Index Position Size Calculator for [US30 / US100 / SP500]

What it does
This tool helps you size positions consistently for index trades on US30 (Dow Jones), NAS100 (Nasdaq-100), and SP500 (S&P 500). Enter your account balance, risk %, and your planned Entry / Stop-Loss / Target and the script calculates:
• Position Size (rounded to your lot/contract step)
• Risk-to-Reward (R/R)
• Potential P/L in USD based on your inputs
• Visual Entry / SL / TP lines with green/red zones and concise labels

Supported contract styles
Choose a preset for common products (e.g., CFD $1/pt, YM/NQ/ES futures, MYM/MNQ/MES micros) or override the economics yourself. You remain in control of the two key levers:
• $/point — how many dollars you gain/lose per 1 index point per contract/lot
• Point size — how many price units equal 1 index point on your chart (often 1.0, but some brokers use 0.1 or 0.5)

Inputs
• Account Balance ($) and Risk % per trade
• Index: US30 / NAS100 / SP500
• Contract: CFD / Futures (YM, NQ, ES) / Micros (MYM, MNQ, MES)
• $/point: auto from Contract or manual override
• Point size: auto from Index or manual override
• Position size step: rounding (e.g., 1 for futures, 0.01 for CFDs)
• Entry / SL / TP: typed values (snapped to tick), with on-chart zones and labels
• Display toggles for lines and labels

How the math works
• StopPoints = |Entry − SL| ÷ PointSize
• ProfitPoints = |TP − Entry| ÷ PointSize
• Position Size = (AccountBalance × Risk%) ÷ (StopPoints × $/point)
• R/R = ProfitPoints ÷ StopPoints
• Potential P/L = PositionSize × Points × $/point

How to use (quick start)
1. Select Index and Contract.
2. Confirm $/point and Point size match your broker’s specs.
3. Enter Entry / SL / TP for the trade idea.
4. Read the Position Size, R/R, and Potential P/L in the info box.
5. Adjust for fees, spreads, and slippage as needed.

Notes & limitations
• Broker symbols can vary. Always verify $/point and Point size for your instrument before risking capital.
• The script does not place orders and does not generate trade signals; it’s a sizing/visualization tool.
• Results can differ across brokers due to pricing, spreads, minimum lot sizes, and execution rules.
• Use on the intended indices; you’ll see a reminder if you load it elsewhere.

Changelog highlights
• Pine v6, constant-safe inputs, tick-snapping, global fills (no local-scope errors).
• Robust label handling and optional minimal chart markers.

Disclaimer
This script is provided for educational purposes only and does not constitute financial advice or a recommendation to buy or sell any security or derivative. Trading involves risk, including the possible loss of principal. Always do your own research, verify contract specifications with your broker, and consider testing in a demo environment before trading live.