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Calculate How Much Fire Glass or Lava Rock You Need

Fire Glass Calculators

Calculators for Fire Glass or Lava Rock are a great tool to help you work out accurately how much fire glass you need for your fire feature.

Lava Rock is much less dense than Fire Glass, you get about twice the volume of lava rock per pound (lb). Using a Fire Glass Calculator to establish the quantity needed would give you false information.  It helps to have a calculator specifically for Lava Rock.

You’ll find we have both on The Magic Of Fire.


How To Use the Fire Glass or Lava Rock Calculators

These calculators are calibrated for inches only, so please measure your fire features dimensions in inches.  

● Be sure when measuring the diameter of round fire pits that you are measuring across the center point of the fire pit.

● Do not enter fractions only whole numbers.

● The results from the calculators are in pounds weight.

● Square, Linear, and Rectangular fire features can all use the same calculator. Just enter the length and width and depth.

Using Lava Rock

If you are using Lava Rock as a filler and then placing fire glass on top  – Measure from the base of the tray to just over the top of the burner. This will be the ‘depth’ of your lava rock filler. For the depth of the top layer of glass over and above the burner, it is best to use the recommended depth of provided by the manufacturer.  American Fire Glass recommend 2″ above the burner for Natural Gas applications but less for propane!  

Generally, burners used with Natural Gas can have a deeper layer of fire glass than Propane as Natural Gas is lighter than air and will naturally want to rise up through the fire glass.  Propane is heavier than air and if obstructed, may sink down into the fire pit structure or accumulate within the burner.  Needless to say, this is not advisable! So heed the manufacturers advise!