Rainfall Accumulation Calculator

Summary

Enter multiple rainfall readings in inches or millimeters to instantly calculate cumulative totals, averages, and event summaries.

How it works

1. Choose your preferred unit — inches or millimeters.
2. Enter a label (optional) and the rainfall amount for each reading.
3. Click "Add Reading" to append it to your session log.
4. The summary panel updates in real time showing total, average, max, and count.
5. Use the trash icon to delete any individual entry, or "Clear All" to start fresh.
6. 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