Gallons per Square Foot Calculator
How it Works
01Pick Mode
Volume (ponds, pools, tanks) or Coverage (paint, sealer, stain).
02Enter Area
Rectangle (L×W), circle (diameter), or direct area in ft².
03Set Depth or Rate
Inches for Volume mode, coating type + coats for Coverage mode.
04Get Gallons
Gallons, liters, cubic feet + formula breakdown.
What is a Gallons per Square Foot Calculator?
The Gallons per Square Foot Calculator answers a dozen common water and coverage questions in one place: how many gallons in a cubic foot (7.48), how many gallons in a 24 round pool (~13,600 at 4 ft), how many gallons is the average pool (~18,000), and how many gallons of sealer or paint to cover an area.
Two modes: Volume for pools, ponds, fish tanks, and cylindrical water features; Coverage for driveway sealers, concrete sealer, latex paint, deck stain, and 5 other coating types at manufacturer-typical ft²/gal rates. Three shape options (rectangle, circle, direct area) cover any pool, tank, or project.
Built on the universal conversion 1 ft³ = 7.48052 US gallons. 100% free, in-browser, no signup.
How the Gallons Calculator Works
The Gallons Formula
VOLUME MODE: Gallons = Area (ft²) × Depth (in) ÷ 12 × 7.48052 COVERAGE MODE: Gallons = Area (ft²) ÷ Coverage (ft²/gal) × Number of CoatsKey constants:
- 1 ft³ = 7.48052 US gallons (the core conversion)
- 1 US gallon = 3.78541 liters
- 1 ft³ = 28.3168 liters
- 1 inch = 1/12 foot (depth converted to feet before multiplying)
Calculation In Practice
Volume example — 10×20 ft pond at 2 ft depth:
- Area = 10 × 20 = 200 ft²
- Depth = 2 ft (24 inches)
- Volume = 200 × 2 = 400 ft³
- Gallons = 400 × 7.48052 = 2,992 US gal ≈ 11,326 liters
Coverage example — 1,500 ft² driveway, 2 coats sealer at 400 ft²/gal:
- Base = 1,500 ÷ 400 = 3.75 gal per coat
- Total = 3.75 × 2 coats = 7.5 US gal
How Many Gallons in a Cubic Foot of Water?
1 cubic foot of water = 7.48052 US gallons. That's the core conversion powering this tool. Useful derived facts:
- 1 cubic foot of water weighs 62.4 lb (at 39°F)
- 1 cubic yard of water = 27 ft³ = 202 gallons
- 1 cubic meter of water = 264.17 gallons (or 1,000 liters)
- 1 US gallon of water = 0.1337 ft³ = 8.34 lb
In metric: 1 liter = 1 kg, 1 m³ = 1,000 kg. The US gallon system is based on fluid volume, not weight, but this chart lets you translate quickly.
For any irregular volume, convert to cubic feet first (length × width × depth in feet), then multiply by 7.48 to get US gallons.
Swimming Pool Volume — How Many Gallons Is Your Pool?
Pool gallons depend on shape and depth. Use our calculator with the right shape, or refer to these common-size estimates:
| Pool | Dimensions | Avg Depth | Gallons |
|---|---|---|---|
| 12 ft round | 113 ft² | 3.0 ft | ~2,543 |
| 15 ft round | 177 ft² | 4.0 ft | ~5,290 |
| 18 ft round | 254 ft² | 4.0 ft | ~7,617 |
| 21 ft round | 346 ft² | 4.0 ft | ~10,356 |
| 24 ft round | 452 ft² | 4.0 ft | ~13,594 |
| 24 ft round | 452 ft² | 4.5 ft | ~15,293 |
| 27 ft round | 573 ft² | 4.0 ft | ~17,205 |
| 12×24 rect | 288 ft² | 5.0 ft | ~10,771 |
| 16×32 rect | 512 ft² | 5.0 ft | ~19,155 |
| 20×40 rect | 800 ft² | 5.5 ft | ~32,923 |
Average US backyard pool: 18,000–20,000 gallons (in-ground). Above-ground round pools average 7,000–13,000. Hot tubs / spas: 300–500. Lap pools: 5,000–25,000 depending on length.
For uneven depth (shallow + deep end), use average depth = (shallow + deep) ÷ 2. Enter that in our calculator for a pool-accurate number.
24 ft Round Pool Gallons — Exact Volumes by Depth
The 24 ft round above-ground pool is one of the most popular sizes sold in the US. Common depths and exact gallons:
- 24 ft × 3.0 ft deep — 10,196 gallons (kiddie / shallow)
- 24 ft × 3.5 ft deep — 11,895 gallons
- 24 ft × 4.0 ft deep — 13,594 gallons (most common above-ground)
- 24 ft × 4.5 ft deep — 15,293 gallons (standard 52-inch wall with ~6 in freeboard)
- 24 ft × 5.0 ft deep — 16,992 gallons (maximum for most 24 ft round pools)
Formula: π × (12)² × depth × 7.48 = 452.39 × depth × 7.48 ≈ depth × 3,384 gallons.
Chemistry dosing: 1 oz granular shock per 10,000 gallons, 1 lb stabilizer per 5,000 gallons for initial startup. Knowing your pool's exact gallons is critical for safe chlorine levels.
Fish Tank / Aquarium Volume Reference
Fish tank sizes are rated by US liquid gallons, but the actual water volume is 5–15% less after substrate, decor, and the empty freeboard below the rim. Reference table:
| Tank | Dimensions (L×W×H) | Rated Gallons | Actual Water |
|---|---|---|---|
| Nano | 8×8×10 in | 2–3 gal | ~2.5 gal |
| Small | 20×10×12 in | 10 gal | ~9 gal |
| Community | 24×12×16 in | 20 gal | ~18 gal |
| Mid | 36×12×16 in | 30 gal | ~27 gal |
| Standard | 36×18×19 in | 50 gal | ~45 gal |
| Large | 48×18×20 in | 75 gal | ~68 gal |
| XL | 72×18×20 in | 100 gal | ~92 gal |
Formula for any rectangular tank: length × width × height (in inches) ÷ 231 = US gallons. 1 US gallon = 231 cubic inches. Use the Volume mode in the calculator above for any custom aquarium dimensions.
Cubic Foot ↔ Gallon Cheat Sheet
Quick conversion reference — the number 7.48 is the key. Memorize it and you can convert any volume.
| From | To | Factor |
|---|---|---|
| Cubic Feet | US Gallons | × 7.48052 |
| Cubic Yards | US Gallons | × 201.974 |
| Cubic Meters | US Gallons | × 264.172 |
| Cubic Inches | US Gallons | ÷ 231 |
| Liters | US Gallons | ÷ 3.785 |
| Imperial Gallons (UK) | US Gallons | × 1.2009 |
| US Gallons | Cubic Feet | × 0.13368 |
| US Gallons | Liters | × 3.78541 |
| US Gallons | Ounces (fluid) | × 128 |
| US Gallons | Quarts | × 4 |
| US Gallons | Pints | × 8 |
| US Gallons | Cups | × 16 |
Common quick answers: 1 cup = 8 fl oz = 0.0625 gal. 1 pint = 16 fl oz = 0.125 gal. 1 quart = 32 fl oz = 0.25 gal. 1 gallon = 128 fl oz = 4 quarts = 8 pints = 16 cups = 3.785 liters.
Who Should Use This Tool?
Technical Reference
Volume constants: 1 ft³ = 7.48052 US gal = 28.3168 L. 1 US gal = 3.78541 L = 0.133681 ft³.
Supported coating presets (ft²/gal typical):
- Driveway Sealer (asphalt) — 400, 2 coats
- Concrete Sealer — 275, 2 coats
- Latex Paint (walls) — 350, 2 coats
- Oil-Based Paint — 325, 2 coats
- Deck Stain (semi-transparent) — 250, 1 coat
- Solid Deck Stain — 200, 2 coats
- Pool Paint (epoxy) — 225, 2 coats
- Garage Floor Epoxy — 300, 2 coats
- Primer — 400, 1 coat
Coverage rates are manufacturer-typical. Actual coverage varies significantly by surface porosity, texture, and application method — always check the product datasheet.
Key Takeaways
The magic number is 7.48052 — the number of US gallons in one cubic foot. Everything else is geometry: figure out the area, figure out the depth (or coverage rate), multiply, done.
For volume projects, always buy 5–10% extra liquid to account for topping off. For coverage projects, factor in primer separately if your coating requires it — primer usually covers 400+ ft²/gal and counts as an extra coat.
Frequently Asked Questions
How many gallons are in a cubic foot of water?
How many gallons of water in a swimming pool?
How many gallons is the average pool?
How many gallons in a 24 round pool?
How many gallons is a 50 gallon fish tank?
How do I calculate pool gallons?
How many gallons in a cubic foot?
What is the volume of a cylinder in gallons?
How many gallons of water in a 12×24 pool?
Is this calculator free?
Author Spotlight
The ToolsACE Team
Our specialized research and development team at ToolsACE brings together decades of collective experience in construction estimating, material coverage data, and high-performance web tools.
Disclaimer
Coverage rates are manufacturer-typical estimates. Actual coverage varies by surface texture, porosity, and application method. Always consult the product datasheet for your specific coating.