Tank Fill Calculator (Cylinder)

For a vertical cylinder the liquid volume scales linearly with fill height: V = πr²h. Worked example: a tank with r = 2 ft and total height H = 5 ft holds 62.83 ft³ full; filled to h = 3 ft it holds π × 4 × 3 = 37.70 ft³ ≈ 282 US gal — exactly 60% of capacity. Horizontal tanks need the segment formula at the liquid depth.

1. 1

   Enter tank radius

   r = diameter/2, in ft or m.

2. 2

   Enter fill height

   Liquid level h, not the tank height H.

3. 3

   Read capacity

   Current volume, full volume and fill percentage.

• 1

  Vertical cylinders fill linearly: half height = half volume

• 2

  Horizontal tanks do NOT — they follow a circular-segment curve

• 3

  1 ft³ of water = 7.48 US gal = 62.4 lb

• Using total height H instead of liquid level h

• Treating a horizontal tank as linear

• Entering diameter where radius belongs

• Confusing US and imperial gallons