Impervious Surface Runoff Calculator
Stormwater runoff volume from an impervious area for a rainfall depth.
Compare Your Options And Get Clear Answers
Stormwater runoff volume from an impervious area for a rainfall depth.
Impervious Surface Runoff Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Results update as you change the inputs.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Impervious Quick Guide
Typical values for reference.
| Area sq ft | Rain in | C | Runoff |
|---|---|---|---|
| 3600 | 1 | 0.9 | 2,020 gallons |
| 1000 | 0.5 | 0.9 | 281 gallons |
| 10000 | 2 | 0.85 | 10,597 gallons |
| 2500 | 1.2 | 0.7 | 1,309 gallons |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Impervious Surface Runoff Calculator FAQ
Answers to common questions about this calculator.
It uses the formula shown with your inputs. Real prices and rules vary, so treat it as a guide.
Volume = area x rain x coefficient.
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.
Yes. Replace each input with your own figures and the result updates instantly.