Converting tank volume between litres and gallons takes just seconds:
Choose your conversion direction
Click "Litres → Gallons" to go from metric to US units, or "Gallons → Litres" to go the other way. The input field label updates automatically.
Select your input unit
Choose litres (L), millilitres (mL), or cubic metres (m³) from the unit dropdown. The converter handles all three automatically — no manual pre-conversion needed.
Enter your volume value
Type your tank's volume. Results calculate instantly as you type, so there's no waiting or manual math.
Read all your converted values
The results panel shows US gallons, litres, cubic metres, cubic feet, cubic inches, and water weight in kg and lbs — every unit you could need for tank sizing, ordering, or documentation.
Tip: The US liquid gallon is the gallon used in the United States for water tanks, fuel storage and household containers. The UK and some Commonwealth countries use the larger imperial gallon, and Canada now sells by the litre — so check which gallon a label means. This converter uses the exact US gallon, 3.785411784 litres.
📐 The Formula
Liters to Gallons Conversion Formula
The formula is a simple division based on the NIST-defined exact value:
Litres to US Gallons: US gal = Litres ÷ 3.78541 US Gallons to Litres: L = US gal × 3.78541
This conversion factor is exact. The US liquid gallon is defined as exactly 231 cubic inches, and since the inch is exactly 2.54 cm, that makes it exactly 3.785411784 litres (NIST SP 811). It is the gallon used throughout the United States for tanks, drums and containers. A handy companion figure: 1 cubic foot holds 7.48 US gallons.
Complete Liters to Gallons Reference Table
Litres
US Gallons
Cubic Metres
100 L
26.42 gal
0.100 m³
250 L
66.04 gal
0.250 m³
500 L
132.09 gal
0.500 m³
1,000 L
264.17 gal
1.000 m³
2,000 L
528.34 gal
2.000 m³
5,000 L
1,320.86 gal
5.000 m³
10,000 L
2,641.72 gal
10.000 m³
25,000 L
6,604.30 gal
25.000 m³
Water Weight from Volume
Once you have the litre value, water weight is straightforward — 1 litre of fresh water weighs almost exactly 1 kg at 4 °C (the temperature of maximum density). At room temperature it is about 0.2–0.3% lighter (0.998 kg at 20 °C), which is why 1 kg per litre is the standard rounding:
This converter is useful across a wide range of everyday and professional scenarios where metric and US volume units mix:
🏠
Household Water Tanks
Many rooftop and underground tanks are sold in litres in metric countries but installed with gallon-rated pumps and fittings imported from the US. Converting between the two avoids under- or over-sizing.
🌧️
Rainwater Harvesting
Rainfall data is often cited in mm, catch calculations are in litres, but storage tanks in some regions are labelled in gallons. This tool bridges all three systems seamlessly.
🚜
Agricultural & Irrigation
Irrigation schedules may specify water in gallons per acre while local suppliers quote tank sizes in litres. Accurate conversion prevents crop stress from under-watering and waste from over-filling.
⛽
Fuel & Chemical Storage
Industrial chemical tanks and fuel storage vessels are often specified in litres by overseas manufacturers, while US procurement and safety documentation uses gallons. Accurate conversion is essential for compliance.
🏗️
Construction & Engineering
Structural load calculations require knowing water weight. This converter outputs kg and lbs alongside the volume conversion so civil engineers can check rooftop or floor load limits instantly.
🚢
Marine & Shipping
Ballast water, freshwater tanks, and fuel bunkering on vessels frequently mix metric and US standards. A fast, reliable converter prevents costly errors in vessel load calculations.
🧮 Worked Example
Worked example: a 1,000-litre IBC tote in gallons
Intermediate bulk containers (IBC totes) are sold worldwide by their 1,000-litre capacity. How much is that in US terms?
Volume: 1,000 ÷ 3.785411784 = 264.17 US gallons (35.31 ft³).
Water weight: 1,000 kg = about 2,205 lb — plus roughly 130 lb for the empty tote and cage.
In UK gallons it would be 219.97 — a label that just says "220 gallons" means imperial gallons.
Mental check: 1,000 ÷ 3.8 ≈ 263 — within half a percent.
❓ FAQ
Frequently Asked Questions
How many gallons is 1000 liters?
1,000 litres equals 264.17 US gallons. This is calculated by dividing the litre value by the exact US gallon conversion factor of 3.78541. Use the calculator above to convert any litre value instantly.
How do I convert liters to gallons for a water tank without a calculator?
For a quick mental estimate, divide the litre value by 3.8 to get approximate US gallons. For example, a 2,000-litre tank ÷ 3.8 ≈ 526 US gallons (exact: 528.3). This is accurate to about 0.5%, which is close enough for most rough estimates. Use this converter when you need exact values.
Is a litre the same as a liter?
Yes — "litre" (British/international spelling) and "liter" (American English spelling) are the same unit of volume. Both equal exactly 1,000 millilitres, or 0.001 cubic metres. The SI symbol is L (uppercase) or l (lowercase). This converter accepts both — just enter your value and get your answer.
How many liters is a 55-gallon drum?
A standard 55-gallon drum holds 208.20 litres. These drums are very common in industrial and agricultural settings across the US. Use this converter's "Gallons → Litres" direction to convert any drum or vessel size instantly.
What is the liters to gallons conversion factor for a water tank calculator?
The exact, NIST-defined conversion factor is: 1 US gallon = 3.785411784 litres (commonly rounded to 3.78541). To go from litres to US gallons, divide by 3.78541. To go from US gallons to litres, multiply by 3.78541. This converter applies the exact factor so your results are precise to five decimal places.
How much does 1000 liters of water weigh in pounds?
1,000 litres of fresh water weighs 1,000 kg (1 metric tonne), which equals 2,204.62 lbs. This is a key figure for structural engineers checking whether a rooftop or floor can support a full tank. If you're calculating load capacity, our Water Tank Weight Calculator also accounts for the empty tank's own weight.
✅ Sources & Review
Sources and review
The conversion factors on this page are exact legal definitions, from these references:
USGS Water Science School — Water Density: about 1 kg per litre (62.4 lb/ft³, 8.34 lb per US gallon).
Reviewed by John Mac, PE, Water Systems Specialist
Texas-licensed Professional Engineer with 13+ years in residential water storage and 180+ tank projects. John writes and reviews every calculator on this site.
