Roof measurement
Rain barrel yield calculator
Estimate rain barrel yield. Homeowner wants collection estimate.
Try the calculation
Estimate collected water before storage losses.
Adjustable example. Change these illustrative inputs to match your task, then recalculate. Reset restores the example and its result.
Understand the result
How this calculation works
Rain barrel yield uses the same catchment arithmetic for potential collected water.
Steps
- Enter catchment area, rainfall depth and runoff coefficient.
- Treat the result as potential volume for the event.
The form starts with the worked example below. Change its values and selections to match your task; Reset restores the example.
Formula
potential gallons = area × rain × coefficient × 0.623.
Variables and units
- Catchment area (sq ft)
- Required. Use a positive value. Starting example: 800. Replace it for your task.
- Rainfall depth (in)
- Required. Zero is accepted. Starting example: 0.75. Replace it for your task.
- Runoff coefficient (ratio)
- Required. Zero is accepted. Starting example: 0.9. Replace it for your task.
What the result means
The page does not model barrel capacity, first flush, overflow or storage timing.
Worked example
Inputs: Catchment area = 800; Rainfall depth = 0.75; Runoff coefficient = 0.9.
Calculation: 800 sq ft × 0.75 in × 0.9 × 0.623 = 336.42 gallons.
Result: 336.42 gallons.
Frequently asked questions
Does it tell me barrel size?
No, compare the potential volume with a selected storage plan separately.
Can a coefficient be zero?
Yes, the form allows a zero assumption.
Does every gallon reach the barrel?
No, the result is a potential volume under the stated coefficient.