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Do you know how to tell if a propane tank is full? As in COMPLETELY full? We didn’t, so of course we did what anyone with internet access would do, we consulted The Oracle to find out the answer. What I learned is that, stamped onto the side of a propane tank, should be the Tare Weight (TW), the weight of the tank unfilled. A 20 lb. tank should then weigh 20 lbs. more than the labeled Tare Weight after it has been topped up.

The Tare Weight of our 20 lb. steel tank is 18 lbs.

Why bring this up? Because our tank also has a fancy little gauge on it that, like an automobile fuel gauge, can tell us visually how much propane is in it. When we came to pick up our main propane tank on Wednesday after dropping it off the day prior to have it filled, our gauge did not read full. In fact, it was down what we would consider a fair bit, enough propane to last us quite some time.

Note: We had our propane tank filled shortly before leaving Grenada in November 2011. It only just the other day ran out. You can tell we don’t use all that much propane!

The gauge now reads full, as it should.

Anyway, considering that we didn’t really need to get the tank back that day, and they’re charging a fair amount to fill the tanks ($90.00 EC which equates to $33.33 US for a 20 lb. tank), we wanted to have it FILLED. When I complained, the gentleman I spoke to kindly explained that although he didn’t have any way of checking it right there, if we would leave the tank with him, he’d make sure it was looked after.

When we ultimately picked up the tank yesterday we found that our trusty little gauge read full, as it should have. Unfortunately, I think paying for a full tank in these situations but only receiving a portion of what you pay for is pretty common. In fact, I think it happened to us in Grenada too but because of the inconvenience of leaving the tank with them again (we had planned to set sail the next day) we just accepted the fact that we were ripped off a bit. It may not be a lot of money but it is a PITA. Caveat Emptor.

Just for kicks I checked our 10 lb. aluminum tank. It has a Tare Weight of 9.32 lbs. It weighed approximately 15.5 lbs. indicating that it is still about 60% full.

By the way, the video that I mentioned yesterday finally finished uploading. Scroll down to view it on yesterday’s post if you haven’t already.


  1. I buy by the liter or gal, and was told it is unsafe I to totally fill a tank, but that could have been a new tank is unsafe to fill to the max.

    So you buy by the tank eh. Good info to have.

    • “So you buy by the tank eh. ”

      I have never seen it done otherwise, at least down here.

      There is something different that has to be done the first time a tank is filled. I forget what that is but the guy filling it should know (if you tell him that it’s brand new of course).

  2. I thought those gauges didn’t really work. Aren’t they based on tank pressure whereas the propane is liquid and that’s why you buy based on weight. How can a pressure gauge measure how full of liquid it is? Just asking cause this is what I’ve been told.

  3. do you use propane for cooking?

    • Yes, that’s all we use it for. We have a propane on-demand hot water heater but never turn it on. Also, unlike our friends on Earthling who routinely prepare meals which take a long time to cook, ours are all cooked fairly quickly.

  4. Only Costco charges for what they actually pump into your tank here in Toronto. All of the others, including Cdn Tire, charge a flat rate which can be a rip off. From what I have seen at Costco there have been times, (e.g. January @ -15C) where I think the tank is near empty because there is not enough pressure to create a decent flame. When I get it to Costco they only charge me for half because there was still plenty left in the tank. Of course I could just heat the tank up with a blowtorch or take it into the house to warm up, thereby voiding all of my insurance policies…, life…

    • If you run the tank empty, which we do because we have two tanks, paying a flat rate is not a rip off, assuming of course they actually fill it!

  5. Good to know .. thanks for the info!

  6. But when the tank is ½ full the gauge still reads full because the pressure is the same.

  7. I have a clear 20 lb propane tank for my grill and I love it……First it does not rust and second you can see the level of propane left in the tank……

    • They are nice. The reason we went with steel for our primary tank, aside from the obvious difference in price, was due to the belief that we might be forced to swap our empty tank for a filled one in certain places. That has never happened though so it wouldn’t have mattered.

  8. New tanks need to be purged before being filled. I went a different route, I purchased a composite tank, which are light when empty and you can actually see the liquid remaining. I know when I had it filled it wasn’t really full to the top of the tank, but the filling station weighed the tank to know it had 20lbs.

    • Unless you are there when they weigh it though, how do you really know? In many cases (MOST) we drop off the tank one day, they take it away and fill it offsite, returning it a different day. We never see the process.

  9. I love the fish scale method. I can’t wait to hear the next time you send it away for a refill of 20lbs and when he returns, you weigh it. Show him the missing amount and hand him a percentage of what he asked for!

  10. In Mexico we take the bottles to a propane station and we watch them fill it in 2 minutes. There is a meter that reads the volume in gallons or liters and the attendant knows when it is full. I think there is a pressure valve that bleeds of a stream of propane when it is full. Cost was under $5 US dollars per tank.

    • Nice! We have not come across anything similar in the Caribbean, not to say that it doesn’t exist.

      Edit: Actually that’s not true. I recall doing that once. I think it might have been in the USA though.

      Edit again: Nope. I remember now. Even though I was present when it was filled, we still paid in advance based upon the size of the tank being filled, not the volume of what went into it.

  11. Mike,
    I think the gauge should have a calibration problem.
    Look after something on it that you can turn, maybe the black center piece can be it.
    then measure the weight and calibrate the gauge to indicate that.

    also, it’s possible that the gause is “just for referemce” if it was not designed for the size of your tank.
    If that is true, even if you do find the calibration screw and calibrate it, it will not show the right load.


    • Hi Ricardo

      Why would you believe that the gauge has a calibration problem, if that is actually what you meant? The gauge reads full when it is full and empty when it is empty. It was not reading full when they initially brought it back but did the second time, indicating that they added more propane. They certainly wouldn’t overfill it, if that is possible. I did not weigh the tank myself as I was happy with the reading on the gauge.
      As for it being just for reference, the tank came with the gauge pre-installed on it so I would have to assume that it is definitely meant for that tank.

  12. Propane tanks should only be filled 75-80%. This leaves room for expansion. I have always heard your type gauge is not very accurate.

    • Well AJ, I can tell you first hand that the gauge IS accurate. As I already posted, it reads full when full and empty when there’s nothing left in the tank. What more can we ask for?

  13. Maybe an accurate reading midway?

    • Accurate in what sense? It goes down as we use it and it seems to go down gradually, as one would expect. In other words, it functions the same as any other fuel gauge I have ever known does.

  14. I’m sorry Mike, I ended that post with an iphone smiley face. Didn’t realize it wouldn’t show up. I’ve never had good luck with those gauges but more power to you if yours is accurate. Just purchase a new fiberglass tank to go along with our 20lb steel tank. Once we run out of propane in the steel tank we will be all fiberglass!

    • No worries, AJ. It’s all good. I appreciate the input. Up to this point we have not been forced to swap our tank. Thinking that we would have to was one of the main reasons we didn’t go with fiberglass ourselves.

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