Gallons to Pounds

Liquid Fluid Metrology & ASTM Density Standards

The weight of 1 gallon of liquid is governed by its specific gravity. Liquids less dense than water (gasoline, propane) weigh significantly less per gallon, while dense liquids (honey, DEF) weigh more.

Primary Fluid Weights per 1 US Gallon (20^)

• Fresh Water (62^): 8.345 lbs / gal = 3.785 kg

• Whole Milk: 8.596 lbs / gal = 3.899 kg

• Diesel Fuel #2: 7.094 lbs / gal = 3.218 kg

• Automotive Gasoline: 6.176 lbs / gal = 2.801 kg

• Vegetable / Olive Oil: 7.678 lbs / gal = 3.483 kg

• Motor Oil (10W-30): 7.344 lbs / gal = 3.331 kg

• Honey: 11.850 lbs / gal = 5.375 kg

• Liquid Propane (LPG): 4.240 lbs / gal = 1.923 kg

• Diesel Exhaust Fluid (DEF): 9.088 lbs / gal = 4.122 kg

Primary Equations

• Pounds (lbs) = Gallons × Density

• Gallons = Pounds (lbs)Density

How to Use This Calculator

Enter your Volume / Weight Amount to Convert (e.g. 50.0), Fluid Type & Density — choose from Fresh Water (8.345 lbs / US gal), Gasoline / Petrol (6.176 lbs / US gal), Diesel Fuel (7.094 lbs / US gal), Gallon Standard — choose from US Liquid Gallon (231 cu in), UK Imperial Gallon (277.42 cu in), and Conversion Direction — choose from Gallons to Pounds (gal → lbs), Pounds to Gallons (lbs → gal). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Formula Reference: Gallons to Pounds

Input variables:

amountValue — Volume / Weight Amount to Convert

fluidSelect — Fluid Type & Density

gallonStandardSelect — Gallon Standard

conversionDirectionSelect — Conversion Direction

Computed outputs:

convertedAmount — Converted Amount

equivalentPounds — Weight in Pounds (lbs)

equivalentGallons — Volume in Gallons (gal)

equivalentKilograms — Mass in Kilograms (kg)

equivalentMetricTons — Mass in Metric Tons (t)

Mathematical relationships extracted from calculation logic:

lbsPerGal = std === 'uk_imperial' ? (item.usLbs * imperialFactor) : item.usLbs

lbs = val * lbsPerGal

kg = lbs * 0.45359237

metricTons = kg / 1000.0

liters = gal * litersPerGal

Reference constants:

imperialFactor = 1.2009499

Standard: NIST Handbook 44 and BIPM SI unit definitions

Worked Example

Filling a 50-gallon RV fresh water holding tank adds exactly 417.3 pounds (189.3 kg) of cargo weight against the vehicle's payload capacity.

Understanding Your Result

Unit conversion precision: round to the same number of significant figures as your original measurement. Converting 6 feet to meters gives 1.8288 m — but if your measurement was approximate (±1 inch), expressing more than 2 decimal places is false precision. For international trade and technical specifications, SI units (meters, kilograms, liters) are the standard. US customary units (feet, pounds, gallons) differ from Imperial UK units: 1 US gallon = 3.785 L vs. 1 UK gallon = 4.546 L.