Granby oil tank chart
Granby builds steel tanks in the standard oval sizes, so there is no separate Granby conversion math: the computed charts on this site apply directly. Match your size and orientation below and read your stick against that chart. When in doubt, the data plate on the end of the tank is the authority.
Match your Granby to its chart
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Granby 275 vertical
Oval end taller than wide (27″ by 44″), 60″ long. About 274 gallons full.
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Granby 275 horizontal
Lies flat, 27″ deep, 60″ long. The same 274 gallons on a shallower stick scale.
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Granby 330 vertical
Same end profile as the 275, stretched to 72″. About 329 gallons full.
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Granby 330 horizontal
Flat and 72″ long. About 329 gallons under a 27 inch stick scale.
Calibrated to Granby's own chart
Steel ovals have dished heads that hold about 2 percent more than flat-end math, so our tables carry that allowance, calibrated against Granby's official capacity chart for vertical tanks. The two now agree within about a gallon at every level: at 10 inches we read 51 against Granby's 51.2; at 22 inches, 137 against 136.9; full, 274 against 273.8. The same values appear in the chart books oil dealers carry.
Granby's chart also covers slim and less common verticals (120, 138, 220, 230, and 240 gallon models). For those, use the chart that shipped with the tank or run your measurements through the tank volume calculator.
The data plate settles it
Every Granby carries a plate on the tank end listing the model and capacity. Trust the plate over a previous owner's memory, a real estate listing, or a guess from across the basement. If the plate is unreadable, measure instead: 60 inches end to end is a 275, 72 inches is a 330, and the way the oval faces you tells you vertical or horizontal.
Common questions
Do these charts work for a Granby tank?
Yes. Granby builds to the standard oval dimensions, and the charts here are computed from that same geometry. Cross-check the capacity on your data plate once; if it matches the standard size, the chart applies as is.
Which size Granby do I have?
Check the data plate on the tank end first. If it is gone or painted over, measure the length: 60 inches is a 275, 72 inches is a 330. Both share the same 27 by 44 inch oval, so length is the tell. More clues in what size is my oil tank.
Is mine vertical or horizontal?
Stand at the oval end. Taller than wide means vertical, and the stick travels up to 44 inches. Wider than tall means horizontal, and the stick tops out at 27. The orientation changes the whole chart, so settle this before converting anything.
My plate shows a capacity these charts do not list. Now what?
Do not stretch the nearest chart to fit. Measure the tank and run it through the tank volume calculator, which builds a conversion from your actual dimensions.