Estimate pond acre-feet and gallons from surface area (acres or length×width) and average depth.
Use this for livestock water budgets, irrigation storage sketches, or comparing dugout sizes before you call a pond builder.
Average depth matters more than maximum depth — measure several points or use builder as-built grades. One acre-foot ≈ 325,851 gallons.
Acre-feet = surface acres × average depth. Gallons = acre-feet × 325,851. Rectangle acres = L×W÷43,560.
acres = L × W ÷ 43,560 (rectangle mode)
acre_ft = acres × avg_depth_ft
gallons = acre_ft × 325,851
1.5 acres at 8 ft average depth → 12 acre-feet ≈ 3.91 million gallons.
Assumptions: average depth represents the full pond; banks are included in surface acres.
Limits: irregular shorelines and wedge shapes need more survey points; seepage/evaporation not modeled.
Responsibility: dam safety and water rights rules vary — use local engineers for construction.
Volume uses average depth across the basin. A 15 ft hole with shallow shelves is not 15 ft average.
Not all volume is pumpable — leave reserve for drought and sediment. Pair with livestock water needs.
Estimate acres from πr²÷43,560, then enter that acreage in surface-acres mode.