Gallon Calculator
Convert between US gallons, UK gallons, liters, quarts, cups, and more. Professional calculator for fuel, water, cooking, pools, and industrial applications.
Gallon Types Explained
US Gallon: 3.785 liters
Used in the United States for fuel, water, and liquids
UK/Imperial Gallon: 4.546 liters
Used in the UK and some Commonwealth countries
US Dry Gallon: 4.405 liters
Used for dry goods like grains (rarely used today)
Volume Input
Conversion Results
Enter a volume to see conversions
Common Volume Examples
| Volume | Liters | US Cups | Description |
|---|---|---|---|
| 1 US Gallon | 3.785 | 16 | Standard US gallon |
| 1 UK Gallon | 4.546 | 19.2 | Imperial gallon |
| 5 US Gallons | 18.93 | 80 | Standard water jug |
| 10 US Gallons | 37.85 | 160 | Small aquarium |
| 20 US Gallons | 75.71 | 320 | Medium aquarium |
| 55 US Gallons | 208.2 | 880 | Standard drum |
Practical Applications
Swimming Pool
Residential pool volume
Typical Capacity
10,000-20,000 gal
In Liters
37,854-75,708 L
Car Fuel Tank
Standard vehicle capacity
Typical Capacity
12-20 gal
In Liters
45-76 L
Hot Tub/Spa
6-8 person capacity
Typical Capacity
300-500 gal
In Liters
1,136-1,893 L
Water Heater
Residential tank capacity
Typical Capacity
40-80 gal
In Liters
151-303 L
Aquarium (Large)
Home aquarium sizes
Typical Capacity
55-125 gal
In Liters
208-473 L
Rain Barrel
Water collection system
Typical Capacity
50-100 gal
In Liters
189-379 L
Understanding Gallons
US vs UK Gallons
The US gallon (3.785 L) is about 20% smaller than the UK/Imperial gallon (4.546 L). This difference is crucial for international trade and fuel calculations.
Common Relationships
- 1 US gallon = 4 quarts = 8 pints = 16 cups
- 1 US gallon = 128 fluid ounces
- 1 US gallon = 231 cubic inches
- 1 US gallon = 0.134 cubic feet
Historical Context
The gallon originated from medieval measurements. The US gallon is based on the wine gallon, while the UK gallon evolved from the ale gallon.
Water Weight Facts
Temperature Effects
Water density decreases as temperature increases. Cold water (4°C) is densest at 1.000 kg/L, while hot water (30°C) is about 0.996 kg/L.
Weight Rules of Thumb
- 1 US gallon of water ≈ 8.34 pounds
- 1 UK gallon of water ≈ 10.02 pounds
- 1 liter of water ≈ 1 kilogram (at 4°C)
- 1 cubic foot of water ≈ 62.4 pounds
Practical Applications
Water weight calculations are essential for structural engineering, shipping, pool maintenance, and fuel efficiency calculations.
Conversion Tips & Shortcuts
Quick Conversions
- • US gal to L: Multiply by 3.785
- • UK gal to L: Multiply by 4.546
- • Gal to cups: Multiply by 16 (US)
- • Gal to qt: Multiply by 4
- • Memory aid: 1 gal ≈ 4 L (close estimate)
Common Mistakes
- • Confusing US and UK gallons in calculations
- • Forgetting temperature effects on water weight
- • Using dry gallon instead of liquid gallon
- • Mixing metric and imperial in same calculation
- • Not accounting for container weight in shipping