---
title: "Curve Number Calculator"
canonical: "https://help.innovyze.com/space/infodrainage2021v1/16547904/Curve%20Number%20Calculator"
format: markdown
---
The Curve Number Calculator allows the curve number to be calculated for the SCS runoff method.

![image](media://f2ae0216-1561-4a68-8583-19a373b9ba42)

As different options are selected from the drop-down list, the appropriate curve number is selected. Clicking OK will select the currently displayed curve number.

Curve Numbers are calculated by looking up the values in the tables 2-2a to 2-2d in document  , authored by [Natural Resources Conservation Service (NRCS)](http://www.nrcs.usda.gov/). TR-55 is a widely used approach to hydrology in the US.