Cubic Feet to Gallons CalculatorWater Tank & Aquarium Volume Converter
Convert cubic feet (ft³) to gallons instantly with our free calculator. Essential tool for calculating water tank capacity, aquarium volume, swimming pool size, and liquid storage containers. Supports both US gallons (liquid) and UK (Imperial) gallons for international users. Simply enter your cubic feet measurement to get accurate gallon conversions with clear formula explanation. Perfect for plumbers, aquarium enthusiasts, pool owners, homeowners, and DIY projects requiring liquid capacity calculations.
Calculate Cubic Feet to Gallons
Convert ft³ to gallons for water tanks, aquariums, and pools
Enter the volume in cubic feet
Result in US gallons
Also equals:
Liters
283.17 L
Cubic Inches
17,280 in³
UK Gallons
62.29 UK gal
Calculation:
10 ft³ × 7.48052 = 74.8 US gal
Formula: US Gallons = Cubic Feet × 7.48052
Cubic Feet to Gallons Conversion Table
Quick reference for common ft³ to gallon conversions (US & UK).
| Cubic Feet (ft³) | US Gallons | UK Gallons | Common Use |
|---|---|---|---|
| 0.5 ft³ | 3.74 gal | 3.11 gal | Small aquarium |
| 1 ft³ | 7.48 gal | 6.23 gal | Standard conversion |
| 2 ft³ | 14.96 gal | 12.46 gal | 10 gallon tank |
| 5 ft³ | 37.40 gal | 31.14 gal | 30–40 gallon tank |
| 6.68 ft³ | 50.00 gal | 41.61 gal | 50 gal water heater |
| 10 ft³ | 74.81 gal | 62.29 gal | 75 gallon aquarium |
| 13.37 ft³ | 100.01 gal | 83.28 gal | 100 gal aquarium |
| 20 ft³ | 149.61 gal | 124.58 gal | Large aquarium |
| 50 ft³ | 374.03 gal | 311.44 gal | Small pool/pond |
| 66.84 ft³ | 500.00 gal | 416.34 gal | 500 gal pool |
| 100 ft³ | 748.05 gal | 622.88 gal | Medium pool |
| 200 ft³ | 1,496.10 gal | 1,245.77 gal | Large pool |
Common Tank Sizes & Capacities
Standard water tanks, aquariums, and pools in cubic feet and gallons.
Water Heaters & Storage Tanks
30 gal
Water Heater
40 gal
Water Heater
50 gal
Water Heater
Most Popular80 gal
Water Heater
Aquarium Sizes
10 gal
Aquarium
20 gal
Aquarium
55 gal
Aquarium
Popular75 gal
Aquarium
125 gal
Aquarium
Swimming Pool Sizes
5,000 gal
Small Pool
15,000 gal
Medium Pool
Average Size30,000 gal
Large Pool
Conversion Formula Explained
US Gallons (Liquid)
US Gallons = ft³ × 7.48052
Used in the United States
UK Gallons (Imperial)
UK Gallons = ft³ × 6.22884
Used in the UK & Commonwealth
Understanding the difference
US gallons and UK (Imperial) gallons are different measurements. UK gallons are about 20% larger than US gallons, so always specify which gallon type you're using.
- US Gallon: 231 cubic inches = 3.785 liters
- UK Gallon: 277.42 cubic inches = 4.546 liters
- 1 ft³ = 7.48052 US gallons
- 1 ft³ = 6.22884 UK gallons
Step-by-step example (US gallons)
Calculate the capacity of a water tank that is 4ft × 2ft × 3ft:
- Calculate volume: 4 × 2 × 3 = 24 ft³
- Apply formula: 24 × 7.48052 = 179.53
- Result: ~180 US gallons
Practical aquarium example
You want a 75-gallon aquarium. Convert gallons to cubic feet:
75 ÷ 7.48052 = 10.02 ft³
A common 75-gallon size is roughly 48" × 18" × 21" (4ft × 1.5ft × 1.75ft).
Measure your container
Measure the length, width, and height of your tank or container in feet. Multiply these to get cubic feet.
Enter cubic feet value
Type the cubic feet value into the calculator.
View gallon capacity
The calculator instantly displays the capacity in US gallons (and UK gallons if needed).
Use for planning
Use the gallon value to determine water heater size, chemical dosing, or filtration requirements.
When to Use This Conversion
Common applications for cubic feet to gallons conversion.
Water Tanks & Heaters
Convert tank volume to gallons to size water heaters, plan storage, and estimate refill needs.
Example: A 10 ft³ tank holds about 75 gallons.
Aquariums
Estimate aquarium capacity for stocking, filtration, and water-change planning.
Example: A 75-gallon aquarium is about 10.02 ft³.
Swimming Pools
Convert pool volume to gallons for chemical dosing, pump sizing, and refill estimates.
Example: 15,000 gallons is roughly 2,005 ft³.
Liquid Storage
Convert container volume to gallons for drums, totes, and storage planning.
Example: Know gallons before ordering supplies or additives.
DIY Projects
Use gallons to estimate material needs for ponds, fountains, and rainwater collection.
Example: Convert ft³ from measurements to gallons instantly.
Maintenance & Dosing
Many dosing guides are per gallon. Convert volume so you can follow instructions accurately.
Example: Helps avoid overdosing chemicals or conditioners.
Frequently Asked Questions
Answers to common questions about ft³ to gallons conversions.