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Campervan Fuel Cost Per Mile (2026): Formula and Examples

Last updated: 27 October 2026 · Kervana team

Short answer

At the UK average diesel price in October 2026 (about 199p a litre), a campervan or motorhome doing 28 mpg costs about 32p a mile in fuel. A lighter van conversion at 35 mpg costs about 26p a mile; a heavy motorhome at 22–25 mpg costs 36–41p.

That means 100 miles costs roughly £28–36 for most vans and motorhomes, and a 1,000-mile month on the road around £280–360 in diesel.

The formula

UK mpg uses the imperial gallon, which is 4.546 litres. To turn a pump price into a cost per mile:

Cost per mile (pence) = price per litre (pence) × 4.546 ÷ your mpg

Example: 199.3p × 4.546 ÷ 28 mpg = 32.4p a mile.

Two more conversions that come in handy:

  • Per kilometre: divide the cost per mile by 1.609. At 28 mpg that is about 20p per km.
  • L/100 km to mpg: 282.5 ÷ L/100 km. A van doing 10 L/100 km returns about 28 mpg.

Cost per mile by mpg (diesel, October 2026)

Based on the UK average of 199.33p a litre for diesel (week of 19 October 2026), which is about £9.06 a gallon.

Fuel economyL/100 kmCost per mileCost per kmMiles per £1
22 mpg12.841.2p25.6p2.4
25 mpg11.336.2p22.5p2.8
28 mpg10.132.4p20.1p3.1
30 mpg9.430.2p18.8p3.3
32 mpg8.828.3p17.6p3.5
35 mpg8.125.9p16.1p3.9

Petrol is cheaper per litre (174.57p in the same week, about £7.94 a gallon), so a petrol van at 30 mpg costs about 26.5p a mile. Most campervans and motorhomes in the UK run on diesel.

What mpg does a campervan really get?

Owner-reported figures are more useful than official ones, because a loaded van with bikes on the back rarely matches the brochure.

  • Van conversions (up to about 6 m): usually 30–35 mpg. Owners of the popular Fiat Ducato base report an average of about 31 mpg across engines; the 2.2-litre versions often reach 35–36 mpg.
  • Coachbuilt motorhomes around 6 m and 3,500 kg: about 28–32 mpg in owners' reports.
  • Larger motorhomes over 6 m and 3,500 kg: around 25 mpg, and less when heavily loaded.

Speed, load, wind and hills move these figures more than the badge on the engine. If you don't know your own mpg yet, start with 28 mpg for a motorhome and 32 mpg for a van conversion, then measure it (below).

Examples

At 199.33p a litre:

Trip25 mpg28 mpg32 mpg
100 miles£36.25£32.36£28.32
300 km (186 miles)£67.57£60.33£52.79
1,000 miles£362.47£323.63£283.18

A full 80-litre tank of diesel costs about £159 at the same price.

How to measure your own cost per mile

The dashboard figure is often optimistic. The fill-to-fill method is more reliable:

  1. Fill the tank to the brim and note the odometer reading.
  2. Drive as normal. At the next fill, fill to the brim again and note the litres and the new odometer reading.
  3. mpg = miles driven ÷ (litres ÷ 4.546). Cost per mile = what you paid ÷ miles driven.

Example: 412 miles on 63.4 litres is 29.5 mpg. At 199.3p a litre the fill cost £126.38, or 30.7p a mile.

Do it over three or four fills and take the average; a single tank can be skewed by a windy motorway day or a week parked up.

What pushes the cost up

  • Speed: a tall, boxy vehicle uses noticeably more fuel at 70 mph than at 60 mph.
  • Weight: full water tanks, bikes, a roof box and everything "just in case" add up.
  • Tyre pressure: under-inflated tyres raise consumption; check them cold, to the pressures for a loaded vehicle.
  • Short hops and idling: a cold engine and running the engine to charge batteries or heat the van cost fuel without moving you.

Plan a trip, then track it

  1. Put your route into the trip cost calculator: distance in miles, your mpg and the fuel price. It adds campsites, food and tolls and shows the total, daily and per-mile cost.
  2. On the road, log each fill-up with the litres (or gallons) and the odometer reading. Kervana works out your average mpg and the cost per mile of each trip, and shows plan and actual side by side.

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Sources

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