The Forex Future Price Scenario Lab is an interactive Monte Carlo engine that automatically pulls real historical forex data using your Alpha Vantage API key, estimates drift and volatility from log‑returns, and generates thousands of simulated future price paths using a Geometric Brownian Motion model. Instead of claiming to predict the market, it visualizes a range of statistically plausible outcomes—complete with percentile fan charts, probability of price increase, and median projected price—giving traders a deeper understanding of uncertainty, volatility, and forward‑looking risk. It’s a lightweight, browser‑based quant tool designed for scenario analysis, education, and disciplined decision‑making.

Forex Future Price Scenario Lab

Monte Carlo GBM paths with drift/vol estimated from real historical prices via Alpha Vantage. Scenario analysis, not prediction.

Pair name (label only)

Current price

Expected drift μ (annual, %)

Volatility σ (annual, %)

Horizon (trading days)

Number of Monte Carlo paths

Alpha Vantage API Key Required

FX Pair (6 letters, e.g. EURUSD)

Fetching data…

Uses Alpha Vantage FX_DAILY endpoint (from_symbol/ to_symbol). Oldest → newest closes are used to estimate μ & σ.

Historical closing prices (one per line, oldest at top, latest at bottom)

Paste daily closes or auto-fill via API. Then you can still click “Estimate μ & σ from history” if you tweak the data.

Median price at horizon

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10th–90th percentile at horizon

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Probability price > current

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Model: Geometric Brownian Motion with constant drift and volatility estimated from log-returns of daily closes. Data source: Alpha Vantage FX_DAILY. Educational only, not trading advice or a forecasting signal. Real markets can deviate significantly from these assumptions.

How to Use the Tool

1. Enter your Alpha Vantage API key

• Paste your API key into the API Key field.

• If you don’t have one, you can get it free from Alpha Vantage.

2. Choose your forex pair

• Enter a 6‑letter pair like EURUSD, GBPJPY, AUDCAD, etc.

3. Fetch historical data automatically

• Click “Fetch Historical Data (Alpha Vantage)”

• The tool will:

  • Download daily closing prices

  • Auto‑fill the history box

  • Estimate drift (μ) and volatility (σ)

  • Update the current spot price

4. (Optional) Adjust μ or σ manually

If you want to test different market assumptions, you can override the auto‑estimated values.

5. Set your simulation parameters

• Horizon (days) — how far into the future to simulate

• Paths — number of Monte Carlo simulations (e.g., 500–2000)

6. Run the simulation

• Click “Run Price Scenarios”

• The tool will generate:

  • A fan chart showing 10th–90th percentile price paths

  • Median projected price

  • Probability the price ends higher than today

  • 10th–90th percentile range at the horizon

7. Interpret the results

• The median line shows the central tendency

• The shaded percentile bands show uncertainty

• The probability of price > current gives directional bias

• The range shows realistic volatility‑driven outcomes