Tank Volume Calculator (Partial Fill)

How many liters are in your horizontal or vertical cylindrical tank at a given dip level — plus total capacity and fill percentage.

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Dipstick to Liters

For a horizontal cylinder, liquid at height h forms a circular segment: A = r²·acos((r−h)/r) − (r−h)·√(2rh−h²), and volume = A × tank length — the classic "I measured 40 cm with a stick, how many liters is that?" problem that a simple πr²h can't answer. Vertical cylinders are linear: V = π·r²·h. The tool gives current liters, total capacity, fill percentage and remaining space.

Assumes flat ends; dished or conical heads add a few percent — check the manufacturer's chart for custody transfer.

Frequently Asked Questions

Why isn't 50% height equal to 50% volume in a horizontal tank?

It is exactly 50% at half height — but nowhere else is linear: at 25% of the diameter the tank holds only about 20% of its volume, because the segment area grows non-linearly. That is why this calculator exists.

How accurate is a dipstick reading?

On a level tank with flat ends, within 1-2%. Sloped installation, dished heads and foam throw it off — for fuel sales use calibrated charts.

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