# RSI Formula

## Relative Strength Index (RSI) Formula

The **RSI formula** is relatively simple. You just need to understand the concept of **Relative Strength** and understand how to sum up and average up and down moves of the market for which you want to calculate RSI.

### RSI formula

**RSI = 100 – 100 / ( 1 + RS )**

RS = Relative Strength = U / D

U = average of all positive moves in the last N price bars

D = average of (absolute values of) all negative moves in the last N price bars

N = the period of RSI

## How to Calculate RSI

A detailed step by step guide **how to calculate RSI**, with a detailed **decomposition of the RSI formula**, is here: RSI Calculation.

## RSI Values

RSI can reach values from 0 to 100. It is quite obvious from the RSI formula. You use absolute values for average negative move calculation, therefore Relative Strength is always positive, the denominator at the end of the RSI formula ( 1 + RS ) is always greater than 1, and the result of RSI formula is never negative and never greater than 100.