Speedy Calculator

Relative Strength Index Calculator (RSI)

Finance Updated October 25, 2026

Quick answer

The RSI calculator works out the relative strength index of a list of closing prices using Wilder's smoothing – for any period (14 by default) – and whether the asset looks overbought or oversold, along with simple, exponential and weighted moving averages.

Relative strength index (RSI)
—
Signal
—
Simple moving average
—
Exponential moving average
—
Weighted moving average
—
SMA series (period: value)
—

J. Welles Wilder introduced the RSI in 1978. Readings above 70 are traditionally read as overbought and below 30 as oversold; in strong trends RSI can stay extreme for a long time. Everything is calculated in your browser, so nothing you type is sent to our server.

How to use the Relative Strength Index Calculator

  1. Closing prices (oldest first)
  2. RSI period
  3. Moving-average length

Everything runs in your browser, so results appear instantly and nothing you type is sent to a server.

How it works

Paste closing prices in date order (oldest first) and choose the RSI period and moving-average length.

Tips

  • Enter figures for the same period and in the same currency.
  • Exchange rates and prices change constantly – update them before you rely on a result.
  • Use results as estimates and confirm important figures with the official source.
  • Everything runs in your browser – try different values to compare scenarios.

Common mistakes to avoid

  • Mixing gross and net figures.
  • Using outdated rates.
  • Treating rules of thumb as exact.

Formula

Average gain and loss over the first n periods, then smoothed: avg = (previous avg × (n − 1) + current) ÷ nRS = average gain ÷ average lossRSI = 100 − 100 ÷ (1 + RS)

Worked example

Inputs — Closing prices (oldest first): 44.34, 44.09, 44.15, 43.61, 44.33, 44.83, 45.10, 45.42, 45.84, 46.08, 45.89, 46.03, 45.61, 46.28, 46.28, 46.00, 46.03, 46.41, 46.22, 45.64; RSI period: 14; Moving-average length: 10.
Results — Relative strength index (RSI) = 57.92; Signal = Neutral; Simple moving average = 46.039; Exponential moving average = 45.8704; Weighted moving average = 46.0576; SMA series (period: value) = 10: 44.779
11: 44.934
12: 45.128
13: 45.274
14: 45.541
15: 45.736
16: 45.853
17: 45.946
18: 46.045
19: 46.083
20: 46.039.

Frequently asked questions

What is the RSI?

A momentum oscillator from 0 to 100 measuring the speed of price changes.

What RSI period should I use?

14 is standard; shorter periods are more sensitive.

What does RSI above 70 mean?

The asset may be overbought.

What formula does the Relative Strength Index Calculator use?

Average gain and loss over the first n periods, then smoothed: avg = (previous avg × (n − 1) + current) ÷ n.

Cite this calculator

Speedy Calculator. (2026). Relative Strength Index Calculator (RSI). Speedy Calculator. https://speedycalculator.com/calculators/finance/relative-strength-index/