Oil Tank Sizes: What Size Do You Need?
Domestic heating oil tanks usually range from about 1,000 to 2,500 litres. Here’s how the common sizes and shapes compare, and how to pick the right one for your home.
The short answer
Most homes use a tank between 1,000 and 2,500 litres. Choose a size that holds at least a few months of your normal use plus a full minimum delivery from your oil supplier, and that fits your space while meeting the siting rules. Above 2,500 litres, a domestic tank must be bunded.
Common domestic oil tank sizes
Tank capacities vary by manufacturer and model, but most domestic tanks fall into a handful of size bands:
| Size band | Typically suits |
|---|---|
| Around 1,000 litres | Smaller homes and flats with lower heating demand, or sites with very limited space |
| 1,200 to 1,400 litres | The most popular band for typical family homes |
| 1,800 to 2,000 litres | Larger homes, older or less insulated properties, and households that want fewer deliveries |
| Around 2,500 litres | Large or rural properties with high demand. This is the largest size before bunding becomes mandatory for every home |
Oil tank shapes
The same capacity can come in different shapes to suit different spaces:
Horizontal tanks
The most common shape. They’re low and wide, sit well in an open garden or yard and are easy to inspect and fill.
Vertical tanks
Taller and with a smaller footprint, so they suit corners or small yards where floor space is tight but height isn’t a problem.
Slimline tanks
Long and narrow, designed to run along a wall, fence or side passage. They’re often the answer for terraced and semi-detached homes. See our slimline oil tanks.
Low profile tanks
Shorter tanks that sit below a window line or a low fence, so they’re less visible and easier to screen.
How to work out what size oil tank you need
1. Check how much oil you use
Add up your deliveries over the last 12 months from your supplier’s invoices. That’s your annual use, and it’s far more reliable than any rule of thumb based on the number of bedrooms. Usage depends on insulation, the age of your boiler, whether oil heats your hot water too, and how warm you keep your home.
2. Think about deliveries
Most suppliers have a minimum order, and larger orders often cost less per litre. Your tank needs room for a full minimum delivery even when it isn’t empty. A larger tank lets you fill up when prices are low and order less often, which helps in winter when delivery times get longer.
3. Measure your space
Measure the area where the tank will go, then allow for the base. The base must extend at least 300 mm beyond the tank on every side. Check access too, because the tank has to be carried or lifted into place.
4. Check the siting rules
A standard tank should be at least 1.8 m from non-fire-rated buildings, eaves and structures such as sheds, 1.8 m from doors, windows and flue terminals, and 760 mm from non-fire-rated boundaries such as wooden fences. If a larger tank won’t fit those distances, a smaller tank, a slimline shape or a fire protected tank may work. Read our OFTEC regulations guide for the full rules.
5. Remember the 2,500 litre threshold
Any domestic tank holding more than 2,500 litres must be bunded. Smaller tanks often need bunding too, depending on the site. See do I need a bunded oil tank?
Bunded and slimline tanks we supply, by size
Real dimensions from the tanks in our range, smallest first. Capacities marked “brimful” are the volume when filled to the top.
| Tank | Capacity | Length / diameter | Width | Height |
|---|---|---|---|---|
| 650 Litre Slimline Bunded Oil Tank | 673 litres (brimful) | 1,715 mm | 670 mm | 1,330 mm |
| 1000 Litre Slimline Bunded Oil Tank (1000 SSL) | 999 litres (brimful) | 1,900 mm | 640 mm | 1,465 mm |
| 1000 Litre Slimline Bunded Oil Tank | 1,055 litres (brimful) | 2,150 mm | 690 mm | 1,420 mm |
| 1100 Litre Slimline Bunded Oil Tank | 1,097 litres (brimful) | 1,880 mm | 890 mm | 1,595 mm |
| 1225 Litre Slimline Bunded Oil Tank | 1,248 litres (brimful) | 2,110 mm | 840 mm | 1,525 mm |
| 1200 Litre Low Profile Bunded Oil Tank | 1,317 litres (brimful) | 1,900 mm | 1,600 mm | 960 mm |
| 1300 Litre Slimline Bunded Oil Tank | 1,344 litres (brimful) | 2,100 mm | 950 mm | 1,540 mm |
| 1400 Litre Slimline Bunded Oil Tank (1400 SSL) | 1,435 litres (brimful) | 2,110 mm | 640 mm | 1,670 mm |
| 1400 Litre Horizontal Bunded Oil Tank | 1,452 litres (brimful) | 1,900 mm | 1,250 mm | 1,420 mm |
| 1450 Litre Vertical Bunded Oil Tank | 1,498 litres (brimful) | Ø 1,560 mm | – | 1,590 mm |
| 1650 Litre Horizontal Bunded Oil Tank (1650 HZB) | 1,662 litres (brimful) | 2,010 mm | 1,350 mm | 1,430 mm |
| 2000 Litre Horizontal Bunded Oil Tank | 2,092 litres (brimful) | 2,360 mm | 1,315 mm | 1,415 mm |
| 2500 Litre Horizontal Bunded Oil Tank | 2,571 litres (brimful) | 2,460 mm | 1,435 mm | 1,470 mm |
| 3500 Litre Horizontal Bunded Oil Tank | 3,471 litres (brimful) | 2,450 mm | 1,770 mm | 1,890 mm |
| 5400 Litre Vertical Bunded Oil Tank | 5,307 litres (brimful) | Ø 2,575 mm | – | 2,100 mm |
| 7500 Litre Vertical Bunded Oil Tank | 8,088 litres (brimful) | 2,940 mm | 2,305 mm | 2,820 mm |
| 9250 Litre Vertical Bunded Oil Tank | 9,382 litres (brimful) | 3,140 mm | 2,510 mm | 2,820 mm |
Replacing a tank? Don’t just match the old size
When an old tank is replaced, it’s worth checking whether the old size still suits you. Many older tanks were sited closer to buildings and boundaries than current rules allow, so the new tank may need a different position or shape. During a free site survey, we measure the space, check the siting distances and bunding requirements, and recommend a size based on your actual use. Find out more about our oil tank replacement service.
Frequently asked questions
What size oil tank do I need for a three-bedroom house?
Many three-bedroom homes use a tank of around 1,200 to 1,400 litres, but the right size depends on how much oil you actually burn. Check your last year of delivery receipts and choose a tank that holds at least a few months’ supply, with room for a full minimum delivery.
Can I replace my oil tank with a bigger one?
Yes, as long as there’s space for the larger tank and its base while still meeting the siting distances. A tank over 2,500 litres serving a home must be bunded, and a bigger tank may need a larger concrete base.
What is the difference between nominal and brimful capacity?
Nominal capacity is the usable volume a tank is sold as. Brimful capacity is the volume if it were filled to the very top, which is always a little higher. Plan your deliveries around the nominal figure.
Is a slimline oil tank smaller?
Not necessarily. Slimline tanks are narrower and taller or longer, so they can hold a similar volume to a standard horizontal tank while fitting along a wall or down a side passage.
Not sure which size is right?
Our OFTEC registered technicians cover Lincolnshire, Nottinghamshire, Yorkshire and Rutland. Call 01673 572222 or send a few details for free, no-obligation advice.
More advice: all oil tank guides