Home / Preparedness / Backup Power & Fuel / Propane Tank Level Estimator
Fuel Planning Tool

Propane Tank Level Estimator

Weigh your tank, enter the size, and instantly know how much propane is left and how long it will last at your appliance's burn rate.

Estimate your propane level

Weigh your tank on a bathroom scale and enter the current weight below.

Tank weight & appliance

The rated propane capacity of the tank (not total weight).
Weigh the tank as-is with any remaining propane inside.
Enter your appliance's BTU/hr rating to estimate runtime. Leave 0 to skip.
Live results update as you type
Estimated Level

11.0 lbs remaining

Your 20 lb tank is approximately 55% full.

11.0 lbs Propane Left
55% Tank Level
23.6 hrs Est. Runtime

How to use this estimator

Place your propane tank on a bathroom or postal scale and record the total weight. Select your tank size from the dropdown, or enter a custom capacity, then enter the current weight. The tool subtracts the standard tare weight to calculate propane remaining. Optionally enter your appliance's BTU/hr rating (found on its label or manual) to get an estimated runtime.

Tips for success

  • Every propane tank has a tare weight (TW) stamped on the collar, that's the empty weight. Subtract it from your current reading to get propane remaining.
  • A standard 20 lb tank typically has a tare weight of 16–18 lbs, so a full tank weighs about 36–38 lbs total.
  • 1 lb of propane contains about 21,594 BTU. Divide your total BTU content by your appliance's BTU/hr to get runtime.
  • Propane contracts in cold weather, tanks can appear slightly lighter in winter but still contain the same energy.
  • Never fill a tank beyond 80% capacity. Suppliers follow this rule automatically to allow for expansion.

Practical note

This tool uses standard tare weights for common tank sizes. For the most accurate reading, check the TW stamped on your specific tank's collar and enter the exact value if it differs significantly. Runtime estimates assume continuous burn at the listed BTU rate, actual runtime will be longer if your appliance cycles on and off.

Standard tare weights by tank size

  • 20 lb tank: Tare weight approximately 17 lbs, full tank weighs ~37 lbs.
  • 33 lb tank: Tare weight approximately 19 lbs, full tank weighs ~52 lbs.
  • 40 lb tank: Tare weight approximately 22 lbs, full tank weighs ~62 lbs.
  • 100 lb tank: Tare weight approximately 27 lbs, full tank weighs ~127 lbs.
  • 420 lb tank: Tare weight approximately 120 lbs, full tank weighs ~540 lbs.

FAQ

How do I find the tare weight of my tank?

Look at the metal collar at the top of the tank, you'll see "TW" followed by a number stamped into it. That's the tare weight in pounds. For a 20 lb BBQ tank it's typically between 16 and 18 lbs.

How long will a 20 lb tank last on a 10,000 BTU heater?

A full 20 lb tank contains about 431,880 BTU. At 10,000 BTU/hr that's approximately 43 hours of continuous runtime. At 50% tank level (10 lbs remaining) you'd have about 21 hours left.

Can I use a bathroom scale for this?

Yes, a standard bathroom scale works well for tanks up to 100 lbs. For larger 420 lb residential tanks you'd need a commercial platform scale, or you can rely on the gauge on the tank itself (if equipped).

Why is my result showing negative propane?

This can happen if your tank's actual tare weight is heavier than the standard value used here. Check the TW stamped on your tank collar and compare it, if your tank is unusually heavy, it may have a higher tare weight than average.

How do I know my appliance's BTU rating?

Check the label on the appliance (usually on the back or bottom), the owner's manual, or the manufacturer's website. Common ratings: propane space heaters 10,000–30,000 BTU/hr, propane generators 80,000–200,000+ BTU/hr, camp stoves 5,000–20,000 BTU/hr.