Size from your daily loss limit.

What it reads

Four numbers you type: the daily loss limit your program sets (or your own, if it is lower), how many attempts you will allow yourself today, the stop distance in the market’s price units, and your costs per unit. The market sets what a 1.00 move is worth per unit: $5 a point on MES, $50 on ES, $1 per share or per coin, or a value you enter.

How it is computed

Risk per attempt = daily loss limit ÷ attempts

size = floor( risk per attempt ÷ ( stop distance × dollars per 1.00 move + costs per unit ) )

limit left after k full losses = daily loss limit − k × size × risk per unit

Worked example, MES: a $1,000.00 daily loss limit and 4 attempts give $250.00 per attempt. A 10-point stop is 10 × $5 = $50, plus $1.50 of costs = $51.50 per contract. $250.00 ÷ $51.50 = 4.85, which rounds down to 4 contracts and $206.00 at risk per attempt. After one full loss, $794.00 and 3 attempts are left. After all 4, $176.00 of the limit was never risked.

Why that matters

A daily loss limit is a fixed amount for the whole day, and the day usually has more than one trade in it. Deciding the number of attempts first turns the limit into a size you can keep: the size does not depend on how the last trade went, so a loss costs one attempt and never two.

What it does not tell you

Whether the stop is in the right place, whether any attempt is worth taking, or how your trades will go. It always rounds down, so it never plans more than the limit. A stop can still gap or slip past its price, so a realised loss can be larger than the planned one. Programs differ on whether open losses count toward the daily limit and on what happens when it is reached: read your program’s own rules. This is arithmetic, not advice.

How many contracts can I trade with a daily loss limit?

Divide the daily loss limit by the number of attempts you allow yourself, then size each attempt to its stop: size = floor(risk per attempt ÷ (stop distance × dollars per 1.00 move + costs)). With a $1,000.00 limit, 4 attempts and a 10-point MES stop with $1.50 of costs, that is 4 contracts risking $206.00 per attempt.

Why size from the daily limit and not from the last trade?

The limit is what the day can lose, and it does not reset after a loss. Sizing up after a loss spends more of what is left on one attempt: in the example, a doubled second attempt that is stopped leaves room for 1 more attempt at the planned size instead of 2.

Does the calculator include slippage?

Costs per unit are counted as risk, so commission and expected slippage belong in that box. A stop can still gap or slip past its price, so a realised loss can be larger than the planned one. If your program closes the account at the limit itself, enter a lower limit as your own buffer.