How Much Beer is Left in my Keg?

This week I look at a simple way to determine how much beer you have left in your kegs using the weight-to-volume tool in BeerSmith.

Many brewers, myself included, like to keep one or two regular beers on tap at all times. Eventually this becomes an inventory management issue, as you need to have some idea how much of a particular beer you have left to decide when you need to brew to restock.

Ignoring for a moment the problems of lead time to get the beer brewed and mature, a key piece of information is having a solid measure of exactly how much beer you have in inventory. If you keg this can be a challenge as lifting the keg will tell you roughly how much beer is in it but won’t give you an exact volume.

The BeerSmith Weight to Volume Tool

To solve this problem, some years ago I added the Weight to Volume Tool to BeerSmith. This tool lets you weigh your kegs (or other vessels) and calculate the volume remaining based on the weight and empty weight of the keg.

To use the tool you do need to know the empty weight of the keg so you may want to weigh a keg before filling it. In my case, I primarily use standard ball lock Corney kegs (5 gal/19 l size) which weigh 9.29 lb (4.21 kg) empty and I also use the newer ball lock Slimline Torpedo kegs which weight 8.5 lb (3.86 kg). If you have a different keg type, just weigh an empty one using your grain scale and record the weight in your notes for future use.

To determine how much beer is left in your partially filled keg, simply weigh it with your grain scale. Next enter that weight into the Current Container Weight field. Enter the Empty Container Weight you recorded earlier along with the Specific (final) gravity of the beer if known. If you are not sure about the final gravity of the beer, you can use 1.015 as a reasonable value as the gravity will not affect the calculation much. Once you have entered these values into the tool the Estimated Volume of the beer will be shown at the bottom.

This tool is available under Tools->Weight-Vol on the menu for both BeerSmith 3 desktop and BeerSmith mobile. It will also shortly be available as an online tool on for Gold+ users.

Leave a comment blow if you have other books you have enjoyed. Thank you for joining me this week on the BeersSmith blog – please subscribe to the newsletter or listen to my video podcast for more great material on homebrewing.

3 thoughts on “How Much Beer is Left in my Keg?”

  1. This is an interesting tool that I did not know about. I am quite interested in using this to determine exactly how much went INTO the keg as well. I often have a partially full 3rd keg from a batch and I never really know what my final volume was.

  2. Thanks for this tool! I just built my keg weighing system using a Raspberry Pi Pico to read load cells. Instead of knowing the starting weight, I simply show “Pints = X.xx” based how much less the keg weighs after each pour.

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