Relative Strength Index Calculator (RSI)

Written by Great Medico

Updated September 25, 2026 •2 min read

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The fastest way to make a finance estimate useful is to know exactly what went into it. Relative Strength Index Calculator (RSI) puts the relevant inputs beside the result so you can test the calculation instead of treating the number as a black box. On this page, it calculates a Relative Strength Index from the displayed chronological price series.

What this calculator does

Relative Strength Index Calculator (RSI) calculates a Relative Strength Index from the displayed chronological price series. Its visible inputs are Period, Price 1, Price 2, Price 3, Price 4, Price 5, Price 6, Price 7, Price 8, Price 9, Price 10, Price 11, Price 12, Price 13, Price 14, Price 15, Price 16. The article follows those fields and the calculation that is actually available on this page; it does not silently add live market feeds, tax tables, legal eligibility tests, or other variables that are not present in the tool.

How to use it

Enter Period, Price 1, Price 2, Price 3, Price 4, Price 5, and the remaining displayed fields. Use the units and percentage scale shown beside each field, and keep values on the same time basis when the formula compares income, rates, prices, balances, or work hours.

How the calculation works

The page calculates gains and losses over the selected period, finds average gain and average loss, forms RS = average gain ÷ average loss, and returns RSI = 100 − 100 ÷ (1 + RS).

Example

Using the page’s demonstration values (Period = 14; Price 1 = 44.35; Price 2 = 44.7; Price 3 = 45.05) and leaving the remaining defaults unchanged, the calculator returns 100 for relative strength index (rsi). Replace the sample inputs with values from the same period and definition before interpreting your own result.

How to interpret the result

Interpret the output according to the metric being calculated: a ratio, score, exchange relationship, chart level, safety incidence rate, or cost comparison. It is best for consistent measurement and scenario comparison, not for turning one metric into a complete business or investment decision. Traditional charting convention often calls RSI at or above 70 overbought and at or below 30 oversold, but those labels are descriptive rather than predictive.

Limitations and notes

The page uses the displayed chronological price series and selected period. Traditional 70/30 labels are descriptive trading conventions, not buy/sell instructions. RSI can remain high or low for extended periods in strong trends. The result should not be treated as a standalone trading signal. This tool uses the data you enter and does not independently validate the underlying source, legal classification, market quote, accounting treatment, or workplace recordability decision. A clean calculation can still be wrong if the source data or definition is wrong.