Calculate the volume of water produced by rainfall over a selected area. Enter rainfall depth and area to estimate gallons, liters, cubic feet, cubic meters, acre-feet, and collectable runoff volume.
Rainfall depth:
Enter how deep the rainfall was, such as 1 inch, 25 millimeters, or 0.1 feet.
Surface area:
Enter the area the rain falls on, such as a roof, yard, field, driveway, garden, or patio.
Collection efficiency:
Use this to account for losses from gutters, splash, overflow, runoff, evaporation, or soil absorption.
Volume result:
The calculator converts rainfall volume into gallons, liters, cubic feet, cubic meters, and acre-feet.
A rainfall volume calculator is useful for rainwater harvesting, rain barrels, cistern sizing, stormwater planning, drainage checks, garden watering, lawn care, agriculture, roofing, and landscape planning.
Actual collected water can vary based on roof shape, surface material, gutters, slope, soil saturation, drainage, wind, and how fast the rain falls.
Your result shows the total volume of rain that fell over the selected area. The collected volume applies the collection efficiency percentage to estimate how much water may actually be captured, drained, or usable.
Multiply rainfall depth by the surface area. Then convert the result into gallons, liters, cubic feet, or cubic meters.
One inch of rain over 1,000 square feet is about 623 gallons before collection losses.
Collection efficiency estimates the percentage of rainfall volume that is actually captured or usable after losses.
Yes. Enter your roof collection area, rainfall depth, and collection efficiency to estimate how many gallons may reach the rain barrel.