Position Size Calculator for Crypto Futures

key_takeaways

Key takeaways

• Your size comes from the loss you accept and the distance to your stop.
• Leverage changes the margin a position locks, not the size and not the loss at the stop.
• A fee per side makes the size smaller, so the loss at the stop still matches your risk.

How to use the position size calculator

• Enter your account balance in USD.
• Pick how you define risk: a percentage of the balance or a fixed USD amount, then enter it.
• Enter your entry price and your stop-loss price. A stop below the entry is read as a long, a stop above it as a short.
• Optional: add the fee per side as a percentage and your leverage. The fee makes the size smaller so the loss at the stop still matches your risk. Leverage only adds the margin figure.
• Read the size in coins. Round it down to the step your venue allows.

The calculator opens with the hypothetical values of the worked example on this page, marked as example values. Replace them with your own, or press Clear to empty every field. The fee and the leverage in the example are invented. The tool does not know your venue, so enter your venue’s fee and your own leverage.

Position size formula

The size comes from the loss you accept divided by the loss per coin at your stop. With fees, each coin also costs the entry fee and the exit fee.

risk USD   = balance x risk%        (or your fixed USD amount)
stop dist  = |entry - stop|
fee / coin = fee% x (entry + stop)  (0 if the fee field is empty)
size       = risk USD / (stop dist + fee / coin)
notional   = size x entry
margin     = notional / leverage
stop %     = stop dist / entry x 100
loss@stop  = size x (stop dist + fee / coin)   = risk USD

Worked example

What is position sizing?

Position sizing is the decision of how many coins to trade. The method here starts with the loss you accept, not with the margin you have. You choose the amount you can lose on one trade, you place the stop where the trade idea is wrong, and the size follows from those two choices.

One method defines risk as a fixed fraction of the balance, so the dollar loss shrinks after losses and grows after wins. Another uses a fixed USD amount. Both are ways to keep one stop-out small compared with the account. Which value fits is a decision for your own plan.

Why does the stop distance change your size?

The loss at your stop equals size times stop distance. If the loss is fixed, a wider stop means fewer coins and a tighter stop means more coins. Two trades with the same risk amount can have very different sizes and notional values. Place the stop first, based on the chart, then let the calculator work out the size. Doing it the other way round bends the stop to fit the size you wanted. For more on stop placement, read the stop-loss basics.

Position size is not trade value

Notional is size times price. It is the exposure, and it can be many times your balance. Risk is what you lose if the stop is hit. A large notional with a very tight stop can carry the same risk as a small notional with a wide stop. Judge a trade by its risk amount and its stop distance, not by how large the position looks.

Crypto and futures notes

• Coins and contracts. The calculator gives coins of the base asset. On linear contracts, one contract usually stands for a fixed amount of the base coin. Divide by your contract size and round down to the allowed step.
• Leverage. Leverage changes the margin that gets locked. It does not change the size, and it does not change the loss at your stop.
• Capacity. If the margin needed is higher than your balance, the position cannot be opened as sized. The result panel warns you and shows the largest size your balance and leverage allow.
• Perpetuals run all day. Funding payments and price gaps can move your loss away from the planned figure. See the leverage and margin basics.

Common mistakes

• Sizing from leverage. Maximum leverage says what you may open, not what you should risk.
• Ignoring fees. On tight stops, entry and exit fees can be a visible share of the risk. See maker vs taker fees (also: slippage can widen the real loss).
• Moving the stop after sizing. A new stop needs a new size.
• Risking the same amount on every idea. Several open trades add up. Check the total, not just one line.

Limits of this calculator

It assumes a linear contract where profit and loss equal size times price change. It does not include slippage, funding, partial fills, margin tiers, rounding to lot size, or a liquidation price. A stop order that fills beyond your stop price loses more than the figure shown. Your venue’s exact rules, fees and margin tiers decide what you can open. Results are estimates.

Position size calculator FAQ

How much should I risk per trade?

There is no single right number, and this tool does not give one. One method defines risk as a fixed fraction of the balance, so that one loss stays small compared with the account. Another uses a fixed USD amount. Choose a value that fits your own plan and, in a challenge, your own rulebook limits.

Does leverage change my position size?

No. Size comes from your risk amount and your stop distance. Leverage changes how much margin is locked to open that size. Higher leverage means less margin per trade, but the same price move still costs the same dollars.

How do fees change the result?

A stop-out costs the price loss plus the entry fee and the exit fee. When you enter a fee per side, the calculator reduces the size so the total loss at the stop, fees included, matches your risk amount. Leave the field empty to ignore fees.

What is the difference between contracts and coins?

On linear contracts, one contract is usually a fixed amount of the base coin. This calculator shows coins. Divide by your venue’s contract size to get contracts, and round down to the step it allows.

How does the calculator know if my trade is long or short?

It reads it from your prices. A stop below the entry means a long, a stop above the entry means a short. If the stop equals the entry, the tool asks for a different stop, because the loss per coin would be zero.

Is this also a stop-loss calculator?

Yes, in the sense that it works backward from the stop. You give it the stop and the risk, and it returns the size. It does not suggest where to put the stop. That is a chart decision.

Can I use this when I trade a challenge?

As a planning aid, yes. Enter the balance and size each trade so the loss at the stop fits inside the limits of your own rulebook. The calculator does not know any firm’s rules and does not track daily or trailing drawdown. For the concepts, read what a drawdown is.