275 gallon oil tank: what it is and what it holds
A 275 gallon oil tank is the standard home heating oil tank: a steel oval 27 inches wide, 44 inches tall and 60 inches long, upright or on its side. The shell computes to about 274 gallons, and a fill into a near empty one runs 230 to 250 gallons. Nominal size, computed full and realistic fill are three different numbers.
What a 275 gallon oil tank measures
There is one shell and two ways to set it. Upright, the oval face points at you and the tank is tall and narrow. On its side, the same tank is wide and low, which is how it fits under a crawl space or a low basement ceiling. The length does not change. The width and the height trade places, and so does the depth you stick.
| Orientation | Dimensions (inches) | Stick depth | On the plate | Computed full |
|---|---|---|---|---|
| Upright (vertical) | 27 wide × 44 tall × 60 long | 44″ | 275 gallons | about 274 gallons |
| On its side (horizontal) | 44 wide × 27 tall × 60 long | 27″ | 275 gallons | about 274 gallons |
Dimensions and the plate rating match Granby's published model table for its standard UL 80 residential tanks, the same figures behind the Granby tank sizes page here. Computed full is the geometric volume of that shell at 231 cubic inches per gallon with a dished-head allowance, so it is a shell number and not a delivery figure. Empty weight below is Granby's listed weight for its own tank.
Granby lists the 275 at 250 pounds empty in 12 gauge steel, and also builds a heavier 10 gauge version. That is the bare tank with nothing in it, which is why nobody moves one until it has been drained. Measure your doorway and your stair turn before a swap day, not on it. Steel thickness, listed weights and every other standard size sit together on oil tank sizes and dimensions.
The three capacity numbers
A 275 has three capacities, and people trip over the gap between them constantly. They are not in conflict. They measure different things.
- 275 gallons nominal. The number on the data plate and in the catalog. It is the tank's name, rounded up from the shell.
- About 274 gallons computed full. The volume of the shell itself, top to bottom, dished ends included. This is the number the charts on this site run to, and it is the same in both orientations because it is the same shell.
- 230 to 250 gallons in a real fill. What goes into a near empty tank before the vent whistle stops the driver, with an air gap still at the top. A few more gallons sit below the outlet where the burner cannot draw them.
So a tank sold as a 275 gives you roughly 240 gallons of usable oil when it is called full, and that is normal rather than a short delivery. Why a 275 holds about 240 lays the numbers out side by side. If your ticket keeps reading 250 and you have started calling the tank a 250, that is the same arithmetic looked at from the other end.
Reading the level on a 275
The gauge on top gives you a fraction, not a number worth ordering on. For gallons, dip the tank with a clean stick through the fill or gauge opening, read the wet line in inches, and convert. How to stick an oil tank walks the whole job.
Which chart you read depends on how the tank sits, because the stick depth is different: 44 inches upright, 27 inches on its side. Use the 275 gallon oil tank chart (vertical) for an upright tank, and the 275 gallon oil tank chart (horizontal) for one lying down. It matters: 20 inches of oil is 123 gallons in the upright tank and 211 in the same tank on its side, because the shape under the wet line is not the same.
The float gauge is matched to that depth too, so an upright 275 and the same tank on its side take different parts. What each kind of gauge reads, and which one fits yours, is on oil tank gauge types.
- Upright, 44″ deep: a vertical float gauge built for that depth (Beckett vertical gauge on Amazon)
- On its side, 27″ deep: the horizontal gauge, a different part (Beckett horizontal gauge on Amazon)
How long a 275 lasts
There is no service life stamped on the size. Two tanks built in the same plant in the same year can be decades apart, and what separates them is water, not steel. Condensation settles under the oil, corrosion starts at the bottom of the shell and works outward, and the tank weeps from the inside. That is why chalky paint and surface rust outside often mean nothing, while a damp bottom seam means a great deal.
How long do oil tanks last covers the failure modes in order and the signs to watch for, and water in your oil tank covers how the water gets in and how to get it out. Condensation is worst in the air space of a half empty tank over the summer, so leaving a 275 reasonably full through the off season gives it less bare steel to form on.
Replacing a 275: what drives the price
Swapping an aboveground 275 is usually a one day job. The tank itself moves the bill less than the work around it, which is why two quotes on the same house can look so different.
- Getting the old one out. A tank at the bottom of a narrow stair is a different job from one beside a walkout door. An old tank that has to be drained, cut and carried out in pieces is different again.
- What goes back in. A standard single wall steel 275, or a double wall tank. Double wall costs more up front, and some towns treat it differently; ask yours before you choose.
- Where it sits. Indoors on a floor, or outdoors on a pad with weather protection.
- What your town wants. Permits and inspections vary by town, and so does what is required of the old tank.
Planning ranges, and what each of those choices does to them, are on oil tank replacement cost. If the old tank is buried, or you want it gone rather than replaced, see oil tank removal and disposal. Get two or three local quotes before you budget: this is priced on your house, not on a national average. And if you are not sure a 275 is still the right size, the what size tank do I need calculator works it from your yearly gallons.
Common questions
What does it cost to replace a 275 gallon oil tank?
It is usually a one day job, and the tank is the smaller part of the bill. The price is driven by getting the old tank out, whether the new one is single wall steel or double wall, where it sits, and what your town requires for permits and inspections. Oil tank replacement cost has the planning ranges, and two or three local quotes will beat any figure you read online.
What is the life expectancy of a 275 gallon oil tank?
There is no fixed number, and the size has nothing to do with it. Tanks built in the same plant in the same year can be decades apart, because what ends a tank is water sitting under the oil and corroding the shell from the inside out. Outside rust is usually cosmetic. How long do oil tanks last covers the failure modes and the warning signs.
How many gallons does a 275 gallon tank actually hold?
The shell computes to about 274 gallons, which is what the charts run to. A delivery into a near empty tank is 230 to 250 gallons, because the vent whistle stops the driver with an air gap still at the top, and a few gallons sit below the outlet out of the burner's reach. Why a 275 holds about 240 puts the three numbers side by side.
What are the dimensions of a 275 gallon oil tank?
Upright it is 27 inches wide across the oval, 44 inches tall and 60 inches long. On its side it is the same shell turned over: 44 inches wide, 27 inches tall, 60 inches long. The stick depth turns with it, 44 inches upright and 27 lying down, which is why the two read on different charts. Every standard size is listed on oil tank sizes and dimensions.
Is a 275 gallon tank big enough for my house?
It is the size most oil heated homes run, and it is what most swaps go back to. How many fills you need in a winter depends on the house, the equipment and the weather, so size a replacement from your own yearly gallons rather than from a rule of thumb. The what size tank do I need calculator does that arithmetic.
Disclosure: links to Amazon on this page are affiliate links. As an Amazon Associate this site earns from qualifying purchases, at no extra cost to you. It does not change what is recommended here, and no product on this page has been tested by us; the specifications are quoted from the manufacturers.
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