What Size LPG Generator Do I Need for Mobile Catering? Sizing Calculator & Appliance Loads (2026)
Last updated: May 2026
Picking the right size LPG generator is the difference between trading without a stutter and tripping out every time the fryer hits temperature. For most UK mobile caterers, the answer sits between 3 kW and 8 kW — small coffee trailers run happily on a 3 kW propane unit from £1,495, while a fully-loaded burger van or hog roast pitch needs 7 to 8 kW (from around £2,395) to absorb start-up surges without browning out.
An LPG generator sized at roughly 1.5 times your steady-state load is the accepted standard for mobile catering. That’s the figure most engineers, propane suppliers, and trailer fitters quote for outdoor commercial use, because it gives motors and heating elements the inrush headroom they need on cold mornings without leaving you paying for kilowatts you’ll never draw.
Last updated: May 2026
Quick Verdict — Which Generator for Which Setup?
If you just want the headline answer, here it is. Drop your appliance loads into the calculator further down to confirm. All three picks below run on propane, all have UK plugs, and all sit inside the price bands MobCater customers actually buy from.
| Your setup | Typical running load | Recommended generator | Rated output | Approx. price from |
|---|---|---|---|---|
| Mobile coffee trailer — espresso machine + grinder + water boiler + lights + card reader | 1.8 – 2.4 kW | Greengear GE-3000UK | 2.8 kW (3.1 kW peak) | from £1,495 |
| Burger van or street-food trailer — fryer + griddle + bain marie + extractor + fridge | 3.0 – 4.5 kW | Greengear GE-5000UK or GearGB GCE5000B | 5.0 kW (5.5 kW peak) | from £1,895 |
| Large event setup — full kitchen + drinks fridge + freezer + lighting + PA | 4.5 – 6.5 kW | Greengear GE-7000UK or GearGB GCE8000B | 7.0 – 8.0 kW (7.5 – 8.0 kW peak) | from £2,395 |
For anything bigger than a single trailer — twin units, large hog-roast operations, or off-grid food festivals — step up to a 10 to 12 kVA frame like the Vanguard-engined GearGB GCE12000VL. Anything smaller than the GE-3000UK won’t reliably start a commercial espresso machine, so don’t be tempted by the 2 kW camping inverters you see on Amazon.
Why Generator Sizing Matters More Than the Spec Sheet Suggests
Get the sizing wrong and one of two unhappy things happens. Under-size and the generator either trips out under load or runs flat-out for hours, eating propane and shortening engine life. Over-size and you’ve spent £700 more than you needed, you’re lugging an extra 40 kg of frame around, and you’re burning unnecessary propane every shift because a generator running at 30 % of its rated output is at its least efficient.
The number that matters is rated output (sometimes called continuous output), not maximum output. Maximum is what the alternator can produce for short bursts — handy for handling motor inrush — but the rated figure is what it can deliver hour after hour without overheating. Always size off rated output and treat the maximum figure as start-up headroom.
The second factor most operators miss is inrush current. A fridge compressor or extractor motor pulls roughly three times its running wattage for the first second or two of start-up. If your steady-state load is 3 kW and a fridge cycles on, the generator briefly sees 4 to 4.5 kW. A 3 kW generator can’t ride that out cleanly. A 5 kW generator will. This is exactly what the 1.5x headroom rule is designed to cover.
Appliance Loads — What Mobile Catering Equipment Actually Draws
Before you can size a generator, you need to know what each item in your trailer pulls. The figures below are typical UK 230 V wattages for the equipment we sell and service. Where appliances are dual-fuel (LPG primary, mains-electric for control circuits and elements), we’ve listed both the LPG-mode electrical draw and the full-electric mode draw separately — that distinction matters because most mobile coffee operators run dual-fuel machines in LPG mode through the generator and only switch to full-electric when they’re plugged into mains at home.
| Appliance | Running watts | Start-up surge | Notes |
|---|---|---|---|
| Fracino Contempo CON2ELPG (LPG mode, controls + pump only) | 350 W | ~400 W | Auxiliary electric for boiler controls, pump, display |
| Fracino Contempo CON2ELPG (full electric mode) | 2,850 W | 3,200 W | Only used when on mains hookup, not generator |
| Commercial coffee grinder (Mazzer / Eureka) | 350 – 450 W | 700 W | Motor surge on start |
| Fracino Atlantis Mini Gas water boiler | 50 W (controls only) | 60 W | The only LPG water boiler in the UK — propane fires the burner |
| Single-pan LPG fryer (controls + ignition) | 50 – 100 W | 100 W | Burner runs on propane |
| Twin-pan LPG fryer (controls + ignition) | 100 – 150 W | 200 W | Burner runs on propane |
| Electric fryer (single tank) | 2,800 – 3,200 W | 3,200 W | Avoid on smaller generators |
| LPG griddle (electronic ignition only) | 40 W | 40 W | Burner is propane |
| LPG bain marie | 30 – 60 W | 60 W | Controls and pilot only |
| Commercial extractor fan | 180 – 400 W | 900 W | Motor start surge |
| Under-counter fridge (commercial) | 240 W average | 720 W | Compressor cycles 30-50 % of the time |
| Chest freezer (mobile catering) | 180 W average | 540 W | Compressor cycles 25-40 % of the time |
| LED light bar (full kit) | 60 – 100 W | 100 W | No surge |
| Card reader + phone + Wi-Fi router | 40 W | 40 W | Negligible |
| EPOS till tablet + receipt printer | 60 W | 80 W | Negligible |
| Hot water urn (electric, 10 L) | 2,500 W | 2,500 W | Use Atlantis Mini Gas instead — LPG saves load |
Two things will jump out. First, anything LPG-powered (coffee machine on gas, fryers, griddles, water boilers, bain maries) draws almost nothing electrically — the propane is doing the heavy lifting. Second, anything heating with electricity (kettles, urns, electric fryers, electric coffee machines on mains mode) is what eats your generator capacity. The whole point of an LPG-focused mobile setup is to push the heating load onto propane and keep the generator small.
The Sizing Formula — How to Calculate What You Need
Four steps. None of this needs spreadsheets — back of an envelope is fine.
- Add up the running watts of every appliance that will be on at the same time during your busiest moment of service. Be honest — if the fridge and the extractor and the coffee grinder might all be running together with the coffee machine boiler heating, count all of them.
- Add the single biggest start-up surge (usually a fridge compressor or extractor motor) on top of the running total. Only the biggest single surge — they don’t all kick in at the same instant.
- Multiply by 1.5 for safe headroom. This covers cold-morning starts, the cumulative drift of cheap appliances drawing slightly more than nameplate, and gives you a sensible operating margin so the generator isn’t running flat-out all shift.
- Round up to the next generator size. Don’t try to land exactly on the number — generators come in discrete kW bands (3, 5, 7, 8, 10, 12), so pick the next one up.
Worked example one — mobile coffee trailer
Fracino CON2ELPG in LPG mode (350 W) + grinder running on and off (400 W when grinding) + Atlantis Mini Gas LPG water boiler controls (50 W) + LED lights (80 W) + card reader and till (100 W) + a small under-counter fridge (240 W average). Running total: 1,220 W. Biggest surge: fridge at 720 W. So the worst-case moment is 1,940 W. Multiply by 1.5 for headroom: 2,910 W. The Greengear GE-3000UK at 2.8 kW rated / 3.1 kW peak fits exactly. Don’t go smaller.
Worked example two — burger van
Twin-pan LPG fryer (150 W controls) + LPG griddle (40 W) + LPG bain marie (60 W) + extractor fan (300 W) + commercial under-counter fridge (240 W average) + freezer (180 W average) + LED lights (100 W) + card reader and till (100 W). Running total: 1,170 W. Biggest surge: extractor at 900 W. Worst case: 2,070 W. Multiply by 1.5: 3,105 W. The GE-3000UK would technically just cover this, but with no margin for adding a coffee machine later or running a hot plate — sensible move is to step up to the GE-5000UK at 5.0 kW rated, which leaves you room to grow.
Worked example three — large event hog roast and bar
LPG hog roast oven (100 W controls) + LPG griddle (40 W) + twin commercial fridges (480 W average) + drinks chest freezer (180 W average) + commercial extractor (400 W) + festoon lighting (200 W) + PA system (250 W) + EPOS x2 (160 W) + phone chargers and Wi-Fi (60 W). Running total: 1,870 W. Biggest surge: extractor at 900 W. Worst case: 2,770 W. Multiply by 1.5: 4,155 W. The GE-5000UK covers this, but if you want a second coffee machine, an electric kettle for staff brews, or any redundancy at all, the GE-7000UK at 7.0 kW rated is the safer choice for events where you can’t afford a single trip.
Best LPG Generators for Mobile Catering by kW Band
3 kW band — Greengear GE-3000UK
The starter generator for mobile coffee trailers and small ice-cream vans. Pure LPG/propane (no petrol changeover), 212 cc OHV single-cylinder engine, 2.8 kW rated output and 3.1 kW peak. Electric start (with recoil backup) and a 110/230 V outlet pair makes it useful on both UK mains and site distribution boards. At 49 kg it’s the only generator in this guide that one person can comfortably lift in and out of a van. Use case: any coffee trailer running a Fracino CON2ELPG or similar dual-fuel espresso machine in LPG mode. Verified specs from the Greengear Global manual: 11.5 A rated current, 0.6 L oil capacity, 605 × 445 × 420 mm. From £1,495.
5 kW band — Greengear GE-5000UK or GearGB GCE5000B
The sweet spot for most UK burger vans, crepe trailers, and small street-food setups. Two routes here. The Greengear GE-5000UK is pure LPG: 389 cc engine, 5.0 kW rated / 5.5 kW peak, 21.7 A, 115/230 V dual outlet, 93 kg. The GearGB GCE5000B is dual-fuel petrol/LPG with a Briggs & Stratton XR1450 engine and a Meccalte alternator, 4.2 kW continuous on LPG (5 kW peak), 88 kg, UK-built. Choose Greengear if you want the simplest single-fuel setup; choose GearGB if you’d rather have petrol as a backup for the day someone forgets to swap the cylinder. Both run on propane at standard mobile-catering propane regulator pressure. From £1,895.
7 to 8 kW band — Greengear GE-7000UK or GearGB GCE8000B
For fully-loaded trailers running coffee, food and fridges from a single generator at events. The Greengear GE-7000UK uses a 420 cc 9.0:1 OHV engine, 7.0 kW rated / 7.5 kW peak, 30 A, 110/230 V, electric start, 96 kg. The GearGB GCE8000B is dual-fuel with a Briggs & Stratton XR2100 engine, 6.2 kW continuous on LPG (8 kW peak), 119 kg, 230 V with separate 16 A and 32 A outlets — handy if you’re plugging the trailer’s distribution board straight in. From £2,395.
10 kVA and above — GearGB GCE12000VL Vanguard
For twin trailers, large hog-roast operations, or operators who want a single generator that will outlive three or four catering businesses. 12.5 kVA / 10 kW peak / 9 kW continuous, Vanguard V-twin 630 cc engine, 144 kg dry weight, fixed-speed industrial frame. LPG consumption at continuous output is roughly 3.6 kg/hour — budget accordingly. Wheel kit and AVR are optional extras worth specifying for any unit that’s going to move between sites. From £3,995.
Running Cost — What an LPG Generator Burns Per Hour
Real-world propane consumption depends on load, but the manufacturer figures are a fair starting point. A 5 kW dual-fuel GearGB at 75 % load burns 1.2 kg/hour of propane. An 8 kW unit at 75 % load burns 2 kg/hour. A 12.5 kVA Vanguard at continuous load burns 3.6 kg/hour. At a UK trade propane price of roughly £2.80 per kg (47 kg cylinder), that puts running cost between £3.40/hour for a small coffee trailer setup and £10/hour for a fully-loaded festival rig.
A 19 kg propane cylinder will run a 5 kW generator at typical mobile catering load for roughly 12 to 15 hours of trading. A 47 kg cylinder will give you a comfortable two-day weekend on an 8 kW unit. Always trade with at least one full spare cylinder on the trailer — running out of propane mid-service is a guaranteed afternoon-killer.
Common Sizing Mistakes Mobile Caterers Make
- Sizing off maximum output instead of rated output. The generator manual quotes both — only the rated figure is sustainable. Use it.
- Forgetting the inrush surge of motors and compressors. Fridge compressors and extractor motors pull three times their running wattage for a second or two. A generator sized exactly to running load will trip on every fridge cycle.
- Buying a 2 kW camping inverter for a commercial coffee machine. Those units are 110 V American-spec or honest about being non-commercial. They cannot start an espresso machine boiler reliably. Don’t be the trader at 7 a.m. trying to explain to customers why there’s no coffee.
- Using a domestic petrol generator instead of LPG. Petrol generators leave a petrol tank on a hot trailer, are noisier, smellier, more emissions-heavy, and not legal at most food-festival pitches. LPG is the standard for a reason — no spillage, no decay, lower noise, cleaner exhaust, longer engine life.
- Buying way over-size “just to be safe”. A 12 kVA Vanguard on a one-person coffee trailer is wasted money, wasted fuel, and a 144 kg lift you don’t need. Right-size with the 1.5x headroom rule and stop there.
- Not factoring in growth. If you’re starting with a coffee trailer and you know within a year you’ll add a panini grill or a small fridge, size for that now. Generators are expensive to upgrade halfway through a season.
Gas Safety and Compliance for LPG Generators
An LPG generator on a mobile catering pitch should be installed and maintained by a Gas Safe registered engineer with the LPG commercial endorsement (typically the CP44 mobile catering certificate). The propane cylinder should be in an external locker, the hose between cylinder and generator should be the orange medium-pressure type appropriate for the regulator on the unit, and the regulator itself should match what the generator manufacturer supplies. Greengear units come with their own dedicated LPG regulator — don’t substitute a standard 37 mbar appliance regulator, because the generator engine needs a different pressure range than your fryer.
A CP44 certificate is commonly expected by event organisers and councils before they’ll let you trade with an LPG generator on board. Renewal is annual. For a step-by-step on the wider gas safety side of mobile catering, see our LPG conversion guide for food vans, which covers cylinder lockers, regulators, hoses, and certificates in detail.
How to Choose — Decision Tree
- If you’re running only a coffee setup (espresso machine, grinder, water boiler, lights, card reader): Greengear GE-3000UK.
- If you’re running a food trailer with LPG cooking and a fridge or two: Greengear GE-5000UK or GearGB GCE5000B.
- If you’re running a fully-loaded mobile kitchen at busy events: Greengear GE-7000UK or GearGB GCE8000B.
- If you’re running two trailers or a large festival pitch: step up to the GearGB GCE12000VL Vanguard.
- If you’re still on a petrol generator: switch. LPG is cheaper to run, cleaner, quieter, and the only fuel most modern event organisers will accept.
Browse the full LPG generators range at MobCater for current pricing and stock, or pair your generator choice with the right setup using our mobile coffee business startup guide.
Frequently Asked Questions
What size LPG generator do I need for a mobile coffee trailer?
A 3 kW LPG generator like the Greengear GE-3000UK is the right size for most mobile coffee trailers running a Fracino CON2ELPG or similar dual-fuel espresso machine, a grinder, a water boiler, lights, and a card reader. Running load is typically 1.2 to 1.8 kW with the 1.5x headroom rule landing you at 2.7 to 2.9 kW. Step up to 5 kW only if you’re adding a commercial fridge or planning a panini grill.
Can I run a fryer and a coffee machine off one LPG generator?
Yes, as long as both are propane-fired and only drawing electricity for controls. A typical LPG fryer plus a Fracino CON2ELPG in LPG mode together draw under 600 W from the generator — the propane is doing the cooking. A 3 kW generator handles this easily. The picture changes if you switch the coffee machine to full-electric mode, which pulls 2.8 kW on its own and needs a 5 kW generator minimum.
Is an LPG generator quieter than a petrol generator?
Yes, typically by 5 to 10 dB at the same load. The Greengear GE-3000UK runs at roughly 65 dB at 7 m, the GE-7000UK at 70 dB, and the GearGB 8 kW units at 70 dB. Petrol generators of the same kW band sit 5 to 10 dB higher. For event pitches that have a noise limit (most do), an LPG inverter-style unit gives you headroom to operate without complaints.
How long will a 19 kg propane cylinder run an LPG generator?
At 75 % load on a 5 kW generator, a 19 kg propane cylinder runs roughly 16 hours of trading. On a 3 kW unit at similar load you’ll get 22 to 25 hours. On an 8 kW unit you’ll get around 10 to 11 hours. Always carry at least one full spare on the trailer — propane runs out fastest on the coldest morning, when the regulator is working hardest and the cylinder pressure is lowest.
Can I use butane instead of propane in an LPG generator?
No. Mobile catering generators are rated for propane only at the regulator pressure supplied with the unit. Butane fails to vaporise below roughly 2 °C, which makes it useless for UK outdoor trading from October through April. Every commercial LPG appliance — generators, fryers, coffee machines, water boilers — is set up for propane. Butane belongs on patio heaters and camping stoves, not mobile catering.
Do I need a CP44 certificate for an LPG generator on my trailer?
Most UK event organisers and many local authorities commonly expect a CP44 (mobile catering LPG installation safety certificate) covering all LPG appliances on the trailer, including the generator. The certificate should be issued by a Gas Safe registered engineer with the commercial LPG and mobile catering endorsement. Renewal is annual and typically costs £80 to £150 depending on how many appliances are inspected.
What’s the difference between rated output and maximum output on a generator?
Rated output (sometimes called continuous output) is what the alternator can deliver hour after hour without overheating. Maximum output is a short-burst figure used to absorb start-up surges from motors and compressors. Always size off rated output and treat the maximum figure as start-up headroom only. A generator quoted as 3.1 kW max and 2.8 kW rated is really a 2.8 kW unit — that’s the figure that matters for steady trading.
Are dual-fuel petrol/LPG generators a good idea for mobile catering?
Dual-fuel units like the GearGB GCE5000B and GCE8000B give you propane as the primary fuel with petrol as an emergency backup, which is useful if you’re trading remotely and could be caught out by a missed cylinder swap. The trade-off is having petrol on board — which some event organisers don’t allow, and which adds storage and safety considerations. For most operators, a propane-only Greengear unit is simpler. For operators who trade in remote festival pitches, dual-fuel earns its keep.