When To Fill A Propane Tank – All You Should Know

filling a propane tank

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Your freshly filled propane tank will need refilling over time. So, you need proper planning to avoid interruption when you least expect it. Because let us face it, nothing sucks more than running out of gas when you have a backyard party at its peak. Everyone is at the top of the party mood, and then what? Your propane tank has breathed out its last!

All that results from one problem: knowing when to fill the propane tank. It is a challenge for most users. And if this is something you struggle with, worry no more. This article will elaborate on everything you need to know so you can save yourself from such frustrations. 

You will learn to tell how much propane is left, whether to empty the propane tank before refilling, the best season for home propane refill and so much more.

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How Do I Know How Much Propane Is Left?

As mentioned above, many users cannot tell how much propane remains in the tank. However, this is easier than you think. Below, we will look at some simple methods you can use to tell how much propane remains.

Propane Gauge

A propane gauge is the most common and convenient way of knowing how much remains in the tank. We know most small tanks do not have gas gauges. However, do not worry, as you can buy from your nearest hardware store and install it. 

As for residential tanks, they come preinstalled with gauges to let you monitor the gas level. Propane gauges have three sections. Each section is marked in green, yellow, and red for easy use.

Nonetheless, different types of gauges exist, including analog and digital forms. Analog gauges are easy-to-read color-coded dials you read manually. In contrast, the digital ones use sensors to remotely monitor and send the propane data through mobile or desktop apps. 

So, how do you read the tank gauge?

When filled, the needle will hover over the green region. As the gas level reduces, the needle position moves in an anticlockwise direction towards the yellow section.

Once it hits the yellow section, the tank is half full. From this part, the needle moves towards the red part of the gauge. If it falls within the red region, you know it’s time to re-order.

Remember that the rule of thumb is not to let the level go below 20% of the tank capacity for safety reasons. If you let this happen, the fuel system needs resetting to ensure it is correct. And that requires the inspection of professional technicians. Obviously, this is an extra cost you want to avoid.

Another crucial thing to note with the gauges is that the indicator displays the percentage level, not the actual volume. To get the amount in gallons, multiply the percentage with the tank capacity. 

For example, if the gauge indicates 60% on your 500-gallon tank, only 300 gallons of propane remains. That is 0.6×500=300 gallons.

The Weight of the Propane Tank

weight scale

What if you own a small tank? If you own a 20lb tank, checking its weight can be a hassle-free method to know the amount of propane gas in the tank when you want.

One way to do this is by lifting the tank from the ground. If you are used to holding it when full, you can know how much gas remains after some time by just lifting it. You can even slightly shake it side to side. Here’s how much an empty tank weighs.

Shaking it will cause the liquid inside to slosh, with the sloshing being heavier the more the gas it contains.

But for better accuracy, you can weigh the tank instead. With this method, you have to keep note of two figures that appear on the tank side: Tare Weight(TW) and the Water Capacity(WC). The TW mark indicates the weight of the empty tank, while WC is the amount of propane gas in the tank.

Using this method is easy if you have a weighing scale in your house. All you have to do is place the tank on the scale and note the reading. Next, subtract the tare weight from this figure. The number you get is the remaining amount of the propane in the tank.

Let’s crunch the numbers here for better clarity. The tare weight of a 20-lb tank is usually 17 lbs, and the tank can hold 20 lbs of propane when full. The total weight is then 37 lbs (17 lbs+20 lbs). Therefore, if the current total reading on the scale is 30 lbs, how much gas remains in the tank? The answer is 13lbs(30lbs-17lbs)

If the Flame Is Weak/Sputtering on Propane Appliances

Have you ever noted how appliances on a newly filled tank produce vibrant flames? When freshly filled, the pressure in the tank is at its highest level. It is the optimal pressure for the functioning of gas appliances.

However, as the level goes down, pressure reduces resulting in a weak flame. In fact, at some point, the pilot light of heaters might even go out entirely. 

The other thing is the appearance and behavior of the flame. At low propane levels, the flame produces a sputtering noise. The reason for this is the imbalance in propane air/mixture. 

You see, the right propane-air mixture is essential for a firm flame. As the propane level goes down, the air in the mixture increases, creating an unstable flame.

Does a Propane Tank Have to Be Empty to Refill?

The propane tank doesn’t have to be empty before doing a home propane refill. Most suppliers check the amount of gas in the tank and then fill it. In other words, you only pay for what you should. 

However, some unscrupulous vendors might charge for the entire tank capacity, regardless of the amount remaining. Therefore, it is essential to choose your vendors wisely to avoid getting scammed.

Also, remember the 80/20 rule of when to fill propane tanks. Only 80% of the tank should be filled, leaving a buffer for expansion caused by temperature changes. Propane is a volatile substance, and the space is for safety reasons.

Concerning this is the need to maintain the minimum propane level above 20% of the tank capacity. So, while you do not have to wait for the tank to be empty, the above rules still determine how much and at what level you can do a home propane refill.

Besides, there are several reasons for not letting your tank run out.

Compromising the Propane Supply System

Emptying the propane tank before refilling disrupts the propane usage system. Gas leaks, rusting, and damage to the tank’s structural integrity are some of the issues to expect. Before filling the tank, you will require an inspection at an extra cost. 

Appliances Will Fail to Work

One of the reasons for not letting the gas go below the minimum level is the inconvenience it can cause. Not draining the entire tank keeps some appliances working before you receive a fresh supply. That means essential appliances keep working.

To Avoid Emergency Refills

A plethora of issues can disrupt the supply of propane: bad weather, road maintenance works, unanticipated supply shortages, etc. Regularly refilling your residential propane tanks before they run out means you anticipate and adequately prepare for disruptions beyond your control.


When filling propane, they charge you only for the amount of propane you order. You can use that opportunity to only budget for a specific amount, enabling you to cater to other budgetary needs. So why wait to empty and make an order for the whole tank?

What Time of the Year Is the Cheapest to Refill a Propane Tank?

calendar numbers on the table

Gas prices are subject to changes like most other commodities. Forces of demand and supply drive these price fluctuations, which also depend majorly on seasons. As a result, demand for propane spikes mainly during the winter season, although this can also happen during the summer.

Summer seasons involve plenty of outdoor activities, including summer camping and vacationing. During this period, there is a lot of heating, hot showers, refrigeration, pool heater, water heater, grilling, and cooking. All this requires plenty of propane usage, spiking some level of demand for it.

However, the winter season has the highest demand for propane, especially considering the heavy heating requirements. Entire houses need heating to prevent a myriad of health and property damage.

So when is the cheapest time to refill your propane tank? As mentioned, summer can be a cost-effective refilling time compared to winter, but fall is the best time. Fall is considered a shoulder season between winter and summer. 

At this time of the year, demand is low. Consequently, this is the time suppliers carry out promotional campaigns, including offering incentives and lowering prices to win over customers. 

Other marketing gimmicks include discount bulk buying and locked agreements. The low-demand fall season is the time to look out for propane supply deals and save money!

How Do You Refill Your Propane Tank?

You probably know by now that propane is a volatile fuel that requires delicate handling. For that reason, only qualified professionals do the refilling. 

So, all you need is to keep tabs on the amount of propane in the tank and reorder on time. Most providers are prompt in fulfilling order requests. As a matter of fact, some propane service companies collaborate with customers to make successful propane delivery schedules. 

Propane company installs digital sensors that relay information to their systems. Once the tank reaches the minimum levels, it alerts them, and they remind you it’s time for propane delivery.
Without a propane tank monitoring system, you’ll have to set up a reminder to check your gauge regularly. With small portable propane tanks, you can refill in legally designated places such as gas stations. Tank swapping is also a popular option you can explore. 

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Ryan McCabe

Ryan McCabe

Ryan is a home and small business energy expert, having overseen retail propane, heating oil, and HVAC services companies. On ComparePropane, Ryan writes about things that people should know when shopping for or using propane in their homes and businesses. 

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