Free Rainfall Intensity Calculator
Estimate rainfall intensity from total precipitation depth and storm duration for drainage design.
mm
minutes
Rainfall Intensity
100.0 mm/h
Intensity0.02778 mm/s
Rainfall Intensity vs Storm Duration
Rainfall Intensity
Rainfall intensity is the rate of rainfall, critical for sizing stormwater drainage systems.
Formula
i = P / t
where P is the total depth of rainfall (mm) and t is the duration (hours). Shorter, more intense storms require higher drainage capacity. Design storms are typically characterised by intensity-duration-frequency (IDF) curves.
Example Calculation
50 mm of rain over 30 minutes.
- 01Duration in hours = 30 / 60 = 0.5 h
- 02Intensity = 50 / 0.5 = 100 mm/h
- 03This is a relatively intense rainfall event.
Frequently Asked Questions
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