Diesel Cost Per Mile in the UK: Formula and Table

A diesel van doing 36 mpg costs 25.2p a mile in fuel. That uses the Department for Energy Security and Net Zero (DESNZ) average diesel price of 199.22p a litre for the week of 26 October 2026. Multiply the pence per litre by 4.54609, then divide by your miles per gallon.

How do you work out diesel cost per mile?

You work out diesel cost per mile by turning the price of a litre into the price of a gallon, then dividing by the miles you get from that gallon. The formula is:

Pence per mile = pence per litre x 4.54609 / mpg

UK miles per gallon are imperial gallons, and one imperial gallon is 4.54609 litres. At 199.22p a litre, a gallon of diesel costs about £9.06. A van that covers 36 miles on that gallon is paying 25.2p for each mile.

If you do not know your mpg, measure it. Fill the tank, note the odometer, drive as normal, fill again and record the litres. Divide the miles driven by the litres, then multiply by 4.54609 to get miles per gallon. Do it over several fills, because one tank can be misleading.

The pump price includes tax. In the week of 26 October 2026 DESNZ shows fuel duty at 52.95p a litre and VAT at 20%. If your business reclaims VAT on fuel, use the pump price divided by 1.2 instead, and say so in any figures you pass to finance.

What is the diesel cost per mile at different mpg?

At the week of 26 October 2026 price, diesel costs between 18.1p and 30.2p a mile across the range of 50 to 30 mpg. The table uses DESNZ’s weekly road fuel prices: 199.22p a litre for that week, and 142.38p for the week of 27 October 2025.

Miles per gallon	Cost per mile, week of 26 Oct 2026	Cost per mile, week of 27 Oct 2025	Increase
30 mpg	30.2p	21.6p	8.6p
36 mpg	25.2p	18.0p	7.2p
40 mpg	22.6p	16.2p	6.4p
45 mpg	20.1p	14.4p	5.7p
50 mpg	18.1p	12.9p	5.2p

Source: DESNZ, weekly road fuel prices, diesel, UK average. Figures rounded to 0.1p.

Read across the row that matches your vehicle. A loaded long-wheelbase panel van can sit near the bottom of the mpg range. A lightly loaded small van on steady roads can sit near the top.

How much has the diesel cost per mile moved in a year?

Diesel cost per mile has risen by about 40% in twelve months. DESNZ recorded 142.38p a litre in the week of 27 October 2025 and 199.22p in the week of 26 October 2026, a rise of 56.84p a litre.

The year was not a steady climb:

• Early 2026 low: 140.72p a litre in the week of 9 February 2026, the lowest week of the past year. At 36 mpg that is 17.8p a mile.
• Spring jump: from 142.15p in the week of 2 March 2026 to 192.14p in the week of 13 April 2026. That is 50p a litre in six weeks.
• Summer dip: 164.52p in the week of 13 July 2026, or 20.8p a mile at 36 mpg.
• Autumn peak: 200.04p in the week of 12 October 2026, the highest week since the DESNZ series began in June 2003. At 36 mpg that is 25.3p a mile.

Fuel prices rise faster than most budgets are revised. A van doing 20,000 miles a year at 36 mpg burned about £3,600 of diesel at the price a year ago. At today’s price the same miles cost about £5,040. That is roughly £1,440 more per van, with no change in how the van is used.

Does diesel van cost per mile differ from a diesel car?

Yes, because the formula is the same but the mpg is different. Vans carry weight and have a larger frontal area, so they usually return fewer miles per gallon than a car.

HMRC publishes workings for its advisory fuel rates, and those show how mpg varies by engine size. For diesel company cars, HMRC’s mean mpg is 55.7 for 1,600cc or less, 49.6 for 1,601 to 2,000cc and 36.6 for over 2,000cc. At the week of 26 October 2026 price those work out at 16.3p, 18.3p and 24.7p a mile. The HMRC advisory fuel rates guidance sets the rates, which apply only to company cars and are reviewed each quarter.

For a van, use your own mpg, not a car figure. Our advisory fuel rates tool has the HMRC rates by quarter.

Why does speed change the number?

Speed changes the number because fuel use per mile climbs as average speed rises above the most economical speed. The Department for Transport’s fuel consumption curves (TAG data book v2.03, May 2026) put the diesel van’s most economical speed at about 39 to 40 mph, and show fuel per mile 14.5% lower at 60 mph than at 68 mph.

That is why your mpg is not a fixed property of the van. The same van at the same weight uses more fuel per mile on a fast motorway run than on a steadier one. We show how to apply the DfT figures to your own cost in what speed costs per mile.

Where can you see this week’s figure?

The live figure is on our fleet cost index, which updates every Tuesday after DESNZ publishes. It shows diesel, petrol and electric van cost per mile for the latest week, has a fleet calculator, and offers the weekly series back to June 2003 as a download.

To go from a pence-per-mile figure to a whole-fleet figure that includes maintenance, tyres, insurance and depreciation, read how to calculate fleet cost per mile. For the same maths with petrol, see petrol cost per mile. For the wider price story, see diesel above £2 a litre.

Frequently Asked Questions

What is the average diesel cost per mile in the UK?

There is no single average, because it depends on your mpg. At 36 mpg a diesel van costs 25.2p a mile using the DESNZ average diesel price of 199.22p a litre for the week of 26 October 2026. At 50 mpg it is 18.1p, and at 30 mpg it is 30.2p.

How do I calculate diesel cost per mile for a van?

Multiply the diesel price in pence per litre by 4.54609, then divide by the van’s miles per gallon. For 199.22p a litre and 36 mpg the answer is 25.2p a mile. Use your own mpg from several tanks of fuel rather than the manufacturer’s claim.

How much did diesel cost per mile a year ago?

At 36 mpg it was 18.0p a mile, based on DESNZ’s average of 142.38p a litre for the week of 27 October 2025. It is now 25.2p, an increase of 7.2p a mile or about 40%.

Does the diesel cost per mile include VAT?

Yes, if you use the pump price. DESNZ’s weekly figures include fuel duty of 52.95p a litre and 20% VAT. If your business reclaims VAT on fuel, divide the pump price by 1.2 before you use the formula.

Is cost per mile the same as the HMRC advisory fuel rate?

No. The HMRC rate is a set figure for company cars, 15p to 22p a mile for diesel from 1 September 2026, reviewed each quarter. Your actual diesel cost per mile depends on this week’s price and your vehicle’s mpg, so the two can differ.

Cut your fleet’s fuel bill

Your number is the one in the table that matches your van’s mpg. Check this week’s figure on the fleet cost index, then run your own miles through the speed and fuel tool.

A speed cap changes the number because it limits the fastest, thirstiest miles. The Department for Transport’s fuel consumption curves (TAG data book v2.03, May 2026, source) show a diesel van uses 14.5% less fuel per mile at 60 mph than at 68 mph. How much that saves your fleet depends on how many of your miles are driven above the cap.

AutoKontrol has made speed limiters in Britain since 1985, for vans, cars, HGVs and buses, installed nationwide: we come to you. If you want your own saving worked out, book a free consultation or get a quote. If you also want to track the fleet, TrackSpeed combines a speed limiter and GPS tracking in one device, one installation and one subscription.