The calculation, without hidden assumptions
Tank capacity is simple only when the cross-section fills linearly. A rectangular or vertical cylindrical tank can be scaled directly by liquid depth, but a horizontal cylinder, ellipse or capsule needs segment geometry because equal depth changes do not hold equal volume. MAXScanner accepts inside dimensions in feet, inches, metres or centimetres, calculates both full and current volume, shows the remaining capacity and can turn an entered liquid density and flow rate into mass and fill/drain time. The tank shape stays explicit so an “oval” is not silently treated as a circle.
How to use this calculator
Choose the installed tank shape and dimension unit, then enter inside dimensions rather than outside shell dimensions whenever wall thickness is material.
Enter liquid depth vertically from the lowest internal point; MAXScanner uses nonlinear segment geometry for horizontal round/elliptical/capsule tanks.
Optionally enter liquid density in kg/L and a flow rate in L/min to estimate current liquid mass, time to drain the current contents and time to fill the remaining capacity.
Where people use it
- •Water, fuel and utility tank capacity checks
- •Dipstick-depth to partial-volume conversion for horizontal tanks
- •Comparing litres, US gallons, Imperial gallons, cubic metres and cubic feet
- •Estimating current liquid mass and simple fill/drain time from entered density and flow
Example: horizontal 4 ft diameter × 10 ft cylinder at 1 ft depth
A horizontal cylinder does not contain 25% of its volume at 25% of its depth. The circular-segment formula gives roughly 19.6% full at one quarter of the diameter, which is why dipstick conversion needs tank geometry.
What the result does not assume
- •Use inside dimensions. Real tanks can include wall thickness, dished heads, baffles, dead space, fittings, slopes and unusable heel volume that change usable capacity.
- •Horizontal ellipse means a true elliptical cross-section; an obround/stadium tank is a different shape and should not be approximated as an ellipse when accuracy matters.
- •Flow-time results assume a steady entered flow rate and ignore head, pump curve, valve losses and changing flow conditions.
Frequently asked questions
Why is a horizontal cylindrical tank not linear with fill depth?+
The wetted width of the circular cross-section changes with depth. Near the bottom and top, a depth change adds less area than it does near the middle.
Does the calculator use US or Imperial gallons?+
It shows both. The same geometric volume is converted independently to US gallons and Imperial gallons, as well as litres, cubic metres and cubic feet.
Can I enter a liquid density?+
Yes. Current liquid volume is multiplied by your kg/L value to show approximate mass; density zero skips the weight calculation.
What dimensions should I measure?+
Use internal dimensions when you want fluid capacity. Outside dimensions include wall thickness and can overstate the amount the tank actually holds.
Semantic next steps
Continue the calculation
These links move to a different input, formula or project stage rather than a keyword variation of this page.
Pipe Volume Calculator — Internal Capacity in Liters & Gallons
Calculate full internal pipe capacity from actual inside diameter, length and pipe count, with liters, cubic meters and US gallons.
OpenVolume & Cubic Yard Calculator — Shapes, yd³, ft³, m³, Weight & Cost
Calculate box, cylinder, sphere or area-by-depth volume and instantly convert the result to cubic feet, cubic yards and cubic metres, with optional waste, material density, weight and bulk cost.
OpenVolume Converter
Convert liters, milliliters, cubic meters, US liquid gallons and cubic feet.
OpenPressure Converter — PSI, Bar, kPa, MPa, atm, Torr & mmHg
Convert pressure instantly between Pa, hPa, kPa, MPa, GPa, bar, mbar, psi, ksi, atm, Torr, mmHg, inHg and kgf/cm², with every equivalent, the direct factor, adjustable precision and gauge-vs-absolute guidance.
OpenPercentage Calculator
Solve percentage-of, what-percent, increase or decrease, percentage change, percentage difference and reverse percentage problems with the substituted working shown.
OpenLength Converter
Convert meters, centimeters, millimeters, kilometers, inches, feet, yards and miles with exact standard factors.
OpenCircle Calculator — Radius, Diameter, Circumference & Area
Start with radius, diameter, circumference or area and solve the other circle measurements.
OpenRectangle Calculator — Area, Perimeter & Diagonal
Calculate rectangle area, perimeter, diagonal and aspect ratio, and compare an optional measured diagonal with the calculated one to check that a layout is square.
OpenMore in this calculator collection
Browse nearby calculators in the same topic cluster so related pages reinforce each other instead of sitting as isolated URLs.
Free publisher widget
Put this calculator on your website
Give readers the live calculator without rebuilding the math. Copy the responsive embed in one click, or customize width, height, border and corner radius before publishing. The branded MAXScanner attribution stays visible.
Calculator embed HTML
Paste this code into your page. Focus the code box to select it manually.
Keep the result connected to the real job
MAXScanner keeps the formula and assumptions beside the result so you can verify the number before using it in a drawing, estimate, specification, worksheet or document. Where a supplier, manufacturer, drawing or applicable standard owns a requirement, that source remains authoritative.