062520". Is that normal? That’s a tiny bit more than 1/16". Shouldn’t it be 0.0625" ? Did I accidently change that snap interval? ---
**Author:** ![Anssi](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/anssi/32/105_2.png) [@Anssi](https://forums.sketchup.com/u/Anssi)\ **Post date:** [January 5, 2021, 9:46pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/11 "2021-01-05T21:46:39Z")
It is best to stop worrying about the snap interval and turn off Length Snapping altogether. As a feature it is completely useless. ---
**Author:** ![system](https://global.discourse-cdn.com/sketchup/original/3X/f/2/f2a121500b085ed60806607a82720b092d800bb3.png) [@system](https://forums.sketchup.com/u/system)\ **Post date:** [April 7, 2021, 1:46pm UTC](https://forums.sketchup.com/t/lengths-dont-add-up/147965/12 "2021-04-07T13:46:40Z")
Closed on April 7, 2021, 1:46pm UTC This topic was automatically closed 91 days after the last reply. New replies are no longer allowed.