You can download the following excel sheet, to take a look at how RSI is calculated.

RSI calculation uses close price of a stock.

“Column E” has all closing prices.

“Column F” calculates change in price by subtracting current row from previous row.

If “Column F” value is greater than zero, value will be copied to Column G. If value is less than zero, value will be copied to “Column H”.

“Column I” calculates the average Gain over the specified period, example 14.

“Column J” calculates the average Losses over the specified period, example 14.

“Column K” calculates the value of Relative Strength (RS).

“Column L” calculates the value of Relative Strength Index(RSI).

You can download the excel file from the following link.

RSI calculation