Calculate How Much Fire Glass or Lava Rock You Need

Fire Glass calculators 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.

If you are using Lava Rock as a base layer or Filler – Measure from the base of the tray to the top of the burner. This will be the ‘depth’ of your lava rock filler, for the top layer of glass, it is best to use the recommended depth of provided by the manufacturer. 

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!