RavingDesk Position Size & Risk Planner

What it is for

Most beginners choose a position size first and think about the stop later. This planner turns that around: you decide how much of the account you are willing to lose if the trade goes wrong, where your stop goes, and the planner tells you how many units fit that budget.

You enter the direction (long or short), account size, risk per trade in percent, entry, stop and target prices, and an estimated round-trip fee. The result is the number of units, the loss at the stop, the profit at the target, the reward/risk ratio, the position value and a small table of what happens if the price moves 5 or 10 % either way.

It is the risk planner of the RavingDesk paper-trading workspace. It never places an order, fetches no prices, and it is not investment advice.

Worked example

You practise with a 20,000 paper account and accept a 1.5 % risk. You plan a long at 42 with a stop at 39.5 and a target at 48, and expect about 6 in fees for buying and selling.

The risk budget is 1.5 % of 20,000 = 300. The fee is taken out first, leaving 294, and each unit loses 2.50 between 42 and 39.5, so 294 ÷ 2.5 = 117.6 units. At 48 each unit gains 6: 705.60 minus the fee is 699.60, a little more than twice the risk.

The move map shows the planned 117.6 units at 37.8 (−10 %) losing 493.92 before fees — far more than 300, because it assumes the stop did not save you.

How to read the result

• Units is the most important number. It is fractional; round it down to whole shares, coins or lot sizes yourself.
• Loss at stop always equals the risk budget, because the size was calculated from it.
• Reward / risk below 1 triggers a warning: the target pays less than the stop costs.
• Position value is units × entry. If it is larger than the account, a warning says that holding it would need leverage or margin, which the planner does not model.

Tips and common mistakes

• Put the stop where the trade idea is wrong, then size — never move the stop to fit a size you wanted anyway.
• A tight stop makes the position huge. The example with entry 20 and stop 19.8 on a 5,000 account gives 495 units worth 198 % of the account.
• For a short, the stop is above the entry and the target below; the planner refuses the wrong order with Place the stop and target on the correct sides of entry.
• Include both fees. If the fee is as large as the risk budget, there is no room for a position at all.
• Stops are not guaranteed fills. Gaps and slippage can make the real loss larger than planned.

FAQ

Does this work for short positions?

Yes. Choose Short: the planner uses the distance from entry up to the stop and flips the signs in the move map.

Why is the profit at target not exactly reward/risk times the risk?

Because the fee is subtracted on both sides of the calculation: it reduces the size and also the profit.

Can I send the result to an order?

In the RavingDesk workspace, Use in order ticket pre-fills a paper limit order with the side, quantity and entry. It is still a paper order you record yourself.

Does it consider margin, financing or taxes?

No. It assumes fills exactly at entry, stop and target, in one account currency, without borrowing costs or taxes.