What you will learn
- 1Know your account balance and risk %
- 2Convert risk % into money
- 3Set your stop-loss in pips
- 4Find the pip value for the pair
- 5Apply the position-size formula
- 6Round down to a safe lot size
- 7Verify with a position-size calculator
- 8Re-check when balance or volatility changes
Estimated reading time: 12 minutes
Position size is the amount of an instrument you trade — expressed in lots — and it is the most important risk decision you make on every single trade. Get it right and a losing streak is survivable; get it wrong and one bad run can end your account. The good news is that the correct size is not a matter of opinion. It is a short calculation from four inputs you already control. This guide walks through it step by step, with a worked example.
Step 1: Know Your Account Balance and Risk Percentage
Begin with two numbers: your current account balance and the percentage of it you are willing to lose on one trade. Most disciplined traders cap risk at 1% per trade; some go to 2%. The lower the percentage, the more losses in a row your account can absorb without serious damage.
Step 2: Convert Risk Percentage Into Money
Turn the percentage into a cash figure. On a 5,000 USD account risking 1%, your maximum loss on the next trade is 50 USD. This is the number every other input has to respect — it is the ceiling on what being wrong can cost you.
Step 3: Set Your Stop-Loss in Pips
Decide where the stop belongs from the chart — beyond a swing high or low, or a multiple of Average True Range — then measure the distance from your entry to that level in pips. Place the stop first, based on the market, and let it drive the size. Never shrink a sensible stop just to justify a bigger position.
Screenshot tip: Use the crosshair tool in MT4 or MT5 and drag from your entry to your stop level. The platform displays the distance in pips directly, so you do not have to count price decimals by hand.
Step 4: Find the Pip Value for the Pair
You need the money value of one pip for the size you intend to trade. For pairs quoted in USD (such as EUR/USD), one pip is worth about 10 USD on a standard lot (100,000 units), about 1 USD on a mini lot (10,000 units), and about 0.10 USD on a micro lot (1,000 units). For pairs where USD is not the quote currency, the pip value shifts with the exchange rate — a calculator handles this for you.
Step 5: Apply the Position-Size Formula
The formula is:
Position size (lots) = risk in money ÷ (stop-loss in pips × pip value per lot)
Worked example: 50 USD risk, a 25-pip stop, and a standard-lot pip value of 10 USD. The denominator is 25 × 10 = 250 USD of risk per standard lot. So 50 ÷ 250 = 0.2 lots. Trading 0.2 lots on a 25-pip stop keeps your loss at roughly 50 USD if the stop is hit — exactly your 1% limit.
Notice how the stop drives everything: tighten the stop to 10 pips and the same 50 USD risk allows 0.5 lots; widen it to 50 pips and you can trade only 0.1 lots. The money-at-risk stays fixed while the size flexes.
Step 6: Round Down to a Safe Lot Size
If the formula produces an awkward figure such as 0.27 lots, round down to 0.2 rather than up to 0.3. Rounding down keeps your actual risk just under your limit; rounding up quietly pushes you over it. Small discipline, compounded over hundreds of trades, is what protects the account.
Step 7: Verify With a Position-Size Calculator
Cross-check the number with a position-size calculator — most regulated brokers provide one, and reputable third-party tools exist too. Enter your account currency, balance, risk percentage, the pair and the stop distance in pips. If the calculator and your manual figure disagree, find out why before you trade.
Screenshot tip: Bookmark your broker's position-size or trader's calculator page. Running the numbers before every trade takes seconds and removes the temptation to "eyeball" a size that is really just the size you wish you could trade.
Step 8: Re-Check When Balance or Volatility Changes
Position sizing is not set-and-forget. As your balance grows, 1% is a larger cash figure, so your sizes can grow with it; as it shrinks, they should shrink too. And when volatility rises — around major news, for instance — a sensible stop has to be wider, which means a smaller position for the same money-at-risk. Keeping the cash risk constant while the size adapts is the whole discipline.
The Takeaway
Correct position sizing turns risk from a feeling into a number. Decide the cash you are willing to lose, place the stop where the chart says it belongs, and let the formula set your lot size. Do that on every trade and you give a good strategy the time it needs to work.
Risk Disclaimer
CFDs are complex instruments and come with a high risk of losing money rapidly due to leverage. Between 65% and 82% of retail investor accounts lose money when trading CFDs with these providers. Correct position sizing limits but does not eliminate risk — slippage and gapping markets can produce losses larger than planned. This tutorial is for informational purposes only and does not constitute financial advice.
