How Long Does an LPG Cylinder Last? 19 kg vs 47 kg Run-Time Calculator
Last updated: July 2026
A 47 kg propane cylinder runs a 5 kW Greengear LPG generator for about 47 hours at half load. A 19 kg cylinder gives you about 19 hours on the same set.
That’s the short answer. The full answer depends on your generator, your load, and what else is drinking from the same bottle. This page gives you the real figures — and a calculator that does the sums for you.
In 30 seconds:
- A 47 kg cylinder ≈ 47 hours on the 5 kW Greengear at half load — nearly six 8-hour trading days.
- A 19 kg cylinder ≈ 19 hours on the same set — a bit over two trading days.
- The smaller 3 kW set stretches a 47 kg cylinder to roughly 76 hours.
- Load is everything. Full load burns roughly double what half load burns.
- Propane only, never butane — butane stops vaporising below about 2°C.
Not sure which generator you need in the first place? Start with our LPG generator sizing calculator, then come back here to work out your propane.
Why does cylinder size matter? Because running out mid-service costs you sales. A cylinder that dies at 2pm on a festival Saturday doesn’t just stop the generator — it stops the till.
Already know your hours are covered? This page pairs with our running-cost calculator, which turns the same fuel figures into pounds and pence.
The biggest mistake we see? Traders guessing in “days” without knowing their load. A cylinder doesn’t last a number of days — it lasts a number of kilowatt-hours. Pin the load down first and the days take care of themselves.
Quick answer: run times for 19 kg and 47 kg cylinders
These figures use Greengear’s own fuel-consumption numbers from the manual. Half load is a fair average for a real trading day — busy spells push it up, quiet spells pull it down.
| Model | 19 kg at half load | 47 kg at half load | 19 kg at full load | 47 kg at full load |
|---|---|---|---|---|
| GE-3000UK (3 kW) | ~31 hours | ~76 hours | ~15 hours | ~38 hours |
| GE-5000UK (5 kW) | ~19 hours | ~47 hours | ~9 hours | ~24 hours |
| GE-7000UK (7 kW) | ~17 hours | ~42 hours | ~8 hours | ~21 hours |
In trading days: a 47 kg cylinder gives the 5 kW set nearly six 8-hour days at half load. The same bottle on the 3 kW set lasts more than nine days. Treat every figure as an estimate — real-world use varies with weather, load swings and cylinder condition.
Work out your own run time
Pick your generator, your average load and your cylinder. The calculator shows your burn rate, total hours, and how many trading days that covers.
LPG Cylinder Run-Time Calculator
The maths behind it (in plain English)
Greengear publishes fuel consumption in grams per kilowatt-hour. That's simply how many grams of propane the engine burns to make one kilowatt of power for one hour.
Here's a worked example for the 5 kW set at half load:
- Half load on a 5 kW generator = 2.5 kW of draw.
- The GE-5000UK burns ~398 g per kWh.
- 398 g × 2.5 kW = ~995 g of propane an hour — call it 1 kg.
- A 47 kg cylinder ÷ 1 kg an hour = ~47 hours.
- A 19 kg cylinder ÷ 1 kg an hour = ~19 hours.
One quirk worth knowing: the 7 kW set is the most efficient per kilowatt (~318 g/kWh — its higher compression squeezes more energy out of each puff of propane). But it carries bigger loads, so it still empties a cylinder faster.
19 kg vs 47 kg — which should you buy?
19 kg propane — the portable option
Quick figures
- Run time: ~19 hours on the 5 kW set at half load · ~31 hours on the 3 kW
- Handling: one person can move it — just — with a proper bottle trolley
- Swaps: stocked at most forecourts and merchants, easy like-for-like exchange
Best for
Day traders, market stalls and coffee trailers on the 3 kW set. Anyone who moves pitch daily and values light, swappable bottles.
Don't rely on it for
- Festival weekends on a 5 kW or 7 kW set — you'll be changing bottles mid-service.
- Heavy winter draw — smaller bottles struggle to vaporise fast enough in the cold.
47 kg propane — the workhorse
Quick figures
- Run time: ~47 hours on the 5 kW set at half load · ~76 hours on the 3 kW
- Handling: a two-person move — the full bottle weighs well over 80 kg with the steel
- Supply: delivered or collected from LPG merchants rather than forecourts
Best for
Static pitches, festival weekends and any 5 kW or 7 kW setup. One bottle covers most of a week's trading, and the bigger liquid volume vaporises more propane per hour — a real advantage in cold weather.
Don't rely on it for
- Setups where one person loads and unloads alone every day.
- Vehicles without a proper secured, ventilated cylinder position for the size. Our LPG cylinder sizes guide covers safe placement and which size fits which vehicle.
Don't forget the cooking propane on top
Your generator is rarely the only thing on LPG. Fryers, griddles and bain maries drink from their own bottle — or worse, from the generator's.
A quick rule of thumb: cooking appliances burn about 0.07 kg of propane per kW of burner rating per hour of actual use. A 7 kW of burners running flat out uses roughly half a kilo an hour.
Run the generator and the cooking from separate cylinders where you can. It makes run-time sums honest and stops a hungry fryer starving your power. Planning a multi-day event? Our Festival Power Planner adds cooking load and a safety margin for you.
Home backup: how long will a cylinder keep the house running?
Plenty of Greengear owners buy for power cuts, not pitches. The same maths applies — and the numbers are reassuring.
A typical household essentials load — fridge, freezer, lights, router, phone charging and the TV — sits around 1 kW. On the 3 kW Greengear, that's roughly 0.44 kg of propane an hour:
- 19 kg cylinder: ~43 hours of continuous essentials power.
- 47 kg cylinder: ~106 hours — more than four days, non-stop.
Run it only when you need it — a few hours morning and evening — and one 47 kg cylinder can see out a week-long outage. Always run the generator outdoors, well away from doors and windows; the exhaust contains carbon monoxide.
When the cylinder can't keep up: frosting and off-take
Propane leaves the cylinder as gas, but it's stored as liquid. Boiling that liquid into gas takes heat, which the cylinder pulls from the air around it.
Draw hard on a cold day and the bottle can't grab heat fast enough. Pressure sags, a frost line creeps up the steel, and the generator hunts or stalls even with propane left inside.
The fixes, in order:
- Go bigger. A 47 kg cylinder holds more liquid, so it vaporises more gas per hour than a 19 kg.
- Twin up. Two cylinders on an automatic changeover share the draw and swap over without a mid-service scramble.
- Keep bottles upright and outside. Never lay a propane cylinder down to "warm it up", and never take it indoors.
Whatever the setup, use the right current-standard hose and regulator — our LPG hose and regulator guide covers the UK rules in plain English.
Five ways to get more hours from every cylinder
- Size the generator to your real draw. An oversized set loafing at 20% load wastes fuel per useful kilowatt.
- Switch off what's idling. An urn held at temperature all afternoon for three teas is run time you'll want back at 5pm.
- Weigh your cylinders. The empty (tare) weight is stamped on the collar. Full minus tare = propane left. No guessing.
- Spread big draws. Don't let the fryer recover, the urn heat and the fridge compressor kick in all at once if you can stagger them.
- Track a real day. Weigh the bottle before and after one full service. That single number beats every estimate on this page.
Why trust Greengear on fuel figures? Greengear builds dedicated LPG generators — factory-built for propane, not petrol engines with a kit added. It's a brand within the Cavagna Group, a world leader in compressed-gas control equipment. The consumption figures in this article come straight from the Greengear manual.
MobCater is a UK distributor for the Greengear range. The mid-size GE-5000UK (from £949) is the one most food vans end up with — or browse the full LPG generator range from £649.
FAQs: LPG cylinder run times
How long does a 47 kg propane cylinder last on an LPG generator?
About 47 hours on a 5 kW Greengear at half load, about 76 hours on the 3 kW set, and about 42 hours on the 7 kW. At full load, roughly halve those figures.
How long does a 19 kg propane cylinder last on a generator?
About 19 hours on the 5 kW Greengear at half load, about 31 hours on the 3 kW set, and about 17 hours on the 7 kW. That's two to four 8-hour trading days depending on the model.
Should I run my generator on propane or butane?
Propane, always. Butane stops vaporising below about 2°C, so it fails exactly when UK outdoor traders need it most. Commercial mobile catering equipment in the UK runs on propane.
Can I use a 13 kg patio bottle on a commercial setup?
It's the wrong tool. Patio and camping bottles are made for barbecues and leisure use, and their off-take struggles under sustained commercial draw. Use 19 kg or 47 kg propane cylinders with the correct regulator.
Why does my propane cylinder frost up?
You're drawing gas faster than the liquid propane can boil off. The cylinder chills itself, pressure drops, and frost marks the liquid level. Move to a bigger cylinder or twin two together with an automatic changeover.
How do I tell how much propane is left in a cylinder?
Weigh it. The empty (tare) weight is stamped on the cylinder collar — the difference between what your scales say and the tare weight is the propane left inside. It's the only accurate method.
How many cylinders do I need for a 3-day festival?
A 5 kW set at half load for three 8-hour days burns roughly 24 kg of propane. Add a safety margin and that's one 47 kg cylinder, or two 19 kg cylinders on a changeover — before cooking propane, which needs its own sum.
Does full load really use twice the propane of half load?
Near enough, yes. Fuel burn tracks the power you draw, so doubling the load roughly doubles the kilograms per hour and halves your run time. That's why knowing your real load matters more than the size on the badge.