Fixed size

Fixed sizing uses the same number of contracts / units on every trade regardless of capital, volatility, or risk.

Shape

"position_sizing": {
  "method": "fixed",
  "fixed_size": 0.1
}

OR (fallback if fixed size isn't valid for the venue):

"position_sizing": {
  "method": "fixed",
  "fixed_pct": 10
}

Params

• fixed size - constant unit count (e.g. 0.1 BTC).
• fixed percent - fallback fixed percent of capital.

When to pick this

• Testing: the simplest sizing for early-stage backtests.
• Validating exchange order plumbing without varying risk.
• Per-unit strategies where every entry is the same fixed size.

Pitfalls

• No risk control. A bad backtest run with fixed size will eat the full balance.
• Doesn't scale with capital. A profitable strategy will produce the same dollar P&L per trade regardless of account size.