Heating Oil Calculator
Work out oil costs, litres per budget, annual spend and cost per kWh
Last updated: June 2026
Heating oil cost calculator
If your home is off the gas grid, heating oil (kerosene) is probably your biggest winter expense — and unlike mains gas and electricity it has no Ofgem price cap, so the price you pay swings with the global oil market and the time of year. This free heating oil calculator does three jobs in one: it works out the cost of an oil order from the litres and the price per litre, tells you how many litres a fixed budget will buy, and estimates your whole-year heating oil bill from your home size. It also converts the price into a cost per kilowatt-hour (kWh) so you can compare oil fairly against gas, electricity or a heat pump. It is built for the roughly 1.5 million UK households that heat with oil, whether you are placing a single tank fill, budgeting for the year, or deciding when to order. Everything runs in your browser — no postcode, no email, no sales calls.
How it works
The maths is simple and transparent:
- Order cost = litres × (price in pence ÷ 100). So 1,000 litres at 75p costs 1,000 × £0.75 = £750.
- Litres from a budget = budget ÷ price per litre in pounds. A £500 budget at 75p buys 500 ÷ 0.75 = 667 litres.
- Annual cost = estimated annual litres × price per litre. We use typical off-grid usage of about 1,100 L (small), 1,700 L (3-bed), 2,300 L (4-bed) or 3,200 L (5+ bed) per year, or you can type in your own figure.
- Cost per kWh = (price in pence ÷ 100) ÷ 10.35 × 100. One litre of kerosene contains about 10.35 kWh of energy (its gross calorific value), so at 75p/litre oil costs about 7.25p per kWh.
VAT note: domestic heating oil is charged the reduced 5% VAT rate. Quoted supplier prices usually already include VAT, so enter the price exactly as your supplier shows it.
Worked example
Imagine a 4-bedroom farmhouse that burns about 2,300 litres of kerosene a year, and today’s price is 75p per litre:
- Annual cost = 2,300 × £0.75 = £1,725 per year.
- Energy used = 2,300 × 10.35 = 23,805 kWh.
- Cost per kWh = 75p ÷ 10.35 = 7.25p per kWh.
- Deliveries = 2,300 ÷ 1,000 = about 2.3 fills of 1,000 litres a year.
If the price dropped to 65p/litre, the same household would pay 2,300 × £0.65 = £1,495 — a £230 saving, which is why ordering in summer when demand is low often pays off.
Frequently asked questions
How much does it cost to fill a heating oil tank?
It depends on the tank and the price. Most domestic deliveries are 500–1,000 litres. At a 2026 price of about 75p per litre, a 1,000-litre order costs around £750 and a 500-litre order about £375. Enter your own litres and price above for an exact figure.
How much heating oil does a house use per year?
A typical off-grid UK home uses roughly 1,100 litres (small), 1,700 litres (3-bed), 2,300 litres (4-bed) or 3,200+ litres (large/older) per year. Usage depends heavily on insulation, how warm you keep the house and how cold the winter is.
Is heating oil cheaper than gas or electricity?
At about 75p per litre, kerosene works out near 7.25p per kWh of heat — usually cheaper per unit than electricity and broadly comparable with mains gas, though oil prices are not capped and can move sharply. Use the cost-per-kWh figure this calculator gives you to compare directly.
Why is the price per litre cheaper for bigger orders?
Suppliers spread delivery costs over more litres, so the per-litre price usually falls as the order size rises — a 1,000-litre fill is normally cheaper per litre than 500 litres. It can pay to order with neighbours or join a local oil-buying club.
Source: Energy content of kerosene (gross calorific value ~10.35 kWh/litre) and the 5% reduced VAT rate on domestic fuel are long-standing UK figures; current market prices were checked against supplier trackers in 2026. See HMRC’s guidance on the reduced VAT rate for domestic fuel and power (gov.uk). Heating oil is unregulated, so always confirm today’s price with your supplier.