How do I calculate position size?

Divide the amount you are willing to lose by the distance from your entry to your stop. If you risk $100 and your stop is $5 below entry, you buy 20 units — a move to the stop costs exactly $100 regardless of the asset or its price.

What percentage of my account should I risk per trade?

Most professional traders risk between 0.5% and 2% per trade. The lower figure matters more than it sounds: at 2% risk a run of ten losses costs about 18% of the account, while at 1% the same run costs about 10%, and recovering from a smaller hole requires a much smaller gain.

Does position sizing work the same for forex and crypto?

The arithmetic is identical — risk amount divided by stop distance. What changes is the unit: shares for equities, lots for forex, coins for crypto. The calculator returns units of whatever you priced the entry and stop in.

Can position sizing make a losing strategy profitable?

No. Position sizing controls how fast you lose, not whether you lose. If your expectancy is negative, smaller size simply means a slower decline. Sizing protects a strategy that already has an edge; it cannot manufacture one.

Position size calculator

Decide how many units to buy so that hitting your stop costs a fixed, chosen percentage of your account — never more. Enter four numbers; the size falls out.

Account size

Risk per trade

Most professionals risk 0.5–2% per trade.

Entry price

Stop-loss price

Position size

20.0000

units

Position value

$2,000.00

You risk

$100.00

if the stop hits

Stop distance

5.00%

$5.00 per unit

Buying 20.0000 units at $100.00 puts $2,000.00 to work. If price reaches your stop at $95.00, you lose $100.00 — exactly 1.00% of the account, which is the point.

Position sizing is the part of risk management that actually does the work. It is what turns “this trade might go wrong” into a known, bounded number decided before you enter rather than discovered afterwards.

It cannot rescue a strategy with no edge — for that you need a positive expectancy, which you can check with the expectancy calculator. See what a given risk level does over a long run in the risk-of-ruin simulator.

Frequently asked questions

How do I calculate position size?: Divide the amount you are willing to lose by the distance from your entry to your stop. If you risk $100 and your stop is $5 below entry, you buy 20 units — a move to the stop costs exactly $100 regardless of the asset or its price.
What percentage of my account should I risk per trade?: Most professional traders risk between 0.5% and 2% per trade. The lower figure matters more than it sounds: at 2% risk a run of ten losses costs about 18% of the account, while at 1% the same run costs about 10%, and recovering from a smaller hole requires a much smaller gain.
Does position sizing work the same for forex and crypto?: The arithmetic is identical — risk amount divided by stop distance. What changes is the unit: shares for equities, lots for forex, coins for crypto. The calculator returns units of whatever you priced the entry and stop in.
Can position sizing make a losing strategy profitable?: No. Position sizing controls how fast you lose, not whether you lose. If your expectancy is negative, smaller size simply means a slower decline. Sizing protects a strategy that already has an edge; it cannot manufacture one.

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These calculators are educational and are not financial advice. They describe arithmetic, not outcomes — no position size makes a losing strategy profitable. Trading carries risk, including loss of capital.