# Is there an easy way to calculate a block's light level?

I'm trying to build a house out of ice, for no other reason than sheer novelty. (Though perhaps also because I want to use my Silktouch I pickaxe)

Ice is a very finicky building material, prone to melting when exposed to the "normal" light levels of a torch. Specifically, if any adjacent block attains a light level of 12 from anything other than direct sunlight, it will melt.

And so, I reach a conundrum. I want to light my house enough so that I can see while walking through it, and also enough to completely prevent mobs from spawning inside my house. This means I want to keep the light level approximately between 8 and 11: easy enough to do someplaces, but a pain in the butt to calculate for every potential spawnable square.

Is there some way to identify the light level of a block without the tediousness of manually calculating each block's light level? I'd prefer an external tool over a mod, but I'm willing to consider the latter anyway.

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– ChrisF Oct 26 '11 at 21:59
@ChrisF the issue is not how to calculate light level. I know how to do that. The issue is needing to calculate the light level on each of the hundreds of square meters that compose my ice palace. – Raven Dreamer Oct 26 '11 at 22:06
I didn't realise the extent of the problem :) – ChrisF Oct 26 '11 at 22:06
Try turning off smooth lighting - it may be much easier to get a "feel" for how each light level looks like visually with the flat lighting view. – Random832 Oct 27 '11 at 16:26
I think you should try Red stone torches if not that then try glow stone. (glow stone is best) – user1015620 Oct 28 '11 at 21:26

Press F3, and look for the area labeled bl: When you find this it will tell you the artificial (not natural) light of the block you're standing on.

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awesome updated answer that deserves more upvotes – legacy Jun 26 '13 at 20:57
like benokt said the block lighting level will appear like this: bl:[light level] it will also appear by the biome display text like this: lc:[#] b:[biome] bl:[light level] 2nd to last line from the bottom – user52491 Jul 24 '13 at 15:19

Your best bet would be to open up your favorite skin, find the lighting file -- like this one -- and modify it in your favorite image editor so that the lighting levels above/below/inside your desired range are made obvious (red, green, and white may be good choices). Be sure to disable smooth lighting while you do this, though.

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Oooh, this looks promising. – Raven Dreamer Oct 29 '11 at 1:27
Hm. I can't seem to make this noticeable. I don't know if I'm just doing it wrong or what. – Raven Dreamer Oct 29 '11 at 2:36
Are you sure it's set up properly? If you make it something obvious like all red, then it should be pretty obvious if it's working or not. I'll take a look at it in a few hours and see if I can figure out the problem. – Xkeeper Oct 31 '11 at 23:33
if you get it working, see if you can upload it as a texture pack somwhere! – Raven Dreamer Oct 31 '11 at 23:39

Use the What's My Light Level? mod, compatible up to 1.9 pre-4 (unstable) and 1.8.1 (stable).

This mod provides an overlay that shows the light level of the block you are standing on.

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Neat! I'm trying to avoid mods though, because I'd like to build my ice palace on a multiplayer server. Still quite helpful for those building in single player, however. – Raven Dreamer Oct 26 '11 at 22:13
@RavenDreamer I think you may find that difficult (I'm not sure if there are any 'live updating' external programs, unlike mappers). My advice: build a small ice palacette in single player, until you've got the hang of where to put lights to prevent meltage, then go multiplayer when you've got enough practice. – fredley Oct 26 '11 at 22:16
Yeah, I wasn't looking for a live-updating program, just something that would let me iterate. Save map, view changes in external program, make changes as necessary, close map, reopen map,e tc. – Raven Dreamer Oct 26 '11 at 22:18
@Raven Dreamer — Not all mods require a server-side component. I've used Zombe's "safety" mod (another light-level indicator) in SMP on a vanilla server. I would imagine this one is SMP-compatible as well. – Ben Blank Oct 26 '11 at 22:49
Oh, wow, this was really easy to install. Nice. If Xkeeper can't get their texture pack idea working, I'll accept this. In the meantime... upvoats! – Raven Dreamer Nov 1 '11 at 1:58