How to tell how much propane is left in your tank (before you run out mid-cookout)

There is a special kind of disappointment that hits when the grill sputters out halfway through a Saturday cookout and the burgers are still pink. It happens to everyone eventually, usually with a yard full of hungry people watching. The good news: you never have to guess how much propane is left. A bathroom scale, a cup of warm water, or an inexpensive gauge will tell you in about a minute. Here are four ways to check, from no-tools to most-accurate, and what to do when your tank is running low here in Grass Valley.

The quick answer: how much propane is left in your tank

If you want one reliable answer, weigh the tank. A full 20-pound cylinder weighs around 37 pounds, so the closer yours is to its empty weight, the sooner you will want a fresh one. No scale handy? Pour warm water down the side and feel for the cool line. And if the tank is low or getting old, you can swap it for a full one at our counter in a few minutes. Details on all of it below.

Method 1: Weigh it (the most accurate)

Every propane cylinder has numbers stamped into the collar, the metal ring around the valve. The one you want is the tare weight, marked "TW." That is what your tank weighs completely empty, usually around 17 pounds for a standard 20-pounder.

Here is the math:

• Set the tank on a bathroom scale and note the total weight.

• Subtract the tare weight. What is left is the pounds of propane still in the tank.

• Want gallons? Propane weighs about 4.2 pounds per gallon, so divide the propane weight by 4.2. A full 20-pound tank holds roughly 4.6 gallons.

So a tank that reads 30 pounds on the scale with a TW of 17 has about 13 pounds, or a little over 3 gallons, of propane left. A completely full tank tops out around 37 pounds. This is the only method that gives you a real number instead of an estimate.

Method 2: The warm-water trick (no tools)

No scale? This one costs nothing and takes a minute. Fill a cup or pitcher with warm tap water, not boiling, and pour it slowly down one side of the tank. Then run your hand down that same side.

You will feel a temperature change at a certain point: warm up top, cool below. That cool line is the top of the liquid propane inside. The propane absorbs the heat from the water, so the metal stays cooler wherever gas is still sitting. A cool line near the bottom means you are almost out. It is an estimate rather than an exact reading, but it is more than enough to know whether you will make it through the weekend.

Method 3: Use a gauge

If you would rather not think about it, a gauge does the watching for you. There are a few kinds:

• An inline gauge screws on between the tank valve and your grill's hose and reads the pressure to estimate how full the tank is.

• An analog gauge works like a luggage scale, preset to your tank's tare weight.

• A digital scale gives you a percentage and even an estimated cook time.

One honest note: the pressure-style gauges are handy for a quick glance, but they give you a ballpark rather than an exact amount. The scale-style gauges are really just weighing the tank for you, which is why they tend to be more accurate. Either way, a gauge is a small purchase that takes the guesswork out of your next cookout.

Grab a Gauge While You're in Town

We stock propane gauges, tanks, and everything else for grill season at our BBQ Center on Nevada City Highway.

Visit Our BBQ Center

How long a tank lasts, so you can plan

Knowing your level only helps if you know how fast you burn through it. A full 20-pound tank holds about 420,000 BTUs of energy, which works out to somewhere between 14 and 20 hours of grill time on a mid-size gas grill, depending on how many burners you run and how high. Keep everything cranked to high and you will land closer to 10 hours.

For most families that is a couple of weeks of weeknight dinners or a good stretch of weekend cookouts. The trick is not letting it run to empty at the worst possible moment. A lot of our foothill customers keep a full spare in the garage so they are covered before a weekend barbecue, a camping trip up to Tahoe, or a power outage when the grill or a propane heater becomes the backup plan.

Running low? Swap it at B&C Ace

When your tank is getting light, or you just do not want to risk it, bring the empty 20-pound cylinder by our counter and we will exchange it for a full, inspected tank in a few minutes. A 20-pound tank exchange is $24.99. If you do not have a tank to trade in, a brand-new filled 20-pounder is $69.99.

Need something bigger? We stock new tanks in 11, 20, 30, 40, and 100-pound sizes for RVs, generators, patio heaters, and larger gas grills. And if your current tank is more than 12 years old, which you can check by the date stamped on the collar, an exchange is the easy fix. It hands you a fresh tank that is already certified and ready to go, instead of leaving you to get an old one requalified.

Bring it by the counter and we will check that date for you while we are at it.

Propane tank questions, answered

How can I tell how much propane is left in my tank? Weigh it. Subtract the tare weight stamped on the collar from the total weight, and what is left is the propane. For a quick no-tools check, pour warm water down the side and feel for the cool line.

How much does a full 20-pound propane tank weigh? About 37 pounds. That is roughly 17 pounds of empty tank plus close to 20 pounds of propane, or about 4.6 gallons.

Is a propane tank gauge accurate? Pressure-style gauges give you a useful estimate, not an exact amount. If you want a precise number, weigh the tank or use a scale-style gauge.

How long does a 20-pound tank last on the grill? Roughly 14 to 20 hours of cooking on a mid-size grill, and closer to 10 if you run it hot the whole time. Keep a spare so you are never caught mid-meal.

When should I just swap the tank instead of squeezing out the last bit? If the warm-water line is near the bottom, or the tank is rusty, dented, or more than 12 years past the date stamped on its collar, swap it. A fresh tank is safer and saves you the guesswork.

Where can I exchange a propane tank in Grass Valley? Right here at B&C Ace Home & Garden Center, 2032 Nevada City Highway. A 20-pound exchange is $24.99, and we are open seven days a week.

Don't get caught with an empty tank

Checking your propane takes about a minute, whether you weigh it, use the warm-water trick, or clip on a gauge. Do it before the weekend, not during the cookout. And when it is time for a fresh one, swing by and we will have you swapped and back to grilling in a few minutes.

Swap Your Tank in Minutes

Bring your empty 20 pound cylinder to our counter and leave with a full, inspected tank for $24.99. Open seven days a week.

See Our Store Services

Stop by B&C Ace Home & Garden Center at 2032 Nevada City Highway in Grass Valley, or call us at (530) 273-6105. We are open Monday through Saturday from 7:30 to 7:00 and Sunday from 8:00 to 5:00. You can learn more about our propane exchange and other store services any time.