🛢️Tank Calculator
The Tank Calculator Toolset

Tank Calculators, One Engine

6 tools covering the tank jobs you actually do: capacity and fill for sizing and ordering, dip charts for the gauge stick, head geometry for real vessels, weight for stands and trucks, and tilt correction for the sloped installs everyone builds. Every calculator reads the same tank model — the same shapes, the same head formulas, the same densities — so the numbers can never quietly disagree with each other.

Open the Volume Calculator Browse by Category
Free, no sign-up Live on every keystroke Imperial & metric
Industrial storage tanks and vessels at a process plantOne toolset for the whole life of a tankPhoto: Unsplash
Live on every keystroke
Imperial & metric
10 tank shapes
Dip chart generator
No sign-up, no caps
Browse by Job

The Calculators, Categorized

Three groups, ordered the way a tank job unfolds — capacity first, then the geometry corrections that match real vessels, then what the contents weigh. Each card opens the live tool; each category intro explains when its tools are the right ones to reach for.

01

Capacity & Fill

This is where every tank question starts — how much fits. The water tank and fish tank calculators cover the most common specialized geometries, each with worked examples and real-world fill rules. Every calculator listed here returns total capacity and filled volume in US gallons, liters, and cubic feet in a single keystroke.

Reach for these when…

  • You need the total capacity of a round or rectangular tank
  • An aquarium's usable gallons after glass-wall correction
  • A dipstick reading has to become gallons or liters
  • A delivery order needs a reliable usable-volume figure
💧

Water Tank Capacity Calculator

Calculate water tank capacity in liters and gallons for round, rectangular and square tanks — surface area, weight when full, and standard sizes from 200 to 5000L.

Open the tool
🐠

Fish Tank Volume Calculator

Calculate fish tank volume in gallons and liters for rectangular, cylindrical, oval and hexagon aquariums — with glass wall thickness correction and standard sizes chart.

Open the tool
02

Geometry & Corrections

Real tanks are not simplified cylinders with flat plates on the ends. The horizontal cylinder calculator accounts for dished-end head geometry that hand formulas ignore — hemispherical, 2:1 elliptical and torispherical heads each add a different volume to the shell, and the calculator reports that contribution separately so you can see what the ends are worth.

Reach for these when…

  • Your vessel has curved, dished or elliptical heads
  • You need the shell volume separate from the head volume
  • A horizontal cylinder needs a dip chart
  • You are sizing a bullet tank, road tanker, or frac tank
🛢️

Horizontal Cylinder Tank Volume Calculator

Calculate horizontal cylinder tank volume with flat, hemispherical, or 2:1 elliptical heads — partial fill curve, oval and rectangle cross-sections, standard sizes 100-5000 gal.

Open the tool
03

Contents & Weight

Volume answers how much fits; weight answers what it loads. The propane tank and diesel fuel calculators specialize in density-sensitive liquids — propane at 0.51× water weight with a legal 80% fill rule, diesel at SG 0.84 running 7.0 lb/gal. The weight figure is what stands, pads, trailer floors and forklift plans actually need.

Reach for these when…

  • Propane sizing from BTU demand with 80% fill rule
  • Diesel fuel tank weight for truck road-weight limits
  • Heating oil usable capacity vs. nameplate
  • Delivery top-up math from a dip chart reading
🔥

Propane Tank Size Calculator

Size a propane tank from BTU demand, check 80% fill rule capacity, and convert propane volume to weight — with standard tank sizes from 20lb to 1000 gal.

Open the tool
⛽

Diesel & Fuel Tank Calculator

Calculate diesel and fuel tank capacity, weight at any fill level, dip chart for horizontal oval tanks, and delivery top-up math — with standard truck and generator sizes.

Open the tool
🛢️

Heating Oil Tank Size Calculator

Heating oil tank size calculator — 275-gal oval case study, usable capacity vs nameplate, dip chart for oval tanks, standard sizes 150-550 gal.

Open the tool
One Model, Proven

One Tank, Four Tools, Zero Disagreement

The test of a shared model is simple: run the same tank through every tool and the story has to stay consistent. Here is the classic 275-gallon home heating-oil tank through the four tools it meets most often — every figure traces back to the same 27 × 44 × 60 inch oval geometry.

STEP 1

Volume calculator

268 US gallons total

A classic 275-gal home heating-oil tank — 27" × 44" × 60" with an oval cross-section — works out to 268 gal of geometric capacity. The nameplate rounds up.

STEP 2

Dip chart generator

≈21% at quarter depth

An 11-inch dipstick reading in that tank is about 57 gallons — 21% of capacity, not the 25% a straight-line guess would give. The strapping table converts every future reading to gallons on sight.

STEP 3

Liquid weight converter

≈1,900 lb of heating oil

Heating oil runs SG 0.85 — about 7.1 lb per gallon. Two hundred gallons in the tank puts over 1,400 lb on the stand and the floor joists.

STEP 4

Tilt correction

Real volume at the real angle

Installers slope oil tanks toward the drain end. At 1.5° over 60 inches the ends differ by 1.6 inches of depth — the correction integrates the whole length.

A technician measuring a storage tank before running the calculatorSame tank, every tool, every timePhoto: Unsplash

Why This Matters on a Real Job

The classic failure is not one bad number — it is two good numbers that were never talking. A stand sized for water while the tank holds oil. A delivery ordered from a linear guess of the dipstick. A capacity quoted from a flat-end formula on a dished vessel. Each one is an honest mistake made across tool boundaries.

Sharing one model is the structural fix. The head geometry that sets your capacity also sets your dip chart; the density that weighs your inventory also loads your truck. When the definitions are shared, the mistakes get caught by arithmetic instead of by the crew.

Run your tank now
Quick Router

Which Tool Answers Your Question?

Find the question you are holding, follow the row, open the tool. Every calculator is one click from this table — and back to the volume engine when the next question starts.

If you need to know…
Open…
You get…
How many gallons does this tank hold?
💧Water Tank Capacity Calculator
Capacity in gal, L, m³, ft³
How much is in it right now?
⛽Diesel & Fuel Tank Calculator
Filled volume and % full with SG
What volume does my dipstick reading mean?
🛢️Heating Oil Tank Size Calculator
Oval cross-section dip chart
How much can I still add before it is full?
🛢️Horizontal Cylinder Tank Volume Calculator
Partial fill curve + ullage
Do the dished ends change the capacity?
🛢️Horizontal Cylinder Tank Volume Calculator
Flat vs hemisphere vs 2:1 elliptical
What size propane tank do I need?
🔥Propane Tank Size Calculator
BTU demand → tank size with 80% fill
What will the contents weigh when full?
⛽Diesel & Fuel Tank Calculator
lb, kg and tons at any SG
I need a tank that holds X gallons — what size should it be?
💧Water Tank Capacity Calculator
Round / rectangular sizing by volume
How many liters is my fish tank?
🐠Fish Tank Volume Calculator
Gallon ↔ liter after glass correction
The Core Tool

Inside the Tank Volume Calculator

The volume calculator is where the whole toolset begins, and its inputs are the vocabulary every other tool assumes you know. Six settings do all the work — each one mapped to a decision you make on the job, none of them hidden behind an account or a paywall.

10 tank shapes

Horizontal and vertical cylinders, rectangle, ovals, capsules, ellipse, 2:1 elliptical and dish ends — the full field repertoire in one dropdown.

Dish-end head geometry

Flat, hemispherical, 2:1 elliptical and torispherical heads, each reported separately from the shell, with custom dish depth support.

Liquid weights built in

Water, diesel, gasoline, milk, crude oil and more — or a custom density in SG, kg/m³ or lb/gal — converted to pounds, kilograms and tons.

Imperial and metric together

Each dimension carries its own unit selector — in, ft, yd, mm, cm, m — and every result shows its twin so cross-border spec sheets never need a second conversion.

Tilt correction

Sloped installations are the norm, not the exception. Enter the angle and where you dipped, and the engine integrates the depth along the whole shell.

Live on every keystroke

No calculate button, no sign-up, no result caps. Change a dimension and watch the diagram, volume and weight move before your finger leaves the key.

From Dimensions to a Defensible Number

Under the hood the engine runs the closed-form volume of the shape you picked, the circular-segment integral for anything partially filled, the head formulas when the ends are not flat, and the density conversion when weight matters. Nothing is tabulated or approximated behind the curtain — every figure traces to a formula the site publishes.

The outputs are organized the way the work is read: capacity first, because it drives sizing and ordering; then the filled volume and ullage that drive deliveries; then the weight that drives stands, pads and trucks. The dip chart turns the same geometry into a field document.

Walk the full how-to
Gauge measurements being taken on an industrial tankTwo dimensions in, every number outPhoto: Unsplash
Trust, Then Verify

Four Hand Checks for Any Result

A calculator that hides its math is asking for blind trust; this one does not. Every figure the toolset produces can be reproduced with a tape measure, a phone calculator, and the four checks below — the same mental math operators have used for decades, refined to the decimal by the engine. Run them once on a tank you already know, and the tool has earned its place on the job.

1

Check the capacity against the πr²L rule

gal ≈ 0.0034 × D² × L

Full-cylinder capacity in US gallons from diameter and length in inches — a 27" × 60" tank works out to 148.7 gal. Run the calculator on the same tank: the totals should match to the decimal, because both come from the same geometry (π × 13.5² × 60 = 34,353 in³ ÷ 231).

2

Check the fill against the quarter-depth curve

25% depth ≈ 19.6% of volume

A horizontal cylinder filled to a quarter of its depth holds about a fifth of its capacity — the circle is narrow at the bottom. Any dip-chart row that disagrees wildly with this curve on a round tank has an input problem: the wrong diameter, the wrong depth basis, or the wrong tank.

3

Check the heads against πr³/3

2:1 elliptical head = πr³/3 each

One 2:1 elliptical head holds πr³/3 — on a 27" tank that is about 2,576 in³ per head, or 22.3 gallons for the pair. The head-vs-shell breakdown should show exactly that figure for the 2:1 option, with the hemispherical rows above it and the F&D rows below it in the same proportion.

4

Check the weight against 8.34 lb/gal

lb = gal × 8.34 × SG

Water weighs 8.34 lb per gallon; multiply by the liquid's specific gravity for anything else — diesel at SG 0.84 runs about 7.0 lb/gal. A 148.7-gallon tank of diesel should read roughly 1,040 lb full, and the weight converter will show it to the pound.

Tank reference charts and a laptop with the tank calculator open on a workbenchEvery tool has a guide behind itPhoto: Unsplash
Tools + Guides

Not Sure Which Number to Trust? Read the Guide.

Every calculator on this page has a matching set of guides that explain the ideas behind its inputs — what a dip chart actually tabulates, why curved heads change capacity, where the circular-segment integral comes from, and how to check a supplier's capacity figure against your own measurements.

The guides and the tools are written as a pair: the reading explains why a number moves, the tool shows how far it moves. If a result ever surprises you, the guide library is the fastest way to find out whether the surprise is the math or the measurement.

Browse the guide library

Questions About the Toolset

Are all of the calculators free to use?▼

Yes — every tool on this page is free, requires no account, and has no usage caps or paywalled fields. The site is a reference toolset, not a lead-generation funnel: nothing gates a result, and no result is emailed to anyone.

Do the calculators share inputs with each other?▼

They share the geometry, not a session. Each tool is a view of the same tank model — the dip chart generator reads the same dimensions and head settings as the main volume calculator — so a figure from one tool is always consistent with the others. There is no second copy of the math to drift out of date.

Where do the numbers come from?▼

Exact solid geometry. Total capacity follows the closed-form volume of each shape; partial fills use the circular-segment and spherical-cap integrals the industry handbooks publish; head volumes use the standard per-head formulas (πr³/3 for 2:1 elliptical, 0.0809·D³ for ASME F&D style dished ends). Each section of the site shows the formula it applies so you can verify any result by hand.

Which calculator should I start with?▼

The tank volume calculator. It is the hub: the capacity and filled-volume figures it produces feed dip charts, weight planning and head corrections. Start with the shape and inside dimensions you actually have, then follow the links from this page to the tool that answers the next question about that same tank.

Can I work in metric only?▼

Yes. Every dimension field has its own unit selector — millimeters, centimeters and meters included — and results appear in liters and cubic meters beside the US units. A metric-only run never needs a manual conversion, and an imperial nameplate can be entered inch by inch on the same page.

How can I verify a result before I rely on it?▼

Use the four hand checks on this page: the πr²L capacity rule, the quarter-depth fill curve, the πr³/3 head factor, and 8.34 lb/gal times specific gravity. Each one reproduces a calculator output from published geometry, so any number can be confirmed in about a minute — without trusting anyone's code, ours included.

Can I request a calculator that is not here yet?▼

Please do. Send the calculation you keep doing by hand — what inputs you start from, what result you need out — through the contact page. Requests that describe a real, repeated field problem go to the top of the queue, and the toolset grows the same way the guide library does: from questions that were worth writing down.

Run Your First Tank Now

Pick a shape, enter the inside dimensions, and set a fill depth — the engine returns capacity, filled volume, ullage and weight in one keystroke. Then generate the dip chart the gauge stick deserves. Free, private, and instant.

Open the Tank Volume Calculator Read the Guides First