How to Tell If Your Grill's Propane Tank Is Empty

A grill’s propane tank doesn’t have a fuel window, so running out always feels sudden. One minute the grill is going, and the next the flame is fading with burgers still on the grate.

The good news is you don’t need to guess. A grill tank’s level is easy to check with things most kitchens already have, and a couple of quick tests tell you exactly where you stand before you fire anything up.

The Short Answer

Weigh the tank and subtract the tare weight stamped on the collar. That tells you exactly how many pounds of propane remain.

No scale handy? Pour hot water down the side of the tank and run your hand down the same spot. The metal feels warm where there’s only vapor inside and noticeably cooler where liquid propane still sits.

Method One: The Weight Test

This is the most accurate method available without an electronic gauge, since propane’s weight tells you directly how much fuel is left.

1. Find the tare weight, stamped as “TW” followed by a number, on the collar near the valve.
2. Weigh the full tank on a scale. A hanging luggage scale works well for this, since most bathroom scales aren’t accurate with an odd-shaped object like a tank.
3. Subtract the tare weight from the total weight. The result is how many pounds of propane remain.
4. Compare that to the tank’s stated capacity, usually 20 pounds for a standard grill tank, to get a rough percentage.

An Etekcity Digital Luggage Scale handles this well, since it hangs the tank by its handle and reads the total weight directly.

This method takes a couple of minutes, but it’s the closest you’ll get to an exact number without a built-in gauge.

Method Two: The Hot Water Test

This method needs nothing but water, and it works because liquid propane inside the tank is much colder than the surrounding air.

1. Heat a cup or two of water until it’s hot to the touch, but not boiling.
2. With the tank cool and the valve closed, pour the water slowly down one side.
3. Run your hand down that same side of the tank.
4. Feel for the spot where the metal shifts from warm to distinctly cool.
5. That temperature line marks the current propane level inside the tank.

The area with liquid propane draws heat out of the metal faster than the empty, vapor-filled area above it, which is what creates the noticeable temperature difference. This trick only gives a rough level, not an exact weight, but it’s fast and needs no tools at all.

Method Three: The Shake Test

This is the quickest check, though it’s the least precise of the three.

Lift the tank slightly and gently rock it side to side. A tank with plenty of propane left will feel heavy and you may hear or feel liquid sloshing inside.

A tank that feels unusually light, with no sloshing at all, is likely low or empty. This method is best used as a first, rough check before confirming with the weight or water test.

Method Four: A Propane Level Gauge

If you’d rather not test the tank manually every time, a permanent gauge takes the guesswork out entirely.

A GasWatch TVL212 Propane Level Indicator connects between the tank and the regulator and gives you a simple color-coded reading before you even turn on the burners. It also includes a built-in leak detector and an emergency flow limiter, both useful safety features beyond just checking the level.

Attach it once and check it every time you grill, without needing a scale or hot water on hand.

Reading Your Tank’s Stamped Markings

The collar of every propane tank carries information worth understanding before you rely on any of the methods above.

The tare weight, marked “TW,” is the tank’s empty weight and is essential for the weight test. The water capacity, marked “WC,” tells you the tank’s volume rather than its weight, which is a separate number.

You’ll also find a manufacture date stamped as a month and year. Propane tanks need recertification every 12 years from that date, and many exchange and refill stations will refuse to fill a tank that’s expired, regardless of how much propane is left in it.

Confusing an Empty Tank With a Tripped Regulator

Here’s a mix-up worth knowing about before you assume a weak flame means you’re out of propane.

A regulator has a built-in safety feature that limits gas flow if it detects a sudden surge, which can happen simply from opening the tank valve too quickly. When this trips, you get a weak, trickling flame even with a tank that’s still mostly full.

If your tank weighs heavy but the flame is still weak, the problem likely isn’t the propane level at all. Our guide on why your gas grill has a weak flame walks through the regulator reset and the other common causes of this exact symptom.

How Long Does a Tank Actually Last?

This depends on your grill’s burner output and how high you typically run the heat, but a rough estimate helps with planning.

A standard 20-pound tank provides roughly 18 to 20 hours of total cooking time on a mid-size grill running at medium heat. Running consistently on high, or grilling on a larger, multi-burner unit, shortens that considerably.

Our guide to what a grill actually is covers how BTU ratings affect heat output and, indirectly, how quickly a tank burns through its fuel.

Other Grill Tank Sizes You’ll Run Into

The 20-pound tank is the standard size for backyard grilling, but it isn’t the only one that shows up on grilling equipment.

Smaller 1-pound canisters power some tabletop and portable grills, and they’re worth keeping a spare of if you grill on the go often. Our best camping cookware guide covers gear that pairs well with this smaller, portable format.

Some larger grills and most propane smokers use bigger 30 or 40-pound tanks instead of the standard 20. The same weight-test math applies either way, just with a different tare weight stamped on the collar. Our guide to propane smokers covers a popular option built around the standard 20-pound size.

What to Do Once You Confirm It’s Empty

Once you know the tank is genuinely out, you have two options, and each has tradeoffs worth knowing.

Exchange swaps your empty tank for a filled one at a retail cage, usually outside a hardware store or gas station. It’s fast, but exchange tanks are often filled to a standard amount that’s sometimes less than a full 20 pounds.

Refill takes your own tank to a propane dealer or some hardware stores and fills it on the spot, typically to a fuller level and at a lower cost per pound. It takes a few extra minutes but usually gives better value over time.

Keeping a second tank as backup, regardless of which option you prefer, means a low tank never has to end your cookout early. This matters most if you’re already mid-recipe, like grilling corn on the cob, and don’t want a fuel switch to interrupt the timing.

How Cold Weather Changes These Readings

Temperature affects propane more than most people expect, and it’s worth accounting for if you grill through the colder months.

Propane’s internal pressure drops as the outside temperature drops, which can make a tank perform sluggishly even when it technically has plenty of fuel left. This is a pressure issue rather than a fuel-level issue, so the weight test still gives you an accurate reading even in cold weather.

The hot water test becomes less reliable in freezing outdoor temperatures, since the water can cool and start to ice before you finish checking the full height of the tank. The weight test is the more dependable option once temperatures drop.

If you notice sluggish performance specifically in cold weather despite a tank that weighs heavy, that’s expected behavior, not a sign of a problem with the tank or the grill.

When Your Grill’s Tank Also Feeds Other Cooking Gear

Some backyard setups draw propane from a single tank for more than just the main grill, which changes how fast that tank actually empties.

A side burner attached to your grill, or a separate propane smoker running off the same tank, will drain it faster than grilling alone would. If you’re feeding more than one burner off one tank, check the weight more often than you would with a grill-only setup.

Smokers are a common example of this, since many run for hours at a stretch rather than the shorter burst of a typical grilling session. Our guide to propane smokers covers fuel considerations specific to that kind of long, slow cook.

Storing and Handling Your Tank Safely

A few habits keep a propane tank safe between uses, whatever its fuel level.

Store tanks upright, outdoors, and away from direct heat sources or enclosed spaces. Never store a spare tank inside your home, garage, or any enclosed structure.

Keep the valve closed when the tank isn’t connected to the grill, even if there’s propane left inside. Check hose and regulator connections periodically for wear, especially if the tank sees heavy seasonal use.

If you grill on a balcony or in a shared building, check your building’s specific rules on propane storage. Our guide to balcony grilling safety tips and rules covers what’s typically allowed and how to confirm your building’s exact policy.

Why Grills Don’t Come With a Built-In Fuel Gauge

It’s a fair question, since almost every other fuel-powered device you own has one.

Propane sits inside the tank partly as liquid and partly as vapor, and that liquid doesn’t move or settle the way gasoline does in a car’s tank. A simple float-style gauge, the kind that works in a fuel tank, doesn’t translate well to a pressurized cylinder like this.

The gauges that do work, like the level indicator covered above, rely on measuring temperature differences or actual weight rather than a floating sensor, which is why they attach externally rather than sitting inside the tank.

Exchange Tanks vs. Home Fills: Does It Matter for This?

Both filling methods still leave you needing to track the level the same way, but it’s worth knowing the difference going in.

Exchange programs, common at hardware stores and gas stations, swap your empty tank for a pre-filled one. These are sometimes filled to a set amount slightly under a full 20 pounds, which is worth factoring in in the weight-test math above.

A home fill, done at a propane dealer, typically tops the tank off closer to its true capacity and often costs less per pound over time. Either way, the same weight and water tests apply once you own the tank again.

What to Do If You Run Out Mid-Cook

Running out partway through dinner is frustrating, but a couple of backup options keep the meal from being ruined entirely.

An electric grill or indoor option can finish the job if you have one on hand. Our Gotham Steel smokeless grill review covers an indoor-friendly backup that doesn’t rely on propane at all.

If you’re set up for apartment or balcony cooking generally, our roundups of small grills for balconies and patios and portable grills for apartment living include models across several fuel types, so a backup doesn’t have to mean an identical spare tank.

A spare 1-pound canister, kept with your grilling gear, can also power certain portable burners in a pinch. Our small-space grilling accessories you actually need guide covers a few worth keeping on hand for exactly this situation.

Building the Check Into Your Routine

The easiest way to avoid running out mid-cookout is to check before you start, not after the flame is already fading.

Get in the habit of weighing or checking the tank before, not during, a cookout, especially before hosting guests or planning a longer cook. Our guide on how to set up a small patio for grilling covers general setup habits that pair well with a quick pre-cook fuel check.

Keeping a spare tank, already confirmed full, removes the guesswork entirely and means a low reading is never an emergency.

Before You Host a Cookout

A little extra checking before guests arrive prevents the single most awkward version of this problem: running out mid-meal in front of company.

Weigh the tank the day before rather than the morning of, so there’s still time to exchange or refill it if the number comes back lower than expected. If you’re feeding a crowd, plan on a full tank rather than one you’re unsure about, since a multi-hour cookout burns through fuel faster than a quick weeknight dinner.

Keeping a second, already-confirmed-full tank specifically for entertaining removes this entire category of stress.

Common Mistakes to Avoid

• Assuming a weak flame always means an empty tank. A tripped regulator produces the same symptom with plenty of propane left.
• Using a bathroom scale instead of a hanging scale. Tanks balance poorly on a flat platform scale.
• Ignoring the tare weight stamp. Without it, a total weight reading tells you nothing useful.
• Trying to fill an expired tank. Most stations won’t refill a tank more than 12 years past its stamped date.
• Storing a spare tank indoors. Always keep propane tanks outside in an upright position.

Related Guides

• Why Your Gas Grill Has a Weak Flame
• What Is a Grill? Every Type, Explained
• Best Gas Grills Under $500
• Best Gas and Charcoal Grill Combo

The Bottom Line

You don’t need to guess whether a propane tank is empty. Weigh it and subtract the tare weight for an exact answer. Use the hot water trick if you don’t have a scale. Add a gauge if you’d rather check at a glance. If the flame is weak but the tank feels heavy, suspect the regulator instead. Check that before you swap the tank.

Frequently Asked Questions

How can I check my grill's propane level without a gauge?

Two reliable methods work without any tools. Weigh the grill tank on a scale and compare it to the tare weight stamped on the collar, or pour hot water down the side and feel for where the metal turns from warm to cold, which marks the propane level inside.

What does TW mean on a grill's propane tank?

TW stands for tare weight, the weight of the empty tank itself, stamped into the metal collar near the valve. Subtract the tare weight from the tank's current weight on a scale to find out how many pounds of propane are actually left.

How much propane is in a standard 20-pound grill tank?

A standard grill tank holds 20 pounds of propane when full, and its empty tare weight is usually around 17 pounds, so a full tank weighs about 37 pounds total. Weigh the tank and subtract the stamped tare weight to check the exact amount left.

Why does my grill have a weak flame even though the tank feels heavy?

A tank that still has propane in it can still produce a weak flame if the regulator's safety mechanism has tripped. This is a separate issue from an empty tank, and it has its own quick fix.

How long does a 20-pound propane tank last on a grill?

On average, a 20-pound tank provides roughly 18 to 20 hours of cooking time on a mid-size grill at medium heat, though this varies with grill size, burner count, and how high you run the heat.

Is it dangerous to grill with a nearly empty propane tank?

Not dangerous, but unreliable. As a tank empties, internal pressure drops, which can cause a weaker flame and less consistent heat well before the tank is completely out.