CFD Position Sizing
CFD position sizing determines how many units or contracts to trade from a cash risk budget, a stop distance and the value of each price movement. The calculation works backward from the loss you plan to tolerate, rather than forward from the largest order your available margin allows.
Position sizing is the arithmetic behind your CFD risk management rules. It does not make a trade profitable or guarantee its maximum loss. All examples below are hypothetical; the prices, contract terms and risk percentages are not broker quotes or recommended settings.
The CFD Position Sizing Formula
For a standard CFD whose profit and loss move proportionally with price, start with two calculations:
Cash risk budget = account equity × chosen risk percentage
Position size before costs = cash risk budget ÷ (stop distance × value per point per contract)
Measure the stop distance in the same units as the point value, and express that value in your account currency. The result is the number of contracts. If your platform trades individual units instead, use the value per point for one unit.
The order matters: establish a defensible exit level, then calculate the size that fits it. CME Group’s position sizing guidance uses these same starting points: the stop location and the amount of account capital the trader is prepared to risk.
Do not move the stop closer simply to accommodate a larger order. That changes the trading decision to satisfy the calculator.
Choose a Cash Risk Budget
Use current account equity rather than your original deposit. Account equity includes the account balance and unrealized profits or losses, so it reflects open positions as well as completed trades.
Suppose equity is $20,000 and the chosen risk fraction is 0.5%:
$20,000 × 0.005 = $100 planned risk
This means allocating $100 to the estimated loss if the trade fails under your assumptions. It does not mean buying $100 of exposure or depositing $100 of margin.
No percentage is automatically safe. Even the familiar 2% rule is a convention, not a proven boundary between sensible and excessive risk; CME Group explicitly describes that threshold as arbitrary. Set the fraction within an account plan that addresses losing streaks and simultaneous positions.
Recalculate after account changes. If equity falls from $20,000 to $16,000, a 0.5% budget falls from $100 to $80. Continuing to risk $100 would increase the fraction to 0.625%, even though the cash amount looks unchanged.
Worked Example: Sizing an Index CFD
Assume an index CFD has the following hypothetical terms: each full contract is worth $1 per index point, and the platform accepts quantities in increments of 0.1 contracts.
You plan to buy at an executable price of 6,000, with a stop intended to close the position at 5,960. The distance is 40 points. With the $100 budget above:
$100 ÷ (40 × $1) = 2.5 contracts before costs
That quantity leaves no room for charges or worse execution. Suppose you reserve $10 for estimated charges and adverse slippage at the proposed size. The calculation becomes:
($100 − $10) ÷ (40 × $1) = 2.25 contracts
Round down to the permitted increment: 2.2 contracts. The price loss at the intended stop is $88. Adding the $10 allowance gives an estimated loss of $98.
The table shows how changing the stop distance changes the quantity while retaining the same budget and assumed allowance.
| Stop distance | Calculated contracts | Contracts rounded down | Price loss at stop | Loss including allowance |
|---|---|---|---|---|
| 20 points | 4.50 | 4.5 | $90 | $100 |
| 40 points | 2.25 | 2.2 | $88 | $98 |
| 60 points | 1.50 | 1.5 | $90 | $100 |
The $10 allowance is an illustration, not a universal buffer. Recheck it for each quantity because charges and the cash effect of slippage can change with size. Any slippage allowance can also be exceeded.
Check Contract Size and Account Currency
A quantity field is not meaningful without its contract terms. Before calculating, confirm the contract multiplier, point or tick value, profit currency, minimum quantity and permitted size increment. Broker documentation separates these details: IG’s market specification fields, for example, distinguish contract size, currencies, minimum deal size and stop distance requirements.
If a hypothetical gold contract represents 100 ounces, a $1 move per ounce changes its value by $100. Trading 0.1 contracts would represent 10 ounces, not 0.1 ounce. Confusing those quantities makes every later calculation wrong.
Share CFD Example
Assume one CFD unit represents one share. An executable entry at $50 and an intended stop exit at $48.50 create $1.50 of price risk per unit. With a $100 budget and a $10 allowance:
($100 − $10) ÷ $1.50 = 60 units
The exposure is $3,000, while the price loss at the intended stop is $90. These are different measurements. The price-change-times-quantity arithmetic is illustrated in CMC Markets’ CFD calculation examples.
Convert the Point Value Before Sizing
If the product’s profit currency differs from your account currency, convert the risk before dividing. CMC Markets’ pricing documentation explains how product-currency profit and loss is converted into account currency.
At a hypothetical exchange rate of $1.10 per euro, a contract worth €1 per point is worth $1.10 per point in a dollar account. A 40-point stop therefore represents $44 per full contract, not $40. Allow for conversion charges and rate changes where applicable.
For currency CFDs quoted in pips, use the corresponding pip value. The forex position sizing calculation covers that convention separately.
Include Costs Without Counting the Spread Twice
A more complete check is:
Estimated loss = quantity × stop distance × point value + charges + slippage allowance
Select a permitted quantity whose estimated loss stays within the budget. Charges may include opening and closing commissions, financing over the intended holding period, and any guaranteed stop premium. IG’s CFD charges schedule also illustrates why minimum commissions matter: reducing a share CFD position does not necessarily reduce its commission proportionally.
Handle the spread consistently. If a long trade’s distance runs from the actual buying price to the expected selling price at exit, that difference already reflects the relevant bid and ask prices. Adding the same spread again would double count it. If you start from chart midpoint prices instead, first translate them into executable entry and exit prices.
This distinction is especially useful with tight stops, where a small pricing mismatch can consume a large part of the budget.
Calculate charges again after rounding the position size. If the allowance no longer covers them, reduce the quantity further. If charges alone consume the budget, reject the trade. The broader CFD trading costs guide covers the individual fee types.
Check Margin After Calculating Risk
Margin answers whether the account can support a position. It does not tell you the appropriate position size. As CMC Markets explains in its margin calculation guide, the required deposit depends on the trade’s value and applicable margin terms.
Return to the index example. At 6,000, with $1 per point per full contract, 2.2 contracts represent $13,200 of exposure. Under a hypothetical flat 5% margin rate:
$13,200 × 0.05 = $660 initial margin
The $660 deposit is neither the $88 intended stop loss nor a maximum possible loss. If the margin rate were 10%, the deposit would become $1,320, but the same 40-point move would still produce an $88 price loss.
Leave room for adverse movements and other open positions. A provider can close positions when account funding becomes insufficient, as described in IG’s margin call policy. Review CFD margin requirements separately rather than treating available margin as a spending target.
Account for Gaps and Changes to the Stop
An ordinary stop does not guarantee its execution price. A guaranteed stop can protect the chosen exit level where offered, subject to its terms and premium. IG’s explanation of stop order types distinguishes these protections.
If the index example exits 70 points below entry rather than 40, the price loss on 2.2 contracts becomes $154 before other charges. The original $100 budget has not prevented that outcome. It was a planning constraint, not insurance.
Consider reducing the position or avoiding the trade when a plausible gap would create an unacceptable loss. A small execution allowance should not be treated as protection against every market event. The separate guide to CFD stop-loss orders and guaranteed stops covers those choices.
Recalculate whenever the planned entry or stop changes. Widening the example’s stop from 40 to 60 points while retaining 2.2 contracts raises the intended price loss from $88 to $132. Do not assume the original size remains valid after changing the trade.
Size the Combined Exposure, Not Just Each Ticket
Several individually acceptable trades can create an unacceptable combined loss. CME Group’s trade planning guidance treats maximum account exposure and the number of simultaneous positions as separate decisions from risk per trade.
Three new positions, each carrying $100 of estimated risk, create $300 of combined planned risk. On $20,000 of equity that is 1.5%, before any loss beyond the assumptions.
Also examine what drives those positions. Buying an equity index and several of its large constituents may concentrate exposure rather than spread it. IG’s discussion of CFD portfolio risk explains how positions exposed to the same underlying factor can increase concentration.
Apply the same discipline when adding to a trade. Two entries assigned $50 of risk each use a $100 idea-level budget; opening another ticket does not reset that budget. Recalculate the combined downside using every entry, its quantity, the intended exits and applicable charges.
Validate a CFD Position Size Calculator
Use a calculator to speed up arithmetic, not to choose your risk tolerance. Before relying on its output, check:
- The instrument and contract multiplier match your broker’s product.
- The point value is expressed in your account currency.
- The stop distance uses executable prices and consistent units.
- The result respects minimum quantities and size increments.
- Charges, margin and combined account exposure have been checked separately.
Multiply the proposed quantity back through the stop distance and point value. That reverse check should reproduce the intended price loss.
If the smallest permitted trade exceeds your budget, skip it or assess a genuinely smaller contract. Do not increase the budget simply because the platform will not accept the calculated quantity. The objective is a position that fits the plan, not a calculation that excuses the position.