# tankvolumecalc.com

> Free tank volume tools built on exact closed-form geometry — circular segments, a piecewise obround model for 275/330 heating-oil tanks, and scaled spherical caps for dished propane heads. No interpolation and no lookup tables. Every unit factor is traced to the standard that defines it (NIST Handbook 44, the 1959 International Yard and Pound Agreement, the BIPM SI Brochure, the UK Weights and Measures Act 1985). All calculation runs client-side; nothing entered is stored or transmitted. Methodology, derivations and sources are published rather than asserted.

## Calculators
- [Horizontal Cylinder Tank calculator](https://tankvolumecalc.com/horizontal-cylinder/): Volume of a horizontal cylindrical tank — total and at any liquid depth. Free, exact, in-browser.
- [Vertical Cylinder Tank calculator](https://tankvolumecalc.com/vertical-cylinder/): Volume of an upright cylindrical tank in gallons and liters. Free, exact, in-browser.
- [Rectangular Tank Volume calculator](https://tankvolumecalc.com/rectangular/): Volume of rectangular tanks, totes, sumps and aquariums. Free, exact, in-browser.
- [Heating Oil Tank Volume calculator](https://tankvolumecalc.com/heating-oil-tank/): Exact obround math for 275 and 330 gallon heating oil tanks. Free, exact, in-browser.
- [Propane Tank Volume calculator](https://tankvolumecalc.com/propane-tank/): Propane vessel volume with dished heads, gauge % and the 80% fill rule. Free, exact, in-browser.
- [Oval Tank Volume calculator](https://tankvolumecalc.com/oval-tank/): Elliptical horizontal tank volume at any fill depth. Free, exact, in-browser.
- [Vertical Tank with Dished Bottom calculator](https://tankvolumecalc.com/dished-bottom/): Vertical cylinder with a 2:1 ellipsoidal bottom head, at any level. Free, exact, in-browser.
- [Cone Bottom Tank calculator](https://tankvolumecalc.com/cone-bottom/): Volume of vertical tanks with conical bottoms at any level. Free, exact, in-browser.
- [Sphere Tank Volume calculator](https://tankvolumecalc.com/sphere/): Spherical vessel volume and partial fill (spherical cap). Free, exact, in-browser.
- [Frustum / Tapered Tank Volume calculator](https://tankvolumecalc.com/frustum/): Volume of tapered vessels, buckets and hoppers. Free, exact, in-browser.
- [Pipe Volume calculator](https://tankvolumecalc.com/pipe-volume/): Water volume and weight inside a pipe, per length. Free, exact, in-browser.
- [Tank fill time calculator](https://tankvolumecalc.com/fill-time/): How long to fill or drain a tank at a given GPM. Free in-browser calculator.

## Field tools
- [Thermal expansion & ullage calculator](https://tankvolumecalc.com/thermal-expansion/): How much fuel expands with temperature: ΔV = V×β×ΔT with sourced coefficients (diesel 0.00046/°F per Chevron). Ullage check, max safe temperature, fill recommendations. Codes govern.
- [Custom dip chart generator](https://tankvolumecalc.com/dip-chart-generator/): Generate a laminate-ready dip chart (strapping chart) for any tank: enter dimensions, choose 1-inch to 5-cm steps, download a printable PDF with exact partial-fill geometry.

## Tank charts (24 tanks, inch-by-inch, printable PDF)
- [10 Gallon Aquarium](https://tankvolumecalc.com/charts/10-gallon-aquarium/): 10.4 gal geometric, 12 rows to 12 in
- [1000 Gallon Propane Tank](https://tankvolumecalc.com/charts/1000-gallon-propane-tank/): 1000 gal geometric, 41 rows to 41 in
- [1000 Gallon Underground Oil Tank](https://tankvolumecalc.com/charts/1000-gallon-underground-oil-tank/): 1018.4 gal geometric, 48 rows to 48 in
- [120 Gallon Propane Tank](https://tankvolumecalc.com/charts/120-gallon-propane-tank/): 120 gal geometric, 24 rows to 24 in
- [125 Gallon Aquarium](https://tankvolumecalc.com/charts/125-gallon-aquarium/): 117.8 gal geometric, 21 rows to 21 in
- [1500 Gallon Underground Oil Tank](https://tankvolumecalc.com/charts/1500-gallon-underground-oil-tank/): 1504 gal geometric, 64 rows to 64 in
- [20 Gallon High Aquarium](https://tankvolumecalc.com/charts/20-gallon-aquarium/): 19.9 gal geometric, 16 rows to 16 in
- [2000 Gallon Underground Oil Tank](https://tankvolumecalc.com/charts/2000-gallon-underground-oil-tank/): 2005.4 gal geometric, 64 rows to 64 in
- [250 Gallon Propane Tank](https://tankvolumecalc.com/charts/250-gallon-propane-tank/): 250 gal geometric, 30 rows to 30 in
- [275 Gallon IBC Tote](https://tankvolumecalc.com/charts/275-gallon-ibc-tote/): 275.1 gal geometric, 36 rows to 35.3 in
- [275 Gallon Oil Tank (Horizontal)](https://tankvolumecalc.com/charts/275-gallon-oil-tank-horizontal/): 267.9 gal geometric, 27 rows to 27 in
- [275 Gallon Oil Tank (Vertical)](https://tankvolumecalc.com/charts/275-gallon-oil-tank-vertical/): 267.9 gal geometric, 44 rows to 44 in
- [29 Gallon Aquarium](https://tankvolumecalc.com/charts/29-gallon-aquarium/): 28.1 gal geometric, 18 rows to 18 in
- [320 Gallon Propane Tank](https://tankvolumecalc.com/charts/320-gallon-propane-tank/): 320 gal geometric, 30 rows to 30 in
- [330 Gallon IBC Tote](https://tankvolumecalc.com/charts/330-gallon-ibc-tote/): 330 gal geometric, 40 rows to 39.7 in
- [330 Gallon Oil Tank (Horizontal)](https://tankvolumecalc.com/charts/330-gallon-oil-tank-horizontal/): 321.5 gal geometric, 27 rows to 27 in
- [330 Gallon Oil Tank (Vertical)](https://tankvolumecalc.com/charts/330-gallon-oil-tank-vertical/): 321.5 gal geometric, 44 rows to 44 in
- [40 Gallon Breeder Aquarium](https://tankvolumecalc.com/charts/40-gallon-aquarium/): 44.9 gal geometric, 16 rows to 16 in
- [500 Gallon Propane Tank](https://tankvolumecalc.com/charts/500-gallon-propane-tank/): 500 gal geometric, 38 rows to 37.5 in
- [500 Gallon Underground Oil Tank](https://tankvolumecalc.com/charts/500-gallon-underground-oil-tank/): 501.3 gal geometric, 48 rows to 48 in
- [55 Gallon Aquarium](https://tankvolumecalc.com/charts/55-gallon-aquarium/): 56.7 gal geometric, 21 rows to 21 in
- [55 Gallon Drum](https://tankvolumecalc.com/charts/55-gallon-drum/): 57.7 gal geometric, 34 rows to 33.5 in
- [550 Gallon Underground Oil Tank](https://tankvolumecalc.com/charts/550-gallon-underground-oil-tank/): 551.8 gal geometric, 42 rows to 42 in
- [75 Gallon Aquarium](https://tankvolumecalc.com/charts/75-gallon-aquarium/): 78.5 gal geometric, 21 rows to 21 in

## Reference libraries
- [Tank sizes & dimensions.](https://tankvolumecalc.com/sizes/): dimensions, capacities, weights and siting rules for 34 standard tanks
- [Volume conversions.](https://tankvolumecalc.com/convert/): 15 volume converters, each with the exact factor, its derivation from first definitions, worked examples and a rounding-error table
- [What liquids weigh.](https://tankvolumecalc.com/weight/): lb/gal and kg/L for 21 liquids with cited densities and their temperature basis
- [Tank volume formulas.](https://tankvolumecalc.com/formulas/): 12 shapes: total and partial-fill formula, derivation, worked example, 5%-step fill table, downloadable PDF
- [Water tank capacity, in litres.](https://tankvolumecalc.com/litres/): metric-first calculators and Indian household sizing
- [Tank fill time calculator](https://tankvolumecalc.com/fill-time/): time to fill or drain, for 10 standard volumes

## Guides (15)
- [Choosing an Aquarium Size (and What the Gallons Really Mean)](https://tankvolumecalc.com/guides/choosing-aquarium-size/): Aquarium sizes are brim-full nominal ratings, and the number on the box is the least useful volume in the hobby. A "55 gallon" (48×13×21 in) ho
- [Heating Oil Tank Sizes, Explained](https://tankvolumecalc.com/guides/heating-oil-tank-sizes/): Residential heating oil tanks come in a small family of standard sizes, and once you know the family the measurements identify your tank instantly.
- [How Long Will My Heating Oil Last?](https://tankvolumecalc.com/guides/how-long-will-heating-oil-last/): Heating oil carries about 138,500 BTU per gallon, and your burner's nozzle tells you the burn rate: a typical residential nozzle is 0.75–1.0 gallons 
- [How Long Will a Propane Tank Last?](https://tankvolumecalc.com/guides/how-long-will-propane-last/): Propane delivers about 91,500 BTU per gallon, so runtime is appliance BTU rating ÷ 91,500 = gallons per hour at full fire. A 100,000 BTU/hr furnace 
- [How Much Oil Is Left in My Tank? (The Stick Method)](https://tankvolumecalc.com/guides/how-much-oil-is-left/): Float gauges fail slowly and lie politely. The stick method takes two minutes and doesn't.
- [How Much Propane Is Left in My Tank?](https://tankvolumecalc.com/guides/how-much-propane-is-left/): One multiplication answers it: gauge percent × water capacity = gallons of propane. A 500-gallon tank reading 38% holds 190 gallons; a 250 at 60% hol
- [How to Measure a Tank When You Don't Know What It Is](https://tankvolumecalc.com/guides/how-to-measure-an-unknown-tank/): Every chart and calculator needs the same three facts: the shape, the inside dimensions, and the orientation. Here's how to get them off an unlabeled tank.
- [How to Read a Tank Chart (Without Squinting)](https://tankvolumecalc.com/guides/how-to-read-a-tank-chart/): A tank chart converts a depth measurement into gallons. Three things trip people up, and all three are fixable in thirty seconds.
- [IBC Totes: Capacity, Markings and Measuring](https://tankvolumecalc.com/guides/ibc-tote-basics/): The two standard Intermediate Bulk Containers hold 275 and 330 gallons (about 1,000 and 1,250 litres) in a blow-molded bottle inside a galvanized cage on a
- [How to Measure an Underground Tank You Can't See](https://tankvolumecalc.com/guides/measure-underground-tank/): Underground tanks hide their geometry, but you can recover it with a stick, the fill pipe, and one delivery receipt.
- [Oil Tank Gauge Stuck or Not Working? Here's How to Check It](https://tankvolumecalc.com/guides/oil-tank-gauge-not-working/): Float gauges fail in boring, predictable ways: the float hinge gums up, the disc sticks at the top of the sight tube, or the indicator drifts. The symptom 
- [Reading a Propane Tank Gauge (And the 80% Rule)](https://tankvolumecalc.com/guides/propane-tank-gauge/): Propane gauges confuse people because the tank plays by different rules than any other container you own.
- [Tank Chart vs Gauge: Which Number Do You Trust?](https://tankvolumecalc.com/guides/tank-chart-vs-gauge/): They answer differently because they measure differently. A float gauge is a mechanical estimate with real-world slop — ±5% is typical when he
- [Water in Your Oil Tank: How to Find It and What to Do](https://tankvolumecalc.com/guides/water-in-your-oil-tank/): Water gets into oil tanks three ways: condensation on the cold steel walls of a part-empty tank, a loose or missing fill cap, and (for buried tanks) ground
- [What Is Ullage (and Why Tanks Are Never Quite Full)](https://tankvolumecalc.com/guides/what-is-ullage/): Ullage is the empty space between the liquid surface and the top of the tank — and it exists on purpose.

## By application
- [Aquariums: real water volume, not the box rating](https://tankvolumecalc.com/for/aquariums/): Rated gallons are brim-full; your fish live in the working volume. Charts for every standard size, calculators for customs, and the substrate-aware me
- [Farm & Ag: fuel, fertilizer, water — and the axle math](https://tankvolumecalc.com/for/farm-and-ag/): Skid tanks, totes and transfer tanks live or die on weight: a tote of UAN is a third heavier than water. Charts for the tanks, weights for the loads, 
- [Heating Oil: everything for the oil-heated home](https://tankvolumecalc.com/for/heating-oil/): Stick the tank, read the chart, know when to order — the full toolkit for 275/330 obround tanks and underground cylinders, built on geometry that matc
- [Propane: gauges, fill rules and vessel math](https://tankvolumecalc.com/for/propane/): Gauge % × water capacity = gallons, full means 80%, and the dished-head geometry behind every chart is measured against exact vessel math.
- [Water Storage: household sizing to rainwater math](https://tankvolumecalc.com/for/water-storage/): Litres-first tools for overhead tanks and sumps, IS 1172 household sizing, and the harvesting arithmetic — plus everything in gallons for US storage.

## Answers and definitions
- [FAQ](https://tankvolumecalc.com/faq/): 81 questions, searchable, across geometry, dip charts, units, standard sizes, fuel consumption and regulations
- [Glossary](https://tankvolumecalc.com/glossary/): 91 terms, alphabetical and searchable
- [Methodology](https://tankvolumecalc.com/methodology/): every formula derived, with the automated tolerance tests that gate each build

## Full detail
- [llms-full.txt](https://tankvolumecalc.com/llms-full.txt): complete page inventory, exact unit definitions and the standards behind them

Last updated: 2026-09-02