Free trading & investing calculators
Single-purpose calculators with the same formulas Drogo uses internally — no sign-up, no ads, just the math. Each tool ships with its formula and a pro-grade FAQ.
Trading
- RSI calculator (Wilder, 14-period)
Free RSI calculator. Paste 15+ closing prices and compute the Wilder Relative Strength Index used by professional traders.
- ATR calculator (Average True Range)
Free Average True Range calculator. Paste OHLC bars and get Wilder's 14-period ATR used for stop-loss sizing.
Risk
- Position size calculator (fixed-risk)
Free position size calculator using a fixed percent of account equity. Outputs share count, dollar risk and notional exposure.
- Stop-loss calculator (ATR and percent modes)
Free stop-loss calculator with ATR-multiple and fixed-percent modes. Returns stop distance, breakeven and reward-to-risk targets.
- Drawdown calculator (max DD and recovery)
Free drawdown calculator. Paste an equity curve and compute max drawdown, current drawdown and the gain required to recover.
- Kelly criterion calculator (full and fractional)
Free Kelly criterion position-sizing calculator. Compute optimal bet fraction from win rate and average win/loss.
Investing
- Compound interest calculator (with contributions)
Free compound interest calculator. Project portfolio growth with monthly contributions, annual return and any time horizon.
- Sharpe ratio calculator (annualised)
Free Sharpe ratio calculator. Paste a return series and get the annualised excess-return-per-unit-volatility figure used in finance.
- Dividend yield calculator (forward and TTM)
Free dividend yield calculator. Compute yield on cost, current yield, and the price needed for a target yield.
Options
- Options P&L calculator (vertical and single-leg)
Free options profit and loss calculator. Compute payoff at expiration for calls, puts and vertical spreads.