How long does heating oil last?
A typical Irish home burns about 7.1 L of oil a day in January and under 1 litre a day in July. So 500 litres lasts about 2 months from the start of January, and many months if you fill up in June. Here is where those numbers come from, and how to get a figure for your own house.
Updated
How long does a fill of heating oil last in winter?
These are rough figures for three example homes. Each cell is how long the oil takes to burn, starting on 1 January, as the weather slowly warms into spring.
| Oil | Smaller home | Typical home | Larger home |
|---|---|---|---|
| 300 litres | About 65 days | About 45 days | About 25 days |
| 500 litres | About 4 months | About 2 months | About 45 days |
| 900 litres | Over 6 months | About 6 months | About 3 months |
| 1,000 litres | Over 6 months | Over 6 months | About 3 months |
The three homes are:
- Smaller home: 80 m², 1 person, oil for heating and hot water, average insulation, heating on morning and evening.
- Typical home: 120 m², 2 people (the planner's starting point), oil for heating and hot water, average insulation, heating on morning and evening.
- Larger home: 200 m², 4 people, oil for heating and hot water, average insulation, heating on morning and evening.
How long does heating oil last in summer?
Much longer. With the heating off, the boiler mostly heats water. Oil delivered on 1 June has to get through the summer and then into autumn, when use climbs again.
| Oil | Smaller home | Typical home | Larger home |
|---|---|---|---|
| 300 litres | Over 6 months | About 5 months | About 4 months |
| 500 litres | Over 6 months | Over 6 months | About 5 months |
| 900 litres | Over 6 months | Over 6 months | Over 6 months |
| 1,000 litres | Over 6 months | Over 6 months | Over 6 months |
"Over 6 months" means the oil outlasts the six-month window our model looks ahead. By then you are well into winter, so check the tank again in October either way.
How much heating oil does a house use a day?
| Home | January | April and October | July | Whole year |
|---|---|---|---|---|
| Smaller home | 4.7 L | 2.9 L | 0.5 L | About 1,000 L |
| Typical home | 7.1 L | 4.4 L | 0.8 L | About 1,500 L |
| Larger home | 11.8 L | 7.4 L | 1.3 L | About 2,550 L |
These are averages for normal weather. A cold snap pushes use up for as long as it lasts, which is why the planner also looks at the weather forecast for your area.
How we worked these out
These figures come from the same model that runs the Tankful tank planner, with no personal details entered beyond floor area and the number of people. In short:
- Heat loss is estimated from floor area and a broad insulation level. The colder it is outside, the more heat the house needs.
- Outdoor temperatures are 1991–2020 monthly averages from Met Éireann's Casement station, the nearest one in the model to Co. Westmeath.
- Hot water is a daily allowance for each person, all year round.
- Heat is turned into litres using SEAI's energy conversion factor for kerosene (35.36 MJ a litre, about 9.8 kWh), with an 85% efficient boiler.
Coastal counties, especially in the south-west, have milder winters, so the same home there burns a bit less. The planner adjusts for your county, and uses the actual weather forecast for the next week or so.
Can you use all the oil in the tank?
No, and you shouldn't try. Plan around less oil than the gauge shows, for two reasons.
First, the bottom of the tank isn't clean oil. Water and sludge settle there. If the level drops too low, or a delivery stirs it up, sludge can reach the boiler, block its filter and stop it. Certa, an Irish oil supplier, suggests reordering with at least a quarter of the tank left for this reason.
Second, you need time for a delivery. Certa also warns that winter demand is high and oil suppliers may take a while to reach you. The planner keeps a reserve of 15% of your tank, or 50 litres if that is more, and tells you to order before you reach it. On a 1,000 litre tank that is 150 litres.
So for a 1,000 litre tank filled to about 900 litres, think of it as roughly 750 litres of usable oil. For a typical home filled on 1 January, that is about 4 months before you should reorder, not 6 months.
The planner suggests topping up to about 90% of the tank, which is why we use 900 litres for a 1,000 litre tank. If you're not sure what your tank holds, see how to check your oil tank level.
Why your oil might run out faster than this
- An older or draughty house with a low BER rating.
- Heating on all day, or rooms kept above 20°C.
- More people at home, more showers and baths.
- An old boiler that hasn't been serviced. See what an oil boiler service costs.
- A leak. If you suddenly use far more oil than usual, or smell oil around the tank, read what to do if your oil tank is leaking.
For tips that actually cut use, see how to use less heating oil.
Work out your own figure
Your own deliveries tell you more than any table. Note the level on two dates, add any oil delivered in between, and divide the litres used by the number of days. Our guide to how much heating oil you need walks through it.
Common questions
How long does 500 litres of heating oil last?
For a typical Irish home of about 120 m² with two people, the Tankful planner's model says 500 litres filled on 1 January lasts about 2 months. Filled on 1 June it lasts over 6 months, because summer use is mostly hot water. Your own use could be half or double this.
How long does a 1,000 litre tank of oil last?
The planner suggests filling a 1,000 litre tank to about 90%, or 900 litres. For a typical home that lasts about 6 months from 1 January. But the planner holds back 150 litres as a reserve, so plan to reorder after about 750 litres, which is about 4 months in winter.
How much heating oil does a house use a day in winter?
The planner's starting estimate for a typical home is about 7.1 L a day in January, 4.4 L in April and October, and 0.8 L in July. A large, poorly insulated home with the heating on all day can use far more.
Can I use every last litre in the tank?
No. Water and sludge settle at the bottom of a tank. Running very low can pull that sludge into the filter and stop the boiler. Reorder while there is still a good margin left.
Get a date for your own tank
The Tankful tank planner takes your county, tank size and level, and the details of your home. It checks the weather forecast for your area and tells you the date to order by, with a range. You can add that date to your calendar or set a price alert so you know when to buy.