If you’ve ever stared at a 15kg LPG gas bottle and wondered whether you’re getting the best deal, you’re not alone. Prices vary wildly between brands, refill spots, and even regions. This guide lays out the real costs from official sources, how long the gas actually lasts, and what to watch for when buying or refilling.

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Typical capacity of a 15 kg LPG cylinder: approx. 27-29 litres ·
Average cost to refill a 15 kg bottle in the UK (2025): £25-£40 ·
Estimated burn time for a 15 kg propane bottle (medium cooker): 50-60 hours ·
Energy content of 15 kg propane: ≈ 197 kWh ·
Typical cost per kWh for LPG vs. petrol (car conversion): LPG 30-50% cheaper

Quick snapshot

1Confirmed facts
2What’s unclear
  • Exact refill prices vary by location and retailer; no single UK-wide list exists
  • Actual burn time depends heavily on appliance type and user behaviour; generic estimates are rough
3Timeline signal
4What’s next
  • More motorhome owners switching to refillable systems (Safefill, Gaslow) to cut long-term cost
  • Expect regional price gaps to narrow as online refill locators improve

The table below summarises the key specifications of a 15 kg LPG gas bottle.

Key specs of a 15 kg LPG gas bottle
Specification Value
Full weight of 15kg propane bottle approx. 25-30 kg (cylinder + gas) Practical Motorhome
Empty weight (tare) 10-15 kg Practical Motorhome
Standard connector POL fitting (propane), clip-on (butane) Practical Motorhome
Common regulator type 30 mbar (propane), 28 mbar (butane) Practical Motorhome
Propane density ~0.51-0.55 kg/L → 15 kg = 27-29 L Practical Motorhome
Butane density ~0.38-0.42 kg/L → 15 kg = 37-39 L Practical Motorhome
Energy content (propane 15 kg) ≈ 197 kWh Practical Motorhome
Energy content (butane 15 kg) ≈ 198 kWh Practical Motorhome
Typical burn time (medium cooking) 50-60 hours on a 3-4 kW burner Practical Motorhome
Bottle lifespan (before mandatory inspection) 10-20 years with annual checks Practical Motorhome (gas safety)

How much does a 15 kg Calor gas cost?

The price depends on whether you buy a new full cylinder or just a refill, and which brand you choose. Calor and Flogas dominate the UK market, but independent outlets and B&Q offer alternatives.

Refill vs new full cylinder price

“Calor 15kg Butane refill: £56.50 inc. VAT per bottle” — Calor Gas official price list

Price comparison: Calor, Flogas, B&Q

Four suppliers, one pattern: Calor charges a premium for the brand, while Flogas through B&Q is cheaper on refills — but you may need to buy a cylinder first.

Supplier / Outlet Size New cylinder Refill price
Calor 15 kg Butane £106.49 £56.50
Calor 13 kg Propane £115.49 £45.50
Flogas (at B&Q) 13 kg Propane £86.00 (agreement) £38.00
Independent agricultural supplier 13 kg LPG ~£47.82 ~£28.27

The implication: shopping around can save you £15-£30 per refill compared to sticking with Calor.

The trade-off

Calor’s wide network means you can exchange bottles almost anywhere, but you pay for convenience. Flogas at B&Q is cheaper but requires returning to the same chain. For high-volume users, the savings add up fast.

The pattern: convenience costs about £18.50 per refill compared to the cheapest option.

How long does a 15 kg gas bottle last?

Runtime depends on what you’re powering. A 15 kg propane cylinder gives roughly 50-60 hours of continuous medium cooking on a typical hob. For a patio heater on high, expect about 0.7-1.0 kg per hour.

Usage duration for cooking, heating, and BBQ

  • Medium stove (3-4 kW): 15 kg lasts 50-60 hours Practical Motorhome (usage estimates)
  • Patio heater (high 12 kW): 1 kg/hour → about 15 hours on a full bottle
  • Caravan space heater (2-3 kW): 0.2-0.3 kg/hour, so 50-75 hours
  • BBQ (medium grilling): 0.3-0.5 kg/hour → 30-50 hours

Factors affecting burn time

  • Ambient temperature: cold weather increases consumption as gas doesn’t vaporise as efficiently
  • Regulator setting: a 30 mbar regulator delivers more gas than 28 mbar
  • Appliance efficiency: modern condensing heaters vs old radiant burners
  • User behaviour: frequent lid-lifting on a BBQ wastes gas

The catch: published burn times are optimistic lab numbers. Real-world usage can be 20-30% shorter, especially in windy or cold conditions.

How many litres of LPG are in a 15 kg cylinder?

The volume depends on the gas type because propane and butane have different densities. A 15 kg propane cylinder holds about 27-29 litres, while the same weight of butane fills 37-39 litres.

Propane and butane density differences

  • Propane density: 0.51-0.55 kg/L → 15 kg = 27.3-29.4 L
  • Butane density: 0.38-0.42 kg/L → 15 kg = 35.7-39.5 L

Unit conversions: kg to litres, kWh, m³

The table below shows how 15 kg of each gas translates into other common units.

Gas type Weight Litres Energy (kWh) Volume as gas (m³)
Propane 15 kg 27-29 L ≈ 197 kWh ≈ 7.5 m³
Butane 15 kg 37-39 L ≈ 198 kWh ≈ 6.5 m³

Why this matters: when comparing energy cost, calculate per kWh. At £56.50 for 197 kWh, Calor 15 kg butane works out to about 28.7p/kWh – nearly double the domestic electricity rate Calor Gas (official price).

The upshot

If you’re a motorhome owner or caravan user, switching from Calor to a refillable system like Safefill (initial cost £158-£165) can slash your per-kWh cost to about 10p, because you pay only for the gas at autogas rates (~64p per litre) Practical Motorhome (autogas refill advantage).

The pattern: refillable systems cut the running cost by roughly two-thirds compared to exchange bottles.

Is LPG cheaper to run than petrol?

For vehicle use, LPG is significantly cheaper per mile – typically 30-50% less than petrol at current UK pump prices. But there are upfront and practical trade-offs.

Cost per kWh comparison

  • LPG at 64.2p per litre (autogas) = ~10p/kWh Practical Motorhome (autogas price comparison)
  • Petrol at £1.40/litre ≈ 15p/kWh (based on energy density 9.5 kWh/litre)
  • LPG is 30-50% cheaper per mile

“LPG is 30-50% cheaper per mile than petrol” — Drive LPG cost analysis

Vehicle conversion costs and savings

  • Professional LPG conversion: £800-£2,000
  • Payback period for high-mileage drivers (12,000+ miles/year): 1-2 years
  • Lower CO₂ emissions, but 20-30% reduced range per tank

The pattern: for frequent drivers, conversion pays for itself quickly – but you need access to LPG filling stations, which are less common than petrol stations.

What to watch

Not all petrol stations carry autogas. The UK had about 1,400 LPG filling points in 2025, so route planning is essential. Motorhome owners often prefer refillable bottles they can swap at camping shops instead.

The implication: LPG vehicle conversion works best for drivers with predictable routes near autogas stations.

What are the disadvantages of using LPG?

LPG has safety and convenience drawbacks that every user should understand before committing.

Safety concerns and storage requirements

  • LPG is heavier than air – leaks accumulate in low spaces (basements, bilges), posing an explosion risk HSE (gas safety guidance)
  • Cylinders must be stored upright, outdoors, away from heat sources and drains
  • Transport in a closed car boot is restricted – best practice is open ventilation

Energy density and supply issues

  • LPG has lower energy density than petrol per litre – you need more frequent refills
  • Supply can be patchy in remote areas; not all retailers stock the right connector type
  • Bottled LPG costs more per kWh than mains natural gas (28p vs ~7p/kWh)

The trade-off: LPG is a good off-grid fuel, but you pay for portability and safety compliance.

How can I save money on LPG?

Every pound counts, especially if you use gas for heating or cooking year-round. Here are the proven strategies.

Buying in bulk vs single bottles

  • 47 kg bulk cylinder costs roughly £85-£100 vs £106 for four 13 kg Calor cylinders – cheaper per kg
  • Shared ownership schemes (e.g., with neighbours) on bulk tanks can cut cost by 30%

Efficient appliance use and maintenance

  • Regular servicing of gas appliances prevents wasteful consumption
  • Use a regulator with a thermostatic valve that adjusts flow
  • Insulate hot water pipes and use lids on pots

What this means: a £50 annual service on your heater can save £80 in wasted gas – a clear win.

Summary

For UK buyers, the 15 kg LPG gas bottle market is a tale of two prices. Pay £56.50 for a Calor refill because you value the national exchange network, or seek out a Flogas/B&Q refill at £38 — a saving of £18.50 per swap. If you use gas heavily, a refillable system like Safefill or Gaslow slashes the running cost to about 10p/kWh. For motorhome owners in the UK, the choice is clear: switch to refillable if you can afford the upfront cost and have access to autogas, or stick with exchange bottles and shop around aggressively.

Additional sources

flogas.co.uk

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Frequently asked questions

Can I use a 15kg LPG bottle indoors?

No. LPG cylinders must be used outdoors or in well-ventilated areas. Using them indoors poses a serious risk of gas accumulation and explosion. Always follow HSE safety guidelines.

How do I check if my 15kg gas bottle is empty?

You can weigh the bottle (full weight ~25-30 kg, empty ~10-15 kg) or pour warm water down the side – the level where the gas is will feel cold to the touch.

What is the difference between propane and butane in a 15kg bottle?

Propane (blue bottle) works in cold weather down to -42°C and has a different regulator (30 mbar). Butane (red) stops vaporising below 0°C and uses a 28 mbar regulator. Propane is more versatile for outdoor winter use.

Where can I refill a 15kg LPG gas bottle near me?

Check Calor’s dealer finder, B&Q’s Flogas exchange, or local agricultural suppliers. Autogas stations (for refillable bottles) can be found on the UKLPG website.

Are all 15kg gas bottle regulators the same?

No. Propane uses a 30 mbar regulator (POL fitting), butane uses 28 mbar (clip-on). Using the wrong regulator can cause unsafe gas pressure. Always match regulator to gas type.

Can I transport a 15kg LPG bottle in a car?

Yes, but with strict precautions: keep it upright, secure it from rolling, ventilate the area, and never carry in a closed boot. Some insurers have additional restrictions – check your policy.

How often do I need to maintain a 15kg gas cylinder?

Bottles must be visually inspected annually for rust, dents, or valve damage. They require a full requalification test every 10-20 years. If you see any damage, do not use and contact your supplier.

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