Find the exact number of shares, units or lots to trade so you never risk more than you planned. Free, instant, and works for forex, stocks and crypto.
Needs $2,000.00 in buying power — about 20% of your $10,000.00 account. No leverage required.
Your stop-loss is 1R — the risk you set. Each target pays a multiple of that risk if price reaches it before your stop.
| Target | Price | Profit |
|---|---|---|
| 1R | 105.00 | +$100.00 |
| 2R | 110.00 | +$200.00 |
| 3R | 115.00 | +$300.00 |
Mantis automatically calculates your position sizes and tracks your R-multiple on every trade — no spreadsheet, no manual maths.
Download on theApp StoreFree to start · iOS 18+ · No account required
Pick how much of your account you are willing to lose on this one trade — usually 0.5% to 2%. On a $10,000 account, risking 1% means you accept a $100 loss if the trade goes against you. This is the single most important number in trading: it caps your downside before you even enter.
Your per-unit risk is the distance from your entry price to your stop-loss. Buy a stock at $100 with a stop at $95 and you are risking $5 per share. The wider your stop, the fewer units you can hold for the same dollar risk — tight stops allow larger positions, wide stops force smaller ones.
Divide your dollar risk by the per-unit risk: $100 ÷ $5 = 20 shares. That is the largest position you can take while keeping your loss at your stop to exactly $100. The same formula works for forex units and crypto coins — only the units change, never the maths.
Once a trade is sized, its risk becomes "1R". A target at 2R aims to make twice what you risked; a full stop loses 1R. Logging every trade in R lets you judge your edge across different account sizes and instruments without dollar amounts muddying the picture.
Position size is your dollar risk divided by your risk per unit. First find the dollar risk: account size multiplied by your risk percentage (e.g. $10,000 × 1% = $100). Then find the per-unit risk: the distance between your entry price and stop-loss (e.g. $100 entry − $95 stop = $5). Divide the two: $100 ÷ $5 = 20 shares. This sizes the trade so hitting your stop loses exactly the amount you chose to risk.
Most professional traders risk between 0.5% and 2% of their account on any single trade. Risking 1% means a 10-trade losing streak only draws your account down by roughly 10%, leaving plenty of capital to recover. Higher percentages grow accounts faster but make a string of losses far harder to come back from.
Yes. The underlying maths is identical for all three: dollar risk divided by the price distance to your stop. For stocks the result is shares, for crypto it is coins or tokens, and for forex it is units, which the calculator also converts to standard lots (1 lot = 100,000 units), assuming the pair's quote currency matches your account currency.
An R-multiple expresses profit or loss as a multiple of the amount you risked. Your initial risk is 1R. If you risk $100 and make $200, that trade is +2R; if you lose your full stop, it is −1R. Sizing every trade to risk the same R lets you compare trades of different sizes on one common scale.
Yes, this calculator is completely free, runs entirely in your browser, and requires no sign-up. Nothing you type is sent to a server. Mantis, our iOS trading journal, does the same position-size and R-multiple maths automatically on every trade you log.
Important: Mantis is a trading journal and analytics tool. This calculator is for educational purposes and is not investment advice, not financial advice, and not a recommendation to buy or sell any security or instrument. Trading involves risk; past performance does not guarantee future results. Consult a qualified professional before making financial decisions.