Tank Dimensions
Tank Capacity Results
Enter dimensions to see calculation steps
⚡ Quick Answers
Need this calculator? Yes. Wrong size costs money or leaves you dry.
How to use? Enter length, width, height → Click calculate.
Dead space? Add 10-20%. Sediment takes room.
✅ 5 Tips That Help
- Measure inside. Tank walls steal space.
- Add 20% buffer. Dry spells happen. Needs grow.
- Plan for sludge. Dirt settles at bottom. Subtract 2-3 inches from height.
- Use one unit. Feet or inches. Not both. Mixing = wrong answer.
- Check local codes. Some cities require minimum gallons for fire safety.
📌 FAQ
Formula for a rectangular tank?
Length × Width × Height = cubic feet. Multiply by 7.48 to get US gallons.
Inches to feet?
Inches ÷ 12 = feet. Example: 6 inches = 0.5 feet. Calculator does this for you.
US vs Imperial gallons?
US gallon = 3.785 liters. Imperial = 4.546 liters (20% bigger). Calculator shows both.
Water weight?
8.34 pounds per US gallon. A 1,000 gallon tank holds 8,340 lbs. Check your floor.
Fuel or oil?
Yes. Volume math is same. Weight differs. Fuel is lighter.
📏 Common Rectangular Tank Sizes
💬 Real Talk
Under-sizing is #1 mistake. People run dry because their tank is 20% too small. Add a buffer.
Don't trust outside measurements. A 1/2 inch wall on a 6 ft tank loses ~15 gallons.
Sediment is real. After 2-3 years, expect 2-4 inches of sludge. That's water you can't use.
— Nasir, 10+ years in excavation & water storage
Disclaimer: This calculator gives estimates. Real tanks vary. Double-check with your supplier for critical projects.
© MultiTooSite — Real numbers, no fluff.
10+ years in excavation, concrete, and site work