Position Sizing

When to Use

• Writing any trade plan.
• After a loss (the allowance shrinks) or a volatility regime change.

How It Works

1. Specs from the API, always. search_contracts / get_contract return
   tickSize and tickValue. The table is for sanity checks only:

   Micro	Mini	Tick size	Micro $/tick	Mini $/tick
   MNQ	NQ	0.25	0.50	5.00
   MES	ES	0.25	1.25	12.50
   MYM	YM	1.0	0.50	5.00
   M2K	RTY	0.10	0.50	5.00
   MGC	GC	0.10	1.00	10.00
   MCL	CL	0.01	1.00	10.00

   Contract ids can name a root by another symbol than the exchange's
   (the harness names contracts by their root: NQ, MNQ; another month is NQ:2026-03). Confirm with search_contracts.

2. Risk per contract = |entry − stop| ÷ tickSize × tickValue (+ round-trip
   fees from the account, if known). A stop can fill a tick or more past its
   price: when the room to the loss floor or the daily limit sets the size,
   count a tick of slippage per contract too (a policy verdict already does).

3. Risk budget = the smallest of:

   • the strategy / plan $ risk,
   • 25% of remainingBeforeLimit from get_account_snapshot,
   • 10% of the trailing-drawdown cushion (balance − loss floor).

4. Size = floor(budget ÷ risk per contract). If it's 0, the stop is too
   wide for the budget: skip, or find a tighter, structure-based stop. Never
   shrink the stop to make the size work.

5. Caps: the broker server's maxOrderSize and maxPositionSize
   (get_server_config); size 1 on micros until the setup has 30+
   reviewed trades with positive expectancy. The order gate enforces two
   of them on every entry: the size at most maxOrderSize (the harness
   records it from get_server_config, and refuses entries until it has),
   and, when the strategy sets risk.max_risk_usd, size × stop ticks ×
   tickValue at most that cap. It measures the stop from
   stopLossBracket.ticks, or from a limit or stop entry's price to the
   rationale's stop price (the farthest one on the losing side; a part tick
   counts as a whole one); a market
   entry with its stop only in the rationale can't be measured, so a
   strategy with a cap is refused unless you send stopLossBracket.ticks.
   Over a cap, reduce the size (never split the entry into several orders,
   never shrink the stop to fit). The cap is checked when the entry is
   placed: the [protect] stop you place after the fill goes where the
   rationale said, never farther.

6. A policy verdict overrides steps 3-5. While a prop attempt runs a
   policy strategy, the verdict's contract (the selected one), size, and stop
   ticks were sized from the attempt's budget (combine_status), each
   contract's risk counting its stop plus a tick of expected slippage
   (sizing.stop_slippage_ticks) and fees both ways; place at
   most that size and don't apply the 25% / 10% / size-1 caps to it. The gate
   checks the verdict, not these caps; it still refuses a size over the
   broker's maxOrderSize, and over the policy strategy's own
   risk.max_risk_usd if it sets one (its components' caps don't apply). Everything else (stop first, protective
   stop always working) still applies.

7. Half size wherever the priority order (strategy-library) halves a
   trade, computed as it says there. Never round a half up.

8. The arithmetic from order_plan. For a scan candidate (or a policy
   verdict), the harness tool order_plan does steps 2 and 4's arithmetic
   for the strategy and side you chose and shows it: the stop in points and
   whole ticks, the risk per contract, the size and where it came from (1 for
   a rules strategy, the size-1 rule; the verdict's, within the attempt's
   budget, for a policy strategy), and the dollar risk. Use its numbers
   instead of computing them by hand. The budget (step 3) and the caps are
   still your judgement: a budget below its risk is a skip, and a size you
   are allowed to raise (30+ reviewed trades) changes only size, with the
   risk scaling by it.

9. Write entry, stop, size, and $ risk into the plan.

Examples

MNQ long 21500.00, stop 21482.50 → 17.5 pts = 70 ticks × $0.50 = $35/contract
remainingBeforeLimit $600 → 25% = $150; plan risk $75; cushion $1,800 → 10% = $180
budget = $75 → size = floor(75 / 35) = 2 → capped to 1 (setup has 12 reviews)
Plan: 1 MNQ, risk $35.

order_plan for an orb long on MNQ, stop distance 5.25 pts:
stop 5.25 pts = 21 ticks ($10.50/MNQ contract), size 1, risk $10.50 = 1 x 21 ticks x $0.50/tick
(the same distance on MES: 21 ticks x $1.25 = $26.25)