Hello all, and sorry for this stupid question. I am using my custom RSI indicator to which I created programmatically. I follow the equation type from here. My problem is when I compare it with the Trading view RSI indicator from TradingView (of course, for the same period). I have noticed many deviances sometimes. Lets take a look in an example. Let's assume in a specific time xx:xx, my custom indicator says RSI is 30.2103 and TradingView RSI says 29.8654(of course, for the same period). Why does this deviation happen? Could someone explain this to me, because I ave been struggling for so many hours to understand this problem and I would appreciate your help if you have the appropriate knowledge in this field.

  • 1
    $\begingroup$ TradingView is probably using a simple moving average of past changes while you are using an exponential moving average. Try using a SMA and see if the results match. $\endgroup$
    – Freelunch
    May 15, 2018 at 13:57

1 Answer 1


J. Welles Wilder Jr created the indicator called the Relative Strength Indicator in 1967. The indicator he originally created uses all data points in the sample series, not just the last 14 data points (or whatever period of RSI you are using).

Any data series that has less (or more) data than your current set will therefore show a different set of data. Many charting/analysis packages use a limited lookback for RSI to simplify their algorithms.

Also many data sources have longer data history than others.

Some analysis/charting software/sites simplify the RSI by replacing Welles Wilder's smoothing with their own variant. They may also restrict the historical period of calculation of the indicator, presumably for efficiency reasons.

Lastly, the historical price series in one source may have been adjusted for any of the following events: splits, reverse splits, spinoffs, corporate restructures, stock dividends, long term capital gains, short term capital gains, return of capital, special dividends, or ordinary dividends.

Unless you are able to determine the exact price adjustment methodology and RSI algorithms used, trying to figure out why one RSI is different to another is an exercise in futility.


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