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How to Trade Shares - The Relative Strength Index - RSI - Compute RSI Using Excel

Updated on June 6, 2012

The Relative Strength Index

The relative strength index (RSI) is one of the most helpful indicators that are being used by chartist in trading shares. It actually tells you when to enter and exit a position. The Relative strength index (RSI) is an oscillator that measures the velocity and magnitude of directional price movement of a stock – it compares relatively the upward and downward close to close price movements. One can say it’s a measure of the rate of rise or fall in stock price. The relative strength index was developed by J. Welles Wilder.

RSI is an oscillator that fluctuates between 0 and 100. From this a trader can define overbought and oversold levels, usually 70 and above for overbought and 30 and below for oversold.

To calculate the relative strength index, we use the two formulas below:

Calculate Relative Strength (RS) and Relative Strength Index (RSI):

1. Relative Strength (RS) = Average Upward Price Move / Average Downward Price Move

2. Relative Strength Index (RSI) = 100 - 100 / ( 1 + RS )

Compute RSI Using Excel

Before computing the relative strength index, you have to decide on the time period you want to use. Wilder used a 14 day period, but I use 8 days period to trade short cycles and 21 days period to trade the intermediate cycle.

To compute the RSI using Excel, you proceed as follow:

1. Insert the closing prices data for your stock in column “A” in Excel Spreadsheet.

2. calculate closing price change by inserting “=A1-A2” into column “B”

3. Isolate the rising prices in column “C” by inserting “=IF(B1>0,B1,0)”

4. Isolate the falling prices in column “D” by inserting “=IF(B1<0,B1,0)”

5. calculate average upward price move by inserting “=AVERAGE(C1:C8)” in column “E”

6. calculate average downward price move by inserting “=AVERAGE(D1:D8)” in column “F”

7. calculate Relative Strength (RS) by inserting =ABS(E1/F1) in column “G”

8. calculate Relative Strength Index (RSI) by inserting “=100-100/(1+G1) in column “H”

Note: If you encounter #DIV/0!, then you would have to use a longer period to avoid dividing a number by "0", otherwise you would have to introduce a negligible constant like 0.00001 to “=AVERAGE(D1:D8)+0.00001”

Hold and drag your formulas downward in as much as you would want to go into the past. Now select column H data and draw or insert a chart using Excel. You will now have an RSI oscillator as shown in the image below which you can use for entering and exiting your trades.

An RSI oscillator for entering and exiting your trades
An RSI oscillator for entering and exiting your trades

You Must Define the Trend

Important: If you use exponential moving average instead of standard moving average, then 1/8 of today’s data plus 7/8 of yesterday’s data will give you 8-day exponential moving average. If you use the formula for standard exponential moving average, then the formula will equate to 16 – day exponential moving average.

Before you attempt to trade using the RSI, you should have the following:

1. You must define the trend. Only trade using RSI in the direction of your trend.

2. Always use a Stop Loss Order which you will keep on trailing or updating as the market unfolds.

3. Buy stocks when RSI falls below the 30 level and raises back above it, but only if your trend is upward.

4. Short stocks when RSI rises above the 70 level and falls back below it, but only if your trend is downward

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    • monicamelendez profile image

      monicamelendez 5 years ago from Salt Lake City

      Awesome work in Excel!

    • chamilj profile image

      chamilj 6 years ago from Sri Lanka

      Excellent investment analysis guide. Thanks!

    • ngureco profile image

      ngureco 8 years ago

      Thank you, to you all, for your opinion and suggestions. It's important to note that if you encounter #DIV/0!, then you would have to use a longer period to avoid dividing a number by "0" (otherwise you would have to introduce a negligible constant like 0.00001 to the formula, for example “=AVERAGE(D1:D8)+0.0001”).

    • profile image

      stocktrader 8 years ago

      Great help for making the RSI in excel, I am currently developing a file where i can make a technicall analyse using excel.

      1 Note though: instead of having "A1-A2" you should make it "A2-A1" or else you will have the up and down twisted. This wil screw your RSI a bit up and in stocktrading we can not make errors right?

    • profile image

      Bigm 8 years ago

      wow, tnx. At first i was doubting your metod, but when i tried it really was usefull.

      thanks a lot

    • forlan profile image

      forlan 8 years ago

      good lesson investment hubs

    • skgrao profile image

      S K G Rao. 8 years ago from Bangalore City - INDIA.

      This is not my cup of Tea.