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Apologies if this question is too much high school maths for the site, I'm a refugee from the webmaster stack site, and thought I might find some help here.

The question concerns candle making (in the real world). I'm thinking of purchasing some large pillar candle moulds from a company in Australia (can't find the right size anywhere else) and I need to check that I can melt enough wax to fill a single mould in one go and if not figure out what size boiler I should buy.

Problem is wax is sold in dry weights and the volume is calculated in, well, liquid volume. I don't know how to translate between the two.

  • Volume is V = πr2h.
  • Mould is 100mm diameter and 241mm tall
  • = 7574285.714285708 Cubic millimeters
  • = 7.574285714 cubic liters.

So, the problems are these:

  1. Basically the result doesn't make complete sense to me - it shouldn't be that large! Have I done the conversion incorrectly or is there a difference that I'm unaware of between American and British volume calculations (I'm a Brit).
  2. Candle wax is sold in dry kilograms, I've seen various conversion charts online, but they often seem to be guess work. Is there a simple formula for converting a dry weight of a solid into it's resulting liquid volume.

Apologies if this is too simple or the solution is obvious, and thanks in advance for your help.

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    Your formula has $h\cdot\pi r^2$, and you said the diameter was 100mm, but then you calculated $h\cdot\pi d^2$, which is why you got a volume four times as big as you should have. $r$ is radius, which in this case is 50mm, not 100mm.2012-05-28

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As pointed out in comments, the computation is off by $4$ due to the diameter being twice the radius. A cylinder of radius $50/1000$ meters and height $241/1000$ meters has volume of about $1.89$ liters. Using the wax density of $930$ kg/L yields $1.76$ kg.

By the way, "cubic liters" is incorrect since a liter is a measure of volume.