Heating Oil Tank Chart — Inches to Gallons
Measure the depth of oil in your tank with a dipstick, then read across this oil tank gallons chart to estimate how many gallons remain. The figures below are calculated heating-oil tank estimates based on standard nominal residential tank dimensions, covering the common heating oil tank sizes — 275, 330, 500, 550 and 1000-gallon tanks — in both vertical (upright) and horizontal (flat) configurations. The popular 275 gallon oil tank chart appears in both orientations below.
Calculated heating-oil tank estimates based on standard nominal residential tank dimensions. Actual tanks vary by manufacturer, installation, tilt, dents, fittings, unusable bottom volume, and fill-room practices.
How to read your tank with a stick
The most reliable way to check a heating oil tank is to measure the oil depth directly. Remove the cap or plug on top of the tank, lower a long, clean stick straight down until it touches the bottom, withdraw it, and read how many inches of the stick are wet with oil. Then find that depth in the chart below under your tank size. Make sure the stick is long enough that it cannot fall into the tank.
Float gauges built into the tank give only a rough indication and can stick or fail due to sludge, so a stick reading is more dependable. The number you get is an approximate estimate, not an exact measurement.
Tank dimensions used for these estimates
These 275 gallon oil tank dimensions and the other sizes below are typical residential values used to estimate oil tank capacity at each oil depth. A standard 275-gallon tank body is about 27 × 44 × 60 inches; vertical and horizontal versions use the same body in different orientations. Your tank's exact dimensions may differ.
| Tank | Cross-section dimensions | Length | Cross-section model | Typical fill |
|---|---|---|---|---|
| 275 gal horizontal (275H) | 27 × 44 in | 60 in | Obround (stadium) | ~250 gal |
| 275 gal vertical (275V) | 44 × 27 in | 60 in | Vertical linear | ~250 gal |
| 330 gal horizontal (330H) | 44 × 27 in | 72 in | Obround (stadium) | ~300 gal |
| 330 gal vertical (330V) | 27 × 44 in | 72 in | Vertical linear | ~300 gal |
| 500 gal cylinder | 48 in dia. | 65 in | Horizontal cylinder | ~450 gal |
| 550 gal cylinder | 48 in dia. | 72 in | Horizontal cylinder | ~500 gal |
| 1000 gal cylinder | 48 in dia. | 130 in | Horizontal cylinder | ~900 gal |
Oil depth to gallons chart (calculated estimates)
Find the oil depth in inches in the left column, then read across to your tank size. Values are approximate calculated estimates. Blank cells mean that depth is above the top of that tank.
| Depth (in) | 275H | 275V | 330H | 330V | 500 | 550 | 1000 |
|---|---|---|---|---|---|---|---|
| 1" | 6 | 6 | 8 | 8 | 3 | 3 | 5 |
| 2" | 14 | 13 | 17 | 15 | 7 | 8 | 14 |
| 3" | 23 | 19 | 27 | 23 | 13 | 14 | 26 |
| 4" | 32 | 25 | 39 | 30 | 20 | 22 | 40 |
| 5" | 42 | 31 | 51 | 38 | 28 | 30 | 55 |
| 6" | 52 | 38 | 63 | 45 | 36 | 40 | 72 |
| 7" | 63 | 44 | 76 | 53 | 45 | 50 | 90 |
| 8" | 74 | 50 | 89 | 60 | 55 | 60 | 110 |
| 9" | 85 | 56 | 102 | 68 | 65 | 71 | 130 |
| 10" | 97 | 63 | 116 | 75 | 75 | 83 | 151 |
| 11" | 108 | 69 | 130 | 83 | 86 | 95 | 173 |
| 12" | 120 | 75 | 144 | 90 | 98 | 108 | 196 |
| 13" | 132 | 81 | 158 | 98 | 109 | 120 | 219 |
| 14" | 143 | 88 | 172 | 105 | 121 | 133 | 243 |
| 15" | 155 | 94 | 186 | 113 | 133 | 147 | 267 |
| 16" | 167 | 100 | 200 | 120 | 146 | 160 | 292 |
| 17" | 178 | 106 | 214 | 128 | 158 | 174 | 317 |
| 18" | 190 | 113 | 228 | 135 | 171 | 188 | 343 |
| 19" | 201 | 119 | 241 | 143 | 184 | 203 | 368 |
| 20" | 212 | 125 | 254 | 150 | 197 | 217 | 394 |
| 21" | 223 | 131 | 267 | 158 | 210 | 231 | 421 |
| 22" | 233 | 138 | 279 | 165 | 224 | 246 | 447 |
| 23" | 243 | 144 | 291 | 173 | 237 | 260 | 473 |
| 24" | 252 | 150 | 303 | 180 | 250 | 275 | 500 |
| 25" | 261 | 156 | 313 | 188 | 263 | 290 | 527 |
| 26" | 269 | 163 | 322 | 195 | 276 | 304 | 553 |
| 27" | 275 | 169 | 330 | 203 | 290 | 319 | 579 |
| 28" | — | 175 | — | 210 | 303 | 333 | 606 |
| 29" | — | 181 | — | 218 | 316 | 347 | 632 |
| 30" | — | 188 | — | 225 | 329 | 362 | 657 |
| 31" | — | 194 | — | 233 | 342 | 376 | 683 |
| 32" | — | 200 | — | 240 | 354 | 390 | 708 |
| 33" | — | 206 | — | 248 | 367 | 403 | 733 |
| 34" | — | 213 | — | 255 | 379 | 417 | 757 |
| 35" | — | 219 | — | 263 | 391 | 430 | 781 |
| 36" | — | 225 | — | 270 | 402 | 442 | 804 |
| 37" | — | 231 | — | 278 | 414 | 455 | 827 |
| 38" | — | 238 | — | 285 | 425 | 467 | 849 |
| 39" | — | 244 | — | 293 | 435 | 479 | 870 |
| 40" | — | 250 | — | 300 | 445 | 490 | 890 |
| 41" | — | 256 | — | 308 | 455 | 500 | 910 |
| 42" | — | 263 | — | 315 | 464 | 510 | 928 |
| 43" | — | 269 | — | 323 | 472 | 520 | 945 |
| 44" | — | 275 | — | 330 | 480 | 528 | 960 |
| 45" | — | — | — | — | 487 | 536 | 974 |
| 46" | — | — | — | — | 493 | 542 | 986 |
| 47" | — | — | — | — | 497 | 547 | 995 |
| 48" | — | — | — | — | 500 | 550 | 1000 |
To keep a copy by the tank, use your browser's print or "save as PDF" option (File → Print) to print this oil tank chart.
Why your tank is never filled to the top
Oil companies leave room for thermal expansion and do not fill a tank to its rated capacity. A 275-gallon tank is typically filled to around 250 gallons (roughly 6 inches below the top), a 330 to around 300, a 500 to about 450, a 550 to about 500, and a 1000 to about 900. So a "full" delivery is normal even though the gauge does not read at the very top.
Oil below the tank's take-up screen near the bottom is generally not usable by the burner, so the last inch or two of indicated oil should not be counted on when planning your next delivery.
Frequently asked questions
How many gallons are in a 275-gallon oil tank?
A 275-gallon tank is rarely filled to a true 275 gallons. Oil companies leave room for thermal expansion, so a "full" 275 tank usually holds about 250 gallons. The amount at any given oil depth depends on whether the tank is mounted vertically or horizontally, so measure the depth with a stick and read across the chart above for your tank size and orientation.
How do I read a heating oil tank chart?
Measure the oil depth with a clean dipstick: lower it straight down until it touches the bottom, withdraw it, and read how many inches are wet with oil. Find that depth in inches in the left column of the chart, then read across to your tank size and orientation. A built-in float gauge gives only a rough indication, so a stick reading is more dependable.
What is the difference between a vertical and horizontal 275-gallon oil tank chart?
It is the same tank body (about 27 × 44 × 60 in) in two orientations. A vertical (275V) tank fills on a nearly constant footprint, so gallons rise almost linearly with depth. A horizontal (275H) tank has an oval cross-section, so the same inch of depth adds very different gallons near the bottom than in the middle. That is why the 275V and 275H columns read differently at the same depth.
How many gallons per inch are in a 275-gallon horizontal oil tank?
It is not a single fixed number, because the cross-section is oval. On a 275-gallon horizontal (275H) tank it is about 6 gallons near the 1-inch bottom reading, about 96–97 gallons at 10 inches, and roughly 11–12 gallons per inch around the middle of the tank. Use the chart rather than one per-inch figure.
Why does my oil tank chart not go all the way to the tank's nominal capacity?
Tanks are not filled to their rated size. Room is left for thermal expansion, so a 275 is typically filled to about 250 gallons, a 330 to about 300, a 500 to about 450, a 550 to about 500, and a 1000 to about 900. Oil below the take-up screen near the bottom is also generally unusable by the burner, so the last inch or two should not be counted on.
Do oil tank charts vary by manufacturer?
Yes. The values here are calculated geometric estimates, not a universal manufacturer dip chart. Real dimensions and gauge curves vary by manufacturer, model, and whether the tank is vertical or horizontal. Granby-style steel tanks are commonly used for residential heating oil, but other makers' tanks have different dimensions and will read differently.
Can I use this chart for ordering heating oil?
Yes for planning and estimating how much oil you have and roughly how much you can take. For billing and delivery, rely on your oil supplier's own measurement, since these figures are approximate estimates and not custody-transfer values.
Assumptions and limitations
This chart is a planning estimate, not an official manufacturer dip chart. It uses ideal tank geometry for common residential heating-oil tank sizes.
- Calculated estimates: Values are calculated from nominal tank dimensions, not measured from a specific manufacturer tank.
- Shape assumptions: 275H and 330H tanks are modeled as horizontal obround tanks; 500, 550 and 1000-gallon tanks are modeled as horizontal cylinders.
- Vertical tanks: 275V and 330V tanks use a vertical linear model. It is closest through the middle of the tank and less accurate near the rounded top and bottom.
- Real tanks vary: Manufacturer, model, exact dimensions, tank tilt, dents, fittings, sludge, water, and unusable bottom volume can all change the reading.
- Typical large-tank dimensions: The 48-inch diameter and 65, 72 and 130-inch lengths for 500, 550 and 1000-gallon tanks are representative values only. Other supplier charts may use different dimensions.
- Planning only: Use this chart for estimating and ordering, not for billing or custody-transfer measurement.
Disclaimer: This chart provides approximate calculated estimates only. Confirm your tank's exact size and configuration before ordering, and rely on your oil supplier's measurement for delivery and billing.
References and cross-checks
Standard residential heating-oil tank dimension references and manufacturer-style tank charts were used to cross-check common 275, 330, 500, 550 and 1000-gallon tank sizes. Commercial oil-provider charts were used only as non-linked cross-checks. Actual usable gallons can differ by manufacturer, tank tilt, fittings, sludge or water at the bottom, and delivery fill-room practice.
Volume conversions follow standard U.S. customary definitions (1 US gallon = 231 cubic inches), as documented on our methodology page.