Load summary
Use this section when the water weight has to become a real-world load: an aquarium on a stand, a water tank on a platform, a pool on the ground, a trailer hauling water, or bottled water stacked for storage. The original calculator above still gives the water-only weight; this summary adds container weight, extra materials, and a planning margin.
Enter a volume above to create a planning load summary.
Quick water weight answers
These common answers use practical everyday estimates. Exact mass changes slightly with water temperature, salinity, measurement standard, and container weight.
A full 500 mL plastic bottle weighs a little more after adding the bottle, cap, and label.
This is water only. For tank and trailer details, use the 500 Gallons Water Weight Calculator.
This refers to a US liquid gallon of fresh water.
This is the easiest metric water conversion for everyday use.
Useful for tanks, pools, construction estimates, and volume calculations.
For example, 100 gallons of water weighs about 834 pounds.
Water Weight Answer Hub
This page is the main hub for water weight questions. Start with the calculator, use the quick answer blocks for common searches, then move to a specific scenario if you are planning a pool, aquarium, water tank, bottle case, or large container.
What to check after you calculate water weight
The number matters because water is often carried by something else. Use these checks before placing, hauling, stacking, or building around a water load.
Aquarium
- Tank glass or acrylic weight
- Stand rating and level surface
- Substrate, rocks, decorations, filters, lid, and lights
- Floor support under large tanks
Water tank
- Dry tank weight
- Frame, fittings, pump, hoses, and platform
- Slab, rack, trailer, or stand rating
- Refill and maintenance access
Swimming pool
- Pool structure and equipment
- Ground surface and leveling
- People and moving water
- Do not use this as deck approval
Trailer or pickup
- Payload rating
- Axle rating, hitch rating, and tongue weight
- Tank securement and water movement
- Braking distance when loaded
Bottled water
- Bottle, case, wrap, tray, and pallet weight
- Shelf, cart, elevator, and vehicle limits
- Delivery and storage route
- Stacking height and handling limits
Shelves and racks
- Rated load per shelf or bay
- Weight distribution
- Floor contact points
- Safety margin for repeated use
Common water weight chart
This compact chart covers the most common volumes. The larger tables below remain in place for gallons, liters, milliliters, and cubic feet.
| Volume | Approx. pounds | Approx. kilograms | Next thing to check |
|---|---|---|---|
| 1 US gallon | 8.34 lb | 3.79 kg | Jug or small container |
| 5 US gallons | 41.7 lb | 18.9 kg | Bucket, cooler jug, shelf, cart |
| 50 US gallons | 417 lb | 189 kg | Aquarium stand or barrel support |
| 100 US gallons | 834 lb | 378 kg | Tank, rack, floor, trailer |
| 500 US gallons | 4,170 lb | 1,891 kg | Tank shell, trailer, vehicle payload |
| 1,000 US gallons | 8,340 lb | 3,783 kg | Storage tank, slab, delivery planning |
| 1 liter | 2.20 lb | 1.00 kg | Bottle or small container |
| 1 cubic foot | 62.4 lb | 28.3 kg | Tank, pool, construction estimate |
Water weight tables
Use these tables for fast answers without entering values into the calculator.
Gallons to pounds of water
| US gallons | Approx. pounds | Approx. kilograms | Common use |
|---|---|---|---|
| 1 gallon | 8.34 lb | 3.79 kg | Single jug / small container |
| 5 gallons | 41.7 lb | 18.9 kg | Water cooler jug |
| 10 gallons | 83.4 lb | 37.9 kg | Small tank / aquarium |
| 25 gallons | 208.5 lb | 94.6 kg | Medium aquarium / container |
| 50 gallons | 417 lb | 189 kg | Large aquarium / barrel |
| 100 gallons | 834 lb | 378 kg | Stock tank / storage |
| 250 gallons | 2,085 lb | 946 kg | Water tank / trailer |
| 500 gallons | 4,170 lb | 1,891 kg | Large tank / trailer |
| 1,000 gallons | 8,340 lb | 3,783 kg | Pool / storage tank |
mL and liters to water weight
| Volume | Approx. grams | Approx. kilograms | Approx. pounds |
|---|---|---|---|
| 100 mL | 100 g | 0.10 kg | 0.22 lb |
| 250 mL | 250 g | 0.25 kg | 0.55 lb |
| 500 mL | 500 g | 0.50 kg | 1.10 lb |
| 750 mL | 750 g | 0.75 kg | 1.65 lb |
| 1 liter | 1,000 g | 1 kg | 2.20 lb |
| 2 liters | 2,000 g | 2 kg | 4.41 lb |
| 10 liters | 10,000 g | 10 kg | 22.05 lb |
Cubic feet to water weight
| Cubic feet | Approx. pounds | Approx. kilograms |
|---|---|---|
| 1 ft³ | 62.4 lb | 28.3 kg |
| 5 ft³ | 312 lb | 141.5 kg |
| 10 ft³ | 624 lb | 283 kg |
| 25 ft³ | 1,560 lb | 708 kg |
| 50 ft³ | 3,120 lb | 1,415 kg |
| 100 ft³ | 6,240 lb | 2,830 kg |
Water weight use cases
500 mL bottles and bottled water cases
500 mL of water weighs about 500 grams, 0.5 kilograms, 1.10 pounds, or 17.64 ounces. A full bottle is slightly heavier because plastic packaging, the cap, and the label add extra weight. A 24-pack or 40-pack should also include the tray, shrink wrap, and case packaging. For the direct 500 mL answer, use the dedicated 500 mL Water Weight Calculator. For bottle count, case weight, and pallet planning, use the Bottled Water Weight Calculator.
Water tanks, trailers, rain barrels, and IBC totes
For tanks and trailers, the water load is often the largest part of the total weight. A 500-gallon water load is already about 4,170 pounds before adding the dry weight of the tank, trailer, frame, fittings, pump, or hoses. For a scenario-specific estimate, use the dedicated Water Tank Weight Calculator.
Aquarium water weight
Aquarium water weight is only one part of total aquarium load. Add the tank material, substrate, rocks, decorations, water displacement, filters, lights, stand, and safety margin when deciding whether furniture or flooring can support a fish tank. For tank dimensions, gallons, and optional total load, use the dedicated Aquarium Water Weight Calculator.
Swimming pool water weight
Swimming pools can hold thousands of gallons. A 10,000-gallon pool contains about 83,400 pounds of water. For pool shape, depth, gallons, and tons, use the dedicated Swimming Pool Water Weight Calculator.
Formula used by this calculator
The calculator converts your selected volume into milliliters, multiplies by an approximate water density, then converts grams into pounds, kilograms, and ounces.
mass = volume × density
pounds ≈ grams × 0.00220462
gallons to pounds of water ≈ gallons × 8.34
cubic feet to pounds of water ≈ cubic feet × 62.4
For dedicated unit pages, use the Gallons to Pounds Water Calculator or the Cubic Feet Water Weight Calculator.
For everyday answers, the simple metric rule works well: 1 mL of water is about 1 gram, and 1 liter of water is about 1 kilogram. Exact scientific values vary slightly with temperature and dissolved minerals.
Water weight FAQ
Does 500 mL of water weigh exactly 500 grams?
For everyday use, yes: 500 mL of fresh water is about 500 grams. Strictly speaking, the exact mass changes slightly with temperature and purity, but 500 g is the practical answer most people need.
How much does 500 mL of water weigh in pounds?
500 mL of water weighs about 1.10 pounds. A full 500 mL plastic bottle will weigh slightly more because the bottle and cap add extra mass.
How much does 500 gallons of water weigh?
500 US gallons of water weighs about 4,170 pounds, or about 1,890 kilograms. For tank, trailer, saltwater, or total load estimates, use the 500 Gallons Water Weight Calculator.
Is saltwater heavier than freshwater?
Yes. Saltwater is denser than freshwater, so the same volume of saltwater weighs slightly more. This calculator includes a simple saltwater estimate for planning, not laboratory measurement.
Does temperature change water weight?
Temperature changes water density. Warm water expands slightly and becomes less dense. For most household, pool, aquarium, and tank planning, the difference is small compared with container weight and safety margin.
Can I use this for aquariums, pools, or storage tanks?
Yes, for the water portion of the weight estimate. For total load, include tank glass or acrylic, pool structure, tank shell, substrate, rocks, filters, pumps, stands, trailers, decking, people, and other equipment. Use the Aquarium Water Weight Calculator, Swimming Pool Water Weight Calculator, Water Tank Weight Calculator, 500 mL Water Weight Calculator, Bottled Water Weight Calculator, Gallons to Pounds Water Calculator, 500 Gallons Water Weight Calculator, 1 Gallon Water Weight Calculator, 5 Gallon Water Weight Calculator, 100 Gallons Water Weight Calculator, 1000 Gallons Water Weight Calculator, Saltwater Weight Calculator, or Cubic Feet Water Weight Calculator for scenario-specific estimates.