Calculator Updated 2026-08-29 Runs in your browser By Ivo Renner

Position size planner

The leverage slider is the wrong place to start. Decide how much of the account you are prepared to lose on one idea, decide where the idea is wrong, and the quantity falls out of those two numbers. Leverage is then only a statement about how much margin the exchange will hold.

The arithmetic, written out

Four lines, in this order. The order matters, because it is the order in which the decisions should be made:

risk in USDT = equity × (risk% ÷ 100)
distance per unit = |entry − stop|
quantity = risk in USDT ÷ distance per unit
notional = quantity × entry
margin = notional ÷ leverage

Read the third line again, because it is the whole tool: quantity is your account risk in USDT divided by the distance from entry to stop. Leverage appears nowhere in it. A wide stop forces a small position; a tight stop permits a larger one. That is the correct relationship, and it is the reverse of how most people trade, which is to pick a leverage multiple first and then place a stop wherever it happens to leave them comfortable.

Leverage enters only on the last line, and only to tell you how much margin the exchange will lock up. It does not change the loss you take if the stop is hit — that number was fixed on line one. What leverage changes is whether the position is possible given the margin you have, and how close the liquidation price sits behind your stop.

A worked example

The defaults above: a 2,000 USDT account, 1% risk per trade, entry at 250, stop at 240, 10× leverage.

• Risk in USDT = 2,000 × 0.01 = 20 USDT.
• Distance per unit = |250 − 240| = 10 USDT.
• Quantity = 20 ÷ 10 = 2 units.
• Notional = 2 × 250 = 500 USDT.
• Margin at 10× = 500 ÷ 10 = 50 USDT.
• The stop sits 4.00% from entry.

Now change one input and watch what does and does not move. Widen the stop to 230 and the distance doubles, so the quantity halves to 1 unit and the notional falls to 250 USDT — but the 20 USDT at risk is unchanged. Change the leverage from 10× to 25× and the quantity, the notional and the risk are all unchanged; only the margin moves, from 50 USDT to 20 USDT. That is the point. The slider moved capital efficiency. It did not move risk.

Why the 5 USDT minimum notional matters here

Every TradFi perpetual launch announcement we read specifies a minimum notional of 5 USDT. On most trades that floor is irrelevant. On exactly the trades this tool is designed to encourage, it is not.

Correct sizing on a small account with a wide stop produces a small position. That is the method working as intended. But the arithmetic does not know about exchange minimums, so it will happily hand you a quantity whose notional is below 5 USDT — and that order will not fill. The calculator flags it when it happens.

When you hit the floor you have exactly three honest options. Tighten the stop, if there is a technically defensible level closer to entry — not just a closer one. Accept more risk than your rule allows, deliberately and in full knowledge that you are doing it. Or skip the trade. The dishonest fourth option, which is to size up to clear the minimum and tell yourself the stop will save you, is how small accounts die. The pre-trade checklist exists partly to catch that moment.

The tick size of 0.01 is a related nuisance: prices are quoted to two decimals, so a stop distance of a few ticks on a low-priced contract is dominated by spread and slippage rather than by your idea.

The two conditions the tool flags

The note under the readouts always states the stop distance as a percentage of entry, and adds a warning in either of two cases.

Required margin exceeds your stated account equity. This appears when the position implied by your risk rule cannot be opened with the money you have at the leverage you chose. It usually means the stop is very tight relative to the risk you are taking — a 0.2% stop with 1% account risk implies a position five times the account. The fix is a wider stop or a smaller risk percentage, not more leverage. More leverage would make the margin fit while leaving you with a liquidation price sitting almost on top of the stop.

Below the 5 USDT minimum notional. The case above: correct sizing, unfillable order.

Neither warning stops the calculation. Both are there to make you look at an input again.

What the planner deliberately leaves out

Fees are not modelled, because the rate depends on your VIP tier and on any running promotion. Your actual loss at the stop is the 20 USDT plus the round-trip fee. Slippage is not modelled either, and it is the larger of the two on a thin contract outside US hours: a stop is an order, and an order fills where the book is, not where you put it.

Funding is not modelled. A position held across settlements accrues carry that is entirely separate from the stop distance; run it through the funding cost projector for anything you intend to hold overnight.

Finally, the planner assumes the stop will be honoured at roughly the price you set. Over a weekend on a TradFi perp that assumption is weakest: the underlying does not print, the index switches mode, and the Monday re-pricing can travel straight past a stop. The gap exposure calculator and the out-of-hours guide deal with that case, and the liquidation estimator tells you how much room sits between your stop and the point of no return.