Perp Position Size Calculator

A standalone trading calculator for perpetual futures platforms like Lighter, Hyperliquid, and Tradovate. Enter portfolio size, risk amount, entry price, stop loss, and take profit — the tool instantly calculates position size, margin needed, max loss, R:R ratio, and potential profit. Includes a leverage slider, long/short toggle, and warnings when margin exceeds portfolio. Runs locally in any browser with no internet connection required. Built with Claude in a single session.