How to Use Relative Strength Index Calculator
The Relative Strength Index Calculator turns a list of closing prices into a single RSI reading. Paste prices, choose a period, and the Relative Strength Index Calculator returns the current RSI and zone.
- Set Period — Most traders use 14, but 7 or 21 are common too.
- Paste Closing Prices — Comma, space, or new-line separated.
- Read RSI — Compare to 30 / 70 thresholds.
Formula & Theory - Relative Strength Index Calculator
The Relative Strength Index Calculator uses Wilder’s smoothing:
Step 1: For first N periods, compute average gain and average loss.
AvgGain = Σ gains / N
AvgLoss = Σ losses / N
Step 2: For subsequent periods, smooth:
AvgGain = (Prev AvgGain × (N − 1) + Current Gain) / N
AvgLoss = (Prev AvgLoss × (N − 1) + Current Loss) / N
Step 3: RS = AvgGain / AvgLoss
RSI = 100 − 100 / (1 + RS)| Symbol | Meaning |
|---|---|
| Gain | max(close − prev close, 0) |
| Loss | max(prev close − close, 0) |
| N | Period length |
Assumptions and Limits
The Relative Strength Index Calculator assumes regular interval closing prices. It does not handle splits or dividends automatically. Use adjusted closes for equities.
Use Cases for Relative Strength Index Calculator
The Relative Strength Index Calculator is helpful for:
- Momentum check — Spot overbought or oversold conditions.
- Divergence analysis — Compare RSI direction to price direction.
- Multi-timeframe — Run on daily and weekly closes for confirmation.
- Backtesting prep — Compute RSI for historical windows quickly.
Run the Relative Strength Index Calculator on different periods to find what best fits your strategy.