Rainfall Accumulation Calculator
Enter multiple rainfall readings in inches or millimeters to instantly calculate cumulative totals, averages, and event summaries.
Use the Rainfall Accumulation Calculator
Add Rainfall Reading
Unit:
inches
in
Load sample data:
Total
0.00
in
Average
—
in
Max Event
—
in
Readings
0
events
Readings Log
No readings yet. Add your first entry on the left.
| # | Label | Amount | Cumulative |
|---|
Quick Reference
1 in = 25.4 mm
1 mm = 0.0394 in
Summary
The Rainfall Accumulation Calculator lets you log multiple storm events or daily rain gauge readings and instantly computes the cumulative total, average per event, maximum single event, and total event count. Works entirely in your browser with no data sent to any server.
How it works
- Choose your preferred unit — inches or millimeters.
- Enter a label (optional) and the rainfall amount for each reading.
- Click "Add Reading" to append it to your session log.
- The summary panel updates in real time showing total, average, max, and count.
- Use the trash icon to delete any individual entry, or "Clear All" to start fresh.
- Switch units at any time — all values convert automatically.
Use cases
- Summing daily rain gauge readings across a week or month.
- Totaling rainfall from multiple storm cells during a weather event.
- Comparing average precipitation across different time periods.
- Tracking irrigation input alongside natural rainfall for agriculture.
- Calculating total inches from a series of NOAA daily reports.
- Logging seasonal snowmelt-equivalent rainfall data.
- Verifying rain gauge sensor data against manual readings.
- Building a quick field record during storm spotting activities.
Frequently Asked Questions
Last updated: 2026-06-11 · Reviewed by Nham Vu