How to calculate position size in Sierra Chart

Contracts = risk in dollars ÷ (stop distance in ticks × currency value per tick). On ES at $12.50 a tick, a 12-tick stop and $300 of risk gives 2 contracts. On MES at $1.25 a tick, the same trade gives 20. Everything below is that one line, unpacked.

The formula

contracts = risk $ / (stop ticks x currency value per tick)

Three inputs, and only one of them is a decision:

• Risk in dollars — what you are willing to lose on this trade. Your choice, made before you look at the chart. If you work in percentages, it is your account balance times the percentage.
• Stop distance in ticks — where the trade is wrong, measured from the entry. The chart decides this, not you.
• Currency value per tick — what one tick is worth on the instrument you are trading. The contract decides this.

Where the two chart values come from

Sierra Chart already knows both. Open Chart >> Chart Settings >> Symbol and you will find Tick Size and Currency Value Per Tick. Tick size converts a price distance into ticks; the tick value converts ticks into money.

For reference, the common CME contracts. Your chart is the authority — check it rather than trusting a table:

Worked example: ES

You are willing to risk $300. Entry at 5642.00, stop at 5639.00. That is 3.00 index points, and at a tick size of 0.25 it is 12 ticks.

stop in money  = 12 ticks x $12.50 = $150 per contract
contracts      = $300 / $150       = 2 contracts
actual risk    = 2 x $150          = $300

Worked example: MES

Same trade, same stop, on the micro instead. Only the tick value changes:

stop in money  = 12 ticks x $1.25  = $15 per contract
contracts      = $300 / $15        = 20 contracts
actual risk    = 20 x $15          = $300

Same dollar risk, same stop, two very different position sizes. That is the whole point of sizing from risk rather than picking a number: the quantity is an output.

The mistake that costs the most

A chart whose Currency Value Per Tick belongs to the full-size contract while you trade the micro. It happens when a chart is set up for ES and later pointed at MES, and nothing warns you. Every dollar figure then reads ten times too big on the S&P contracts, and sizing from it puts on a tenth of the position you intended — or, the other way round, ten times too much.

Before you trust any number, sanity-check one tick against what you know the contract is worth. It takes five seconds and it is the single most common way this arithmetic goes wrong.

Always round down

Real answers are rarely whole. $300 of risk with a 17-tick stop on ES gives 300 / (17 x 12.50) = 1.41 contracts. Take 1, not 2. Rounding up overshoots your risk budget by 41% on that trade, and doing it repeatedly is how a plan that looks conservative on paper stops being conservative.

If rounding down leaves you at zero, the stop is too wide for the account, not the other way round. That is useful information, and it is the answer the arithmetic is giving you.

Why it is harder in practice

None of the above is difficult. Doing it in the eight seconds before a level is gone, correctly, repeatedly, with the stop moving as you look for the right wick to hide behind, is the hard part. Recalculating by hand every time you nudge the stop is what people stop doing first, and it is exactly the moment the sizing matters.

Doing it on the chart instead

That is what this site sells. Position Size Calculator Pro does this arithmetic continuously while you move the stop: you give it the dollar amount you are willing to risk, and it works out the contract count and draws entry, stop and targets anchored to the candle, with the dollar risk and the reward-to-risk on the labels. It reads the same two chart values described above, and it never places, modifies or cancels an order.

$19.99 for Standard, $29.99 for Pro, one-time. The setup guide and the known limits are public before you buy. And if you came here for the formula, you already have it — it is the same one.

Related: Does Sierra Chart have a position size calculator?