Gallons to Pounds Converter
Convert between gallons and pounds for water, oil, fuel, milk, and 40+ liquids with precise density calculations
Gallons ↔ Pounds Converter
Density: 8.345 lb/gal (H₂O)
Conversion Results
Common Container Examples
| Container | Capacity | Water Weight | Common Use |
|---|---|---|---|
| 5-Gallon Bucket | 5 gal | 41.7 lbs | Water storage, paint |
| 55-Gallon Drum | 55 gal | 459.0 lbs | Industrial chemicals, oil |
| Gas Tank (Car) | 15 gal | 125.2 lbs | Fuel capacity |
| Milk Jug | 1 gal | 8.3 lbs | Household liquids |
| Swimming Pool (Small) | 10000 gal | 83454.0 lbs | Residential pool |
| Tanker Truck | 8000 gal | 66763.2 lbs | Fuel delivery |
Density Quick Reference
Conversion Tips
Water at room temperature weighs about 8.34 pounds per gallon
Gasoline is lighter than water at about 6.07 pounds per gallon
Temperature affects liquid density - use specific values for accuracy
UK gallons are 20% larger than US gallons
Understanding Volume to Weight Conversion
Why Volume and Weight Differ
Gallons measure volume (space occupied), while pounds measure weight (gravitational force on mass). The relationship between them depends on the liquid's density - how much mass is packed into each gallon.
The Density Formula
Weight (pounds) = Volume (gallons) × Density (lb/gal)
This fundamental relationship allows us to convert between volume and weight for any liquid when we know its density.
Factors Affecting Density
- •Temperature: Most liquids become less dense when heated
- •Pressure: Higher pressure can increase density
- •Composition: Mixtures and solutions have variable densities
- •Dissolved substances: Salt in water increases density
Important: For critical applications (shipping, chemical processing), always verify density values with current specifications and environmental conditions.
Real-World Applications
🚛 Transportation & Shipping
Calculate payload weights for trucks, ships, and aircraft. Critical for safety regulations and fuel efficiency planning.
🏭 Industrial Processing
Batch calculations, storage tank planning, and chemical mixing ratios in manufacturing processes.
🏊 Pool & Spa Maintenance
Determine chemical dosing amounts and understand structural load requirements for pools and hot tubs.
⛽ Fuel Management
Fuel consumption calculations, tank capacity planning, and fuel cost analysis for vehicles and equipment.
🍯 Food & Beverage
Recipe scaling, ingredient purchasing, and nutritional calculations for commercial and home cooking.
🌾 Agriculture
Grain storage calculations, liquid fertilizer applications, and livestock feed planning.
Liquid Density Comparison Chart
Compare the weight of different liquids per gallon to understand their relative densities.
| Liquid Type | Pounds per US Gallon | Relative to Water | 55-Gallon Drum Weight |
|---|---|---|---|
| Propane (Liquid) | 4.24 lbs | 51% lighter | 233 lbs |
| Gasoline (Regular) | 6.07 lbs | 27% lighter | 334 lbs |
| Ethanol | 6.58 lbs | 21% lighter | 362 lbs |
| Kerosene | 6.78 lbs | 19% lighter | 373 lbs |
| Diesel Fuel | 7.09 lbs | 15% lighter | 390 lbs |
| Olive Oil | 7.65 lbs | 8% lighter | 421 lbs |
| Water (Room Temp) | 8.35 lbs | Baseline (100%) | 459 lbs |
| Seawater | 8.56 lbs | 3% heavier | 471 lbs |
| Milk (Whole) | 8.64 lbs | 3% heavier | 475 lbs |
| Antifreeze (50/50) | 8.85 lbs | 6% heavier | 487 lbs |
| Paint (Latex) | 10.20 lbs | 22% heavier | 561 lbs |
| Maple Syrup | 10.98 lbs | 32% heavier | 604 lbs |
| Honey | 11.85 lbs | 42% heavier | 652 lbs |
| Sulfuric Acid (98%) | 15.33 lbs | 84% heavier | 843 lbs |
| Mercury | 113.50 lbs | 1,260% heavier | 6,243 lbs |
Note: Values shown are for standard conditions. Actual density may vary with temperature, pressure, and composition.
How to Calculate Gallons to Pounds (Step-by-Step)
Method 1: Using Known Density
Determine what liquid you're converting (water, gasoline, milk, etc.)
Look up the liquid's density in pounds per gallon (lb/gal). For water, it's 8.345 lb/gal at room temperature.
Weight (lbs) = Volume (gallons) × Density (lb/gal)
Question: How much does 5 gallons of water weigh?
Solution: 5 gallons × 8.345 lb/gal = 41.725 pounds
Method 2: Reverse Calculation (Pounds to Gallons)
Determine the weight in pounds that you want to convert
Look up the liquid's density in pounds per gallon (lb/gal)
Volume (gallons) = Weight (lbs) ÷ Density (lb/gal)
Question: How many gallons is 50 pounds of gasoline?
Solution: 50 pounds ÷ 6.073 lb/gal = 8.23 gallons
Quick Reference Formulas
Use when converting volume to weight
Use when converting weight to volume
How Temperature Affects Weight
Temperature significantly impacts liquid density. As temperature increases, most liquids expand and become less dense, meaning they weigh less per gallon. This is especially important for fuel, chemicals, and precise measurements.
Water Density by Temperature
| Temperature | Density (lb/gal) | 10 Gal Weight |
|---|---|---|
| 32°F (0°C) - Freezing | 8.345 | 83.45 lbs |
| 39°F (4°C) - Maximum Density | 8.345 | 83.45 lbs |
| 68°F (20°C) - Room Temp | 8.345 | 83.45 lbs |
| 100°F (38°C) - Hot Day | 8.288 | 82.88 lbs |
| 212°F (100°C) - Boiling | 7.996 | 79.96 lbs |
Observation: Water at boiling point weighs 4% less than at room temperature.
Gasoline Density by Temperature
| Temperature | Density (lb/gal) | 10 Gal Weight |
|---|---|---|
| 30°F (-1°C) - Cold | 6.163 | 61.63 lbs |
| 60°F (15°C) - Standard | 6.073 | 60.73 lbs |
| 80°F (27°C) - Warm | 6.018 | 60.18 lbs |
| 100°F (38°C) - Hot | 5.962 | 59.62 lbs |
| 120°F (49°C) - Very Hot | 5.907 | 59.07 lbs |
Observation: Gasoline in a hot tank weighs 4% less than in cold conditions.
Temperature Impact on Fuel Sales
Gas stations often sell fuel by volume (gallons). In hot weather, the fuel is less dense, so you're actually getting less energy per gallon. This is why some locations use temperature-compensated pumps that adjust the volume to account for temperature variations, ensuring you get the same amount of fuel energy regardless of temperature.
Frequently Asked Questions
How much does a gallon of water weigh?
A US gallon of water weighs approximately 8.345 pounds (8 lbs 5.5 oz) at room temperature (68°F/20°C). This is the most commonly used reference point for water weight. A UK gallon weighs about 10.02 pounds because it's 20% larger than a US gallon. The exact weight varies slightly with temperature - water is densest at 39°F (4°C) and becomes lighter as it gets warmer or colder from that point.
How many pounds is 5 gallons of water?
Five gallons of water weighs approximately 41.7 pounds (5 gallons × 8.345 lb/gal = 41.725 lbs). This is the weight you'd feel when carrying a standard 5-gallon water jug or bucket. For comparison, this is roughly the weight of a medium-sized dog or five bags of sugar. In metric units, 5 gallons of water equals approximately 18.9 liters and weighs about 18.9 kilograms (41.7 lbs).
How much does a gallon of gasoline weigh?
A gallon of regular gasoline weighs approximately 6.07 pounds at standard temperature (60°F). This is about 27% lighter than water due to gasoline's lower density. Premium gasoline is slightly heavier at about 6.16 pounds per gallon. The weight varies with temperature - gasoline expands when hot and contracts when cold. A full 15-gallon car tank of gasoline weighs roughly 91 pounds (15 × 6.07), which is why fuel efficiency decreases with a full tank compared to an empty one.
How much does a 55-gallon drum of oil weigh?
A 55-gallon drum of motor oil weighs approximately 420 pounds (55 gallons × 7.64 lb/gal = 420 lbs), not including the weight of the drum itself (which adds about 40 pounds for a steel drum). For crude oil, the weight is about 399 pounds (55 × 7.256). The exact weight depends on the type and grade of oil - lighter oils weigh less while heavier oils weigh more. Always account for the drum's weight when calculating total shipping weight or vehicle payload capacity. A full 55-gallon drum of motor oil with the drum weighs approximately 460 pounds total.
Why do different liquids have different weights per gallon?
Different liquids have different weights per gallon because of their varying density - how tightly packed their molecules are. Density depends on molecular composition, structure, and intermolecular forces. For example, gasoline (hydrocarbons) has loosely packed molecules and weighs only 6 lbs/gal, while mercury (a dense metal) has tightly packed atoms and weighs 113.5 lbs/gal. Water sits in the middle at 8.3 lbs/gal. Temperature, pressure, and dissolved substances also affect density. Saltwater is denser than freshwater because dissolved salt adds mass. This principle is why oil floats on water - oil is less dense (lighter per gallon) than water.
How do I convert pounds to gallons for any liquid?
To convert pounds to gallons, divide the weight in pounds by the liquid's density in pounds per gallon: Gallons = Pounds ÷ Density (lb/gal). First, identify your liquid and find its density (you can use our calculator's built-in database of 40+ liquids). For example, if you have 100 pounds of diesel fuel: 100 lbs ÷ 7.094 lb/gal = 14.1 gallons. For water: 100 lbs ÷ 8.345 lb/gal = 12.0 gallons. If you don't know the exact density, you can often find it on the product's Safety Data Sheet (SDS) or technical specifications. Remember that temperature affects density, so use values appropriate for your conditions.
What's the difference between US gallons and UK gallons?
US gallons and UK (Imperial) gallons are different measurement systems. A US gallon equals 3.785 liters, while a UK gallon equals 4.546 liters - making the UK gallon about 20% larger. For water weight: 1 US gallon = 8.345 lbs, while 1 UK gallon = 10.02 lbs. The US also has a "dry gallon" (4.405 liters) used for agricultural products like grain and produce, though it's rarely used today. When doing international conversions, always specify which gallon type you're using. Fuel economy figures differ significantly: a car getting 30 US MPG would get about 36 UK MPG because UK gallons are larger.
How much does milk weigh per gallon?
Whole milk (3.25% fat) weighs approximately 8.637 pounds per gallon, making it slightly heavier than water at 8.345 pounds per gallon. This extra weight comes from dissolved proteins, fats, sugars (lactose), and minerals. Skim milk weighs about 8.612 pounds per gallon - slightly less than whole milk because fat has been removed, but still heavier than water. A gallon jug of milk at the grocery store weighs about 8.9-9.0 pounds including the plastic jug (which weighs about 0.25 pounds). Heavy cream weighs less than milk at about 8.5 lbs/gal, while half-and-half weighs approximately 8.56 lbs/gal.
Does temperature really affect liquid weight that much?
Yes, temperature significantly affects liquid density and weight. As temperature increases, most liquids expand and become less dense, meaning they weigh less per gallon. For water, the difference between freezing (32°F) and boiling (212°F) is about 4% - from 8.345 to 7.996 lbs/gal. For gasoline, the difference between cold (30°F) and hot (120°F) conditions is also about 4% - from 6.163 to 5.907 lbs/gal. This matters for several reasons: (1) Fuel delivery - gasoline delivered in summer weighs less and contains less energy; (2) Chemical manufacturing - precise recipes require temperature compensation; (3) Shipping - payload calculations must account for temperature variations. Professional measurements often specify a standard temperature (usually 60°F for petroleum products) to ensure consistency.
Can I use this calculator for agricultural products like grain?
Yes, our calculator includes several agricultural products (corn, soybeans, wheat), but keep in mind that these are approximations. Agricultural products present unique challenges: (1) Moisture content - wet grain weighs more than dry grain; (2) Kernel size variation - how tightly kernels pack affects density;(3) Temperature and humidity - affect both weight and volume. For corn, wet shelled corn weighs about 6.01 lbs/gal while dry corn weighs 5.8 lbs/gal. Soybeans average 6.25 lbs/gal and wheat about 6.4 lbs/gal. For critical agricultural applications (crop insurance, sales contracts, storage calculations), always use official USDA test weights and measure moisture content. The US dry gallon (4.405 liters) was historically used for grain but has largely been replaced by bushel measurements.
Industry-Specific Applications
🚚 Trucking & Logistics
- •Payload calculations: Determine if load is within legal weight limits (80,000 lbs gross vehicle weight in US)
- •Fuel planning: Calculate weight of diesel for trip planning (full tank adds 600+ lbs)
- •Tanker loading: Ensure liquid cargo doesn't exceed axle weight limits
- •Example: 8,000-gallon gasoline tanker weighs 48,584 lbs (8,000 × 6.073) plus truck weight
🏭 Chemical Manufacturing
- •Batch formulation: Precise weight measurements for chemical reactions
- •Storage planning: Determine floor load capacity for chemical tanks
- •Safety compliance: Calculate containment requirements for spill prevention
- •Example: 55-gallon drum of sulfuric acid weighs 843 lbs - requires special handling
✈️ Aviation & Aerospace
- •Fuel weight calculations: Critical for takeoff weight and center of gravity
- •Jet fuel (Jet A): Weighs 6.71 lbs/gal at standard temperature
- •Altitude effects: Temperature at altitude affects fuel density significantly
- •Example: Boeing 747 holds 57,285 gallons = 384,443 lbs of jet fuel at full capacity
🏗️ Construction & Building
- •Floor load calculations: Determine if floor can support water tanks or chemical storage
- •Paint estimation: Calculate weight for shipping and scaffold loading
- •Concrete additives: Weight calculations for admixtures and water content
- •Example: 500-gallon water tank on a roof weighs 4,172 lbs - requires structural engineering
🍷 Food & Beverage Industry
- •Recipe scaling: Convert volume-based recipes to weight for consistency
- •Shipping calculations: Determine freight costs for liquids like juice, wine, milk
- •Storage planning: Calculate cold storage weight limits for beverages
- •Example: 1,000-gallon wine tank weighs 8,270 lbs (wine is slightly denser than water)
⚡ Energy & Utilities
- •Fuel oil delivery: Calculate heating oil weight for residential and commercial delivery
- •Propane distribution: Determine truck capacity for liquid propane (4.24 lbs/gal)
- •Coolant systems: Calculate antifreeze weight for large HVAC systems
- •Example: 500-gallon home heating oil tank contains 3,605 lbs of fuel oil