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Size a spot position
The number of coins is the last answer, not the first decision. Start with your planned risk and the exit distance.
Connect quantity to a chosen hypothetical loss budget.
Position size is the amount of an asset held. A stop level alone does not describe account risk: the same price movement has different cash effects on one unit and one hundred units. Choose a practice loss budget before calculating quantity.
For a simple unleveraged long, estimated quantity equals the cash risk budget divided by entry price minus planned stop execution price. This assumes the stop fills as modeled. Include a sensible cost allowance, respect minimum order increments and check that purchase cost fits available cash.
A tighter stop permits a larger computed quantity but may be triggered by ordinary movement. It does not create a safer idea. If fees or a realistic adverse fill consume the budget, reducing quantity or skipping the hypothetical trade is a valid result.
Let’s use numbers · hypothetical example
Hypothetical: budget 20 quote units, entry 100, stop 96. Ignoring costs, 20/4 = 5 units, costing 500. Reserving 4 for costs leaves 16/4 = 4 units. Gaps can still exceed the estimate.
Keep in mind
The chosen budget is an illustration, not a recommended percentage or guaranteed maximum loss.
Your turn
Recalculate with entry 100 and stop 92. Compare quantity while keeping the same cash budget.
A quick check before we move on
What happens to quantity when stop distance doubles?
- It is unchanged
- It halves under the same simplified budget
- It doubles
Check answer
It halves under the same simplified budget Quantity is inversely related to the modeled loss per unit.
Sources and further reading
Content reviewed: 29 October 2026
Educational material with hypothetical examples. Trading can cause substantial losses. A course, pattern, stop order or past result cannot guarantee a profit or limit every loss. Practise in simulation and check current rules and product terms in your jurisdiction.