What is a Feet-Based Aquarium Calculator?
A feet-based aquarium calculator converts fish tank dimensions measured in feet directly into liquid gallons, litres, and total filled weight, facilitating custom aquarium construction.
Learn more about aquarium dimensions, sizing, and setup in the Aqueon Setting Up a Freshwater Aquarium guide.
Cubic Feet Aquarium Formulas
Cubic Feet Volume:
Volume (ft³) = Length (ft) × Width (ft) × Height (ft)
US Gallons Conversion:
Capacity (US Gal) = Volume (ft³) × 7.48052
Litres Conversion:
Capacity (Litres) = Volume (ft³) × 28.31685
How to Calculate Large Aquariums Measured in Feet
- Measure Tank Dimensions in Feet: Record length, width, and height in decimal feet.
- Calculate Cubic Feet: Multiply length × width × height.
- Convert to Gallons: Multiply cubic feet by 7.48052 to find total US Gallons.
- Account for Aquascaping: Subtract 10% for substrate and driftwood.
Large Tank Sizing Example
For a custom living room aquarium measuring 6 ft long, 2 ft wide, and 2.5 ft high:
Cubic Feet Volume = 6 × 2 × 2.5 = 30 ft³Total US Gallons = 30 × 7.48052 = 224.42 US GallonsTotal Litres = 30 × 28.31685 = 849.51 Litres
Custom Large Aquarium Size & Feet Conversion Chart
| Tank Dimensions (Feet: L × W × H) | Cubic Feet (ft³) | US Gallons | Litres |
|---|---|---|---|
| 4 ft × 1.5 ft × 2 ft | 12 ft³ | 89.76 gal | 339.80 L |
| 6 ft × 2 ft × 2 ft | 24 ft³ | 179.53 gal | 679.60 L |
| 6 ft × 2 ft × 2.5 ft | 30 ft³ | 224.42 gal | 849.51 L |
| 8 ft × 2 ft × 2.5 ft | 40 ft³ | 299.22 gal | 1,132.67 L |
| 10 ft × 3 ft × 3 ft | 90 ft³ | 673.25 gal | 2,548.52 L |
Floor Load Capacity & Substrate Weight
Large aquariums over 200 gallons weigh over 2,000 lbs (1 Metric Ton). Always consult a structural engineer before placing large tanks on second-floor timber joists.
Converting Foot Measurements to Fish Tank Capacity
When measuring custom aquariums in feet, 1 cubic foot equals approximately 7.48 US gallons or 28.32 litres. Remember to subtract wall thickness (especially for thick acrylic or glass tanks) to calculate exact internal volume.