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How to Check Propane Level in Large Tank

How to Check Propane Level in Large Tank- 2 Easy Techniques

Large propane tanks are tricky. You can never be sure whether your tank is full or running low on gas.

Of course, keeping your tank filled is important- nothing can be as embarrassing as being caught out at the most untimely moment. That’s why you often need to check the tank to avoid the inconvenience of your appliances stopping working when you desperately need them.

An out-of-gas call can also be expensive since it requires a qualified technician to perform a leak test to meet federal laws in some areas. The good news is that there are two simple ways of inspecting whether the tank is filled or near empty.

In this post, we will look at these straightforward methods and some of the unmistakable signs that point to a tank that needs refilling.

First, here is how to check propane level in large tank.

How to check propane level in large tank

Here are the easiest techniques for checking your propane tank gas level:

Technique 1: Reading the Gauge

Most underground and above ground tanks often come with a functional float gauge system to help you know when it’s running low.

Better yet, these types of propane gauges are extremely easy to read and will eliminate the hustle associated with trying to tell the amount of gas left in a large propane tank.

Follow these steps to check the propane level in a large tank using the built-in gauge:

Step 1:  Locate the gauge

Check around the tank and locate the gauge- this is typically a floating accessory inside the tank.

Step 2: Get the readings

The gauge records the estimated remaining gas on the dial. Your next step is, therefore, to read this dial.

You will notice a value anywhere from 10 to 80. This represents a percentage of the tank’s roughly calculated level of propane.

It’s interpreted as follows:

If it shows 50, you currently have roughly 50 percent of the tank remaining.

The question is: how much propane do you exactly have?


  • Make the percentage a decimal.
  • Next, multiply the resulting decimal by your tank’s total gas capacity.

To illustrate:

Let’s say the gauge read 50 (in decimal= .50).

Assuming your tank’s maximum capacity is 500 lbs, the gas in your tank = .50 x 500 lbs.  = 250 gallons (this is the volume of gas you have)!

The chart below shows an estimate of how much propane is left in the tank based on tank size and the gauge value (10 to 80) and can be a quicker way of approximating how much propane is in there:

Gauge Reading (reading)120 Gallon Propane Tank250 Gallon Propane Tank500 Gallon Propane Tank1000 Gallon Propane Tank
80%96 gallons200 gallons400 gallons800 gallons
70%84 gallons175 gallons350 gallons700 gallons
60%72 gallons150 gallons300 gallons600 gallons
50%60 gallons125 gallons250 gallons500 gallons
40%48 gallons100 gallons200 gallons400 gallons
30%36 gallons75 gallons150 gallons300 gallons
20%24 gallons50 gallons100 gallons200 gallons
10%12 gallons25 gallons50 gallons100 gallons

How long does a propane tank last for a house

So, how long will the propane last?

I demonstrate how to figure this out in this final section.

Step 1: Take the gauge readings

Check the gauge and record the amount of propane gas (in gallons) remaining in the tank. To save time, refer to the previous chart.

Step 2: Check the BTU ratings of the appliances you’re running

The remaining running time comes down to the energy your various appliances need to operate efficiently, so next, you need to record their BTU ratings.

For example, clothes dryers average roughly 35,000 BTUs/hour, stoves 65,000 BTUs/hour, ovens 25,000 BTUs/hour, and regular water heaters 45,000 BTUs/hour.

Step 3: Calculate the remaining running time

To determine how much longer your appliance can run, simply divide the BTUs of 1 gallon of propane (92000 BTUs) by the BTU value of your appliance.

We will take the example of an oven to give you an idea of how this is worked out:

  • Oven BTUs (average)- 25,000
  • 1-gallon of propane BTUs (standard value)- 92,000


With the above example, then you have 3.68 hours of running time left, approximately (92,000 BTUs / 25,000 BTUs per hour = 3.68 hours). You can thus cook with the oven for 3 hours and 41 minutes before a refill is required.

Symptoms of overfilled propane tank

Technique 2: Use a propane tank level indicator

A common method for measuring gas levels in small propane tanks is using a bathroom scale. You can’t use the ‘scale weight’ method on big tanks and have to think of alternatives.

One option is investing in a reliable propane tank gauge level indicator for a large tank, such as this in-line propane tank gauge.

All you have to do to have it read the gas level accurately is install the gauge – it attaches easily to propane tanks with external acme threads. It can work for bigger tanks, including 100 lb cylinders with the right adapter.

More importantly, these accessories give consistent results, so they’re extremely worthy if you get a compatible one.

What size propane tank for grill

How to check propane tank level- signs propane tank is low

If both methods appear like too much hassle or cannot work for your situation, you can try to tell if your tank is due for a refill by keeping an eye on the telltale signs.

To help you out here is how to tell if the home propane tank is empty (the signs are quite similar and are the same even for the largest tanks) using the two clearest warnings:

1. The Flame on your appliances is not that strong

A weak or sputtering flame is probably a sign that you’re running low on gas– you see, when propane is getting low, your appliances will not be receiving adequate fuel hence you might note that they’re no longer burning steadily.

2. It goes off

Some large propane tanks have safety features that automatically shut their gas supply when gas drops below acceptable levels.

These lockout devices are part of the regulators (typically in small domestic/industrial systems and home central heating systems) and help prevent problems associated with running out of propane, such as fires or explosions.

The integrated gauge is your safest bet when it comes to checking how much gas is in your large tank. It removes all the guesswork and works for any large tank equipped with one.

The other method- mostly for the not-so-large tanks- is an aftermarket propane tank level indicator.

Choose the option that is most practical for your situation.

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