How to use it
- Type your Account size and the share you are willing to lose in Risk per trade.
- Enter the Entry price and the Stop-loss price. The stop can be below the entry for a long position or above it for a short one.
- Choose Whole units only for shares, or Fractions allowed for units that can be split.
- Read Units to buy and Loss if the stop is hit, then open How the units are worked out to check each step.
How the units are calculated
The money at risk is the account multiplied by the risk per trade. The distance is the gap between the entry price and the stop-loss price, and it counts the same above or below the entry. Dividing the money at risk by the distance gives the number of units, so that a move from the entry to the stop loses the money at risk.
money at risk = account × risk per trade ÷ 100
distance = |entry price − stop-loss price|
units = money at risk ÷ distance
loss if the stop is hit = units × distance
position value = units × entry price- Whole units are rounded down, so the loss is never more than the money at risk.
- A wider stop means fewer units for the same money at risk.
What a stop-loss order is
A stop order, also called a stop-loss order, is an order to buy or sell a security once its price reaches a set level, the stop price. When the stop price is reached, the order becomes a market order. According to the U.S. Securities and Exchange Commission, a sell stop is entered below the current price and a buy stop above it.
What this calculator does not include
- Advice on what to buy or sell, or when. The calculator sizes a position you have already chosen.
- Fees, commissions, taxes and financing costs.
- Any fill other than the stop price: the result assumes the exit happens exactly at the stop.
Worked example: 10,000 account, 1% risk, entry 50, stop 48
The money at risk is 1% of 10,000, which is 100. The distance from the entry price of 50 to the stop price of 48 is 2. Dividing 100 by 2 gives 50 units. If the stop is hit, the loss is 50 × 2 = 100, and the position is worth 50 × 50 = 2,500 at entry.
| Step | Result |
|---|---|
| Money at risk (1% of 10,000) | 100.00 |
| Distance from entry to stop | 2.00 |
| Units (100 ÷ 2) | 50 |
| Loss if the stop is hit (50 × 2) | 100.00 |
| Position value (50 × 50) | 2,500.00 |
Frequently asked questions
What is position size?
It is the number of units you buy so that a loss at your stop-loss price costs a share of your account that you chose in advance. The share is your risk per trade, and it is your decision.
Why does the distance to the stop decide the units?
The loss depends on how far the price moves between your entry and your stop. For the same money at risk, a wider stop means fewer units, and a closer stop means more.
Does a stop-loss order guarantee the price I set?
A stop order becomes a market order once the stop price is reached, so this page does not promise the price you will get. The calculator assumes the exit happens at the stop price.
Is this trading or investment advice?
No. It does the arithmetic of a risk plan. It does not say what to buy, when to buy it or at what price. Speak to a qualified adviser before you invest.
Does the calculator keep what I type?
No. The numbers are worked out in your browser. Nothing you enter is sent to us or stored.
Sources
Figures and text last checked on Thursday, November 12, 2026.