The Best Smart Propane Tank Level Monitors

Propane always runs out at the worst moment. The burgers are half done, or the camper's furnace quits overnight, or the water heater goes cold on a Sunday. About 5.7 million U.S. households heat with propane, and more than 63% of American homes own a grill or smoker, so a lot of us are guessing at a steel cylinder we can't see inside of. A smart monitor turns that guess into a number on your phone. It's a small fix for a genuinely annoying problem.

None of these read propane directly, though. Ultrasonic sensors bounce a sound wave through the tank bottom and infer the liquid height, which is good to about ±10% — better than the analog dial gauges that miss by 20% or more, but not exact. Pressure gauges get worse as it gets colder, because propane vapor pressure falls from roughly 110 psi at 70°F to about 24 psi near 0°F. And most of these devices are Bluetooth, so "remote" really means the length of your driveway.

So think about where you'll be standing when you want the answer. On the patio, Bluetooth is plenty. Three states away from your camper, you'll need a bridge on your home network. Tank size matters too — a 20-pound BBQ cylinder needs a bottom-mount sensor, not a clip-on dial reader. We think that the Mopeka Pro Check Universal two-sensor bundle is the best smart propane tank level monitor for most people, and that the Pro Check Universal bundle with the LED display is the one to buy if you want a readout mounted in your RV.

Buy one of these if you've ever run out of propane and had to deal with it — mid-cook, mid-trip or mid-January. Grillers get the most obvious benefit, since a standard 20-pound cylinder holds about 4.6 gallons and a grill on high burns roughly 1.5 to 2 pounds an hour, which is only 8 to 11 hours of cooking. RV owners get more, because you can't heft a strapped-down tank to guess its weight. And if you heat with propane, an alert at the 20% mark that the industry recommends as a refill threshold is worth real money in avoided emergency delivery surcharges.

This guide covers monitors for portable and above-ground cylinders — BBQ tanks, RV and camper bottles, patio heaters and larger above-ground LPG tanks. It doesn't cover buried tanks, which need equipment your propane dealer usually installs, and it doesn't cover dealer-side telemetry systems. If your tank has a working dial gauge you can see from a window, and you're never away from home for long, you probably don't need any of this.

We started from spec sheets, published technical guidance and owner feedback themes, then judged every product against the same five things. Sensing: ultrasonic liquid-level reading beats pressure, because vapor pressure falls apart in the cold. Range: we took manufacturer Bluetooth figures and discounted them for the steel and concrete owners actually install around. Tank fit: each device had to state the cylinder sizes it supports, and small BBQ tanks rule out clip-on dial readers. App: custom low-level alarms, multiple tanks and a pairing process people don't complain about. Upkeep: battery life measured in years rather than months, and no ongoing plan required for the alert that keeps you from running dry.

If you want one checker you can carry from tank to tank: The Truma Gas Fill Level Check 50501-01 ($83.54) — The Truma LevelCheck is a handheld ultrasonic reader rather than a mounted sensor. You hold it flat against the side of the bottle and an LED tells you whether there's liquid at that height, and it works on steel and aluminum cylinders from 200 to 350mm in diameter. There's even a flashlight built in for the dark corner of a storage bay. What you give up is everything automatic: no app, no alerts, no reading unless you walk out and take it. It also won't work on fillable tank-style bottles, and some owners report units that read empty on tanks that clearly weren't.

Here's what the research turned up beyond our picks — not everything sold in this category, but the products that came up often enough to warrant a look.

The Flame King Smart Wireless Propane Tank Scale ($19.99) — The Flame King Smart Propane Tank Scale takes a different approach: the tank sits on a Bluetooth scale, and weight is inherently the most direct measure of how much propane you have. It handles 20-, 30- and 40-pound cylinders and fits inside many grill cabinets. But owner feedback is split hard, and the complaints cluster around the same places — an app that refuses to pair, a power switch mounted underneath where you can't reach it with a tank on top, and a flimsy battery door on the two AA cells it needs. Manufacturer support seems responsive about replacements. If your grill cabinet fits it and you like the idea of a direct weight reading, it's worth a shot, but the ultrasonic sensors are the safer buy.

Ultrasonic sensors are only as good as their contact with the tank. Clean the bottom with alcohol first, apply the acoustic coupling grease, and set the sensor flat and centered — the app's bubble level exists for a reason. Use the included ring so the tank's weight rests on the ring, not the sensor, or you'll be re-seating it after every refill. Aluminum cylinders need an adhesive collar, since magnets won't grip. Once it's reading, set your low alert around 20%, which is the refill threshold propane industry groups recommend. That buffer isn't just convenience. Under NFPA 58, a system that runs completely empty needs a licensed technician to pressure test it and relight the pilots before service resumes.

For this guide:

• We read the manufacturer specifications and product documentation for every monitor here, comparing stated accuracy, tank compatibility, connection type and battery ratings side by side.
• We drew on published technical guidance from propane industry and safety organizations for the underlying facts about vapor pressure, gauge accuracy and refill thresholds.
• We read through owner feedback looking for repeated themes — pairing failures, mounting problems, battery complaints — rather than treating any single account as decisive.
• We read owner reviews on every listing, weighted toward the critical ones, because that is where the recurring failures show up.
• We have a systematic way of automatically fetching the latest prices, so the numbers on this page stay current.
• This is a research-focused guide, so the team may not own every product listed — though we often do own the top winners, which gives us extra context for the recommendations.
• We don't accept free products, and the retailer commission never changes which product we recommend.