Answer

The answer: fix the stop first, then size down to the distance

Sizing a position from a stop-loss takes three steps. First, lock in the stop price from the strategy’s invalidation logic or from volatility. Second, take the absolute difference between the stop and the entry and divide it by the pip/point size to get the stop distance. Third, divide your loss budget by that distance to get a lot, then round down to the lot step. Reverse the order — squeezing the stop toward a lot you already want — and the stop is set by preference rather than by market structure, and control over the loss amount breaks down.

If you want the whole picture of lot sizing first, start with the pillar, the FX & CFD Lot Size Calculation Guide (risk, stop loss, margin and leverage), to see where this lesson fits. How to set the per-trade loss budget itself is covered in the 1% and 2% rules and drawdown article. This piece concentrates on the stretch that comes after the stop is chosen: turning it into a lot.

Basics

Terms and assumptions: pip, point, contract size and distance

Before the arithmetic, here are the terms and the fictional assumptions used throughout the article. Every number below is a fictional educational example, not a live market or a specific broker’s contract specification. Real pip definitions, contract sizes, minimum quantities and lot steps differ by broker, account, instrument and jurisdiction, so always verify your own official contract specification.

• Pip / point: the name for the smallest increment a price moves in. For yen pairs such as USD/JPY, 1 pip = 0.01 is a common convention. Change instrument and the point size changes too (for the units in detail, see the article on lots, units and pip value).
• Contract size (one lot): a common example for a standard forex lot is 100,000 units of the base currency. For gold (XAUUSD) or index CFDs, one lot means something different, so verify those separately in the XAUUSD lot-size guide and the CFD point-value guide.
• Value of one pip/point per lot: how much profit or loss changes when the price moves one pip while you hold one lot. In this article’s fictional example, one standard lot is assumed to be worth 1,000 JPY per pip.
• Distance: stop distance is always the absolute value of the price difference. Long or short, risk is calculated from the unsigned distance.

The worked examples reuse one consistent fictional dataset. Account balance 500,000 JPY, a per-trade loss budget of 1% of the balance = 5,000 JPY, the instrument USD/JPY (1 pip = 0.01, one lot worth 1,000 JPY per pip), and a lot step of 0.01. Every table, figure and mini-calculator default below matches these assumptions.

Formula

Finding stop distance in pips from entry and stop prices

The starting point is converting the gap between two prices into pips. The formula is the same regardless of direction: divide the absolute price difference by the pip/point size.

Substituting the fictional example: for a long (buy) with entry 150.200, stop 149.700 and a pip size of 0.01, the price difference is 150.200 − 149.700 = 0.500. Dividing by 0.01 gives 50 pips.

A long stop sits below entry and a short stop sits above it. For a short with entry 149.700 and stop 150.200, the signed difference is −0.500, but the distance is the absolute value 0.500 = 50 pips, exactly the same. If the direction is inconsistent (for example, a long with the stop above entry) the level is not a valid stop, so the mini calculator below treats it as an input error.

Once distance is known, the lot is the loss budget divided by (distance × per-pip value). The full formula that derives a lot from account balance, loss budget and stop pips is broken down in the forex lot-size formula article. Here the weight is on turning a stop level into a distance.

In the fictional example, 5,000 ÷ (50 pips × 1,000 JPY) = 0.10 lot. Because that is already a multiple of the 0.01 lot step, the rounded lot is also 0.10. The estimated loss is then 0.10 × 50 × 1,000 = 5,000 JPY, landing exactly inside the loss budget.

Structure

Placing a stop from market structure: measure distance from the invalidation point

One leading way to fix the stop price first is to place it from market structure. Put the stop just beyond a recent high or low, a swing point, support or resistance, or the strategy’s invalidation point — the level where “if price breaks here, the idea is wrong.” The entry-to-stop price difference then follows naturally from that invalidation point, which gives it clearer justification than an arbitrary pip count.

For instance, on a long you might treat 149.700, just below the recent swing low, as the invalidation point and place entry at 150.200, making the price difference 0.500 = 50 pips. The key is the order: market structure decides the stop level, and the lot is adjusted afterward to keep the loss amount constant. When the invalidation point is far away the distance widens, and the lot shrinks accordingly.

Note that this article does not recommend any particular trade setup. Which structure counts as the invalidation point varies by strategy, and even on the same chart different traders place stops differently. What is shown here is the order for converting a chosen stop into distance and size, not an entry or exit signal.

Volatility

Setting stop distance from ATR (volatility)

The volatility approach matches stop distance to how much price is moving. ATR (Average True Range) shows the average range over a chosen period; multiply it by a factor to gauge stop distance. Because ATR is expressed in price units, the crucial step is to convert it into pips/points before using it as a distance.

In the fictional example, with ATR(14) = 0.300 (= 30 pips) and a multiplier of 1.5, the stop distance is 0.300 × 1.5 = 0.450 = 45 pips. With a 5,000 JPY loss budget, the raw lot is 5,000 ÷ (45 × 1,000) = 0.111…, which rounds down at the 0.01 lot step to 0.11 lot. The estimated loss is 0.11 × 45 × 1,000 = 4,950 JPY, rounded in the direction that does not exceed the loss budget.

There is no universally optimal multiplier or period. A factor of 1.5 is not a correct answer; it needs adjusting by instrument, timeframe and volatility regime. Even with ATR, it is only material for choosing the stop level, and the steps from there to a lot are the same as in the structure and fixed-distance methods.

Compare

Fixed distance, strengths and weaknesses: comparing three methods

The fixed-distance method commits to “always stop at N pips.” It is fast to decide and easy to record and test. The weakness is that mechanically copying the same pip count across changing volatility or instruments tends to get you stopped out on noise in fast conditions and leaves a needlessly wide stop in quiet ones. Here are the three methods side by side.

What every method shares is the order: stop level first, lot second. Only the way the distance is chosen changes; the formula from distance to lot is identical. Rather than fixing on one method, choose how you set the distance according to the instrument and volatility, then adjust the lot to the resulting distance.

Inverse

Stop distance and lot size are inversely related

The least intuitive part of sizing from a stop is this inverse relationship. As long as the loss budget is held constant, a wider stop means a smaller lot and a tighter stop allows a larger one. Double the stop distance and the lot roughly halves — that is the heart of stop-based sizing. Confirm it with the fictional example (5,000 JPY budget, 1,000 JPY per pip).

What this relationship shows is that a tight stop is not the same as safe. Pairing a tight stop with a large lot makes price noise, spread and slippage weigh more heavily, and you get stopped out sooner than expected. A wide stop keeps the loss amount down by trimming the lot, but it has to be weighed against win rate and profit-taking. You can check the relative impact of costs in the trade cost calculator (spread, commission and swap).

Risk

Gaps, fast markets, slippage and buffers

A point you cannot overlook when sizing from a stop is that a stop order does not guarantee execution at the requested price. On a gap, a spike around an economic release or in thin liquidity, the fill can jump past the stop price and exceed the estimated loss. So do not assume “50 pips = exactly 5,000 JPY, guaranteed.”

In practice, decide a rule for adding a buffer to the estimated loss in advance. For example, cut the lot one step further for positions held over a release, or add the assumed slippage (a few pips in the fictional example) to the distance before computing the lot. What matters is treating the estimated loss as a normal-conditions guide rather than a hard ceiling, and keeping the quantity conservative on the assumption it can be exceeded in adverse conditions.

Mini calculator

Mini calculator: estimate distance and lot

Enter direction, entry, stop, pip/point size, loss budget, per-lot pip value and lot step to estimate the stop distance, raw lot, rounded lot and loss for educational purposes. Inputs are computed in the browser only and are never sent or stored anywhere. First check how the formula behaves in the static example (Table 2), then swap in your own numbers in the tool below.

Workflow

Workflow in the free calculator: the order of inputs

SG Group’s free lot calculator lets you switch between price inputs and a direct pips input. If the stop level is set on the chart, enter prices; if you fix the distance in pips, enter it directly. The input order is these four steps, so you can reproduce the article’s examples under your own account conditions.

On the free plan, for a single position, you get the approximate lot derived from your inputs, the estimated loss and risk percentage at the stop, required margin and margin usage, effective leverage, a reverse check for a chosen lot, estimates for FX/CFD/XAUUSD/index/crypto CFDs, and result sharing, copy and save. In reverse-check mode you enter the lot you intend to hold and re-confirm the risk at the stop. When you need to manage aggregate risk and correlation across multiple positions, or the weighted average and total risk of averaging and pyramiding, that is where the Pro features start to help (you can confirm the learning order of each article in the pillar guide).

Pitfalls

Common mistakes

• Choosing the lot first: squeezing the stop toward a lot you already want lets preference, not the market, set the stop, so you get stopped out on noise. Reverse the order.
• Skipping the pip conversion: feeding ATR or a price difference into the lot formula “as a price.” Always convert to pips/points first.
• Reusing the same pips across instruments: mechanically applying a fixed distance to a symbol with different volatility and contract size distorts what the distance means.
• Rounding up instead of down: rounding the lot up to the step pushes the estimated loss above the budget. Rounding down is the default.
• Trusting the fill price: assuming a stop fixes the loss and taking no buffer for releases or gaps. The estimated loss is a normal-conditions guide.

Every one of these is avoided by keeping the order stop first, lot second and by handling distance in pips. How to revisit the loss budget itself during a losing streak is covered in the article on how much to risk per trade.

Checklist

Practical checklist

Here is the practical stop-based sizing routine as a checklist you can run before placing an order.

• Did you fix the stop price first from a structure, ATR or fixed-distance rationale?
• Did you convert the gap from entry into pips/points as an absolute value?
• Is the stop’s direction correct — below for long, above for short?
• Did you compute the raw lot as loss budget ÷ (distance × per-pip value)?
• Did you round down to the lot step in the direction that does not exceed risk?
• Is the result at or above the broker minimum (or possibly not settable)?
• Did you allow a buffer for gaps, slippage and news releases?
• Are required margin, usage and effective leverage reasonable for the account?

Once you have confirmed the single-position steps under your own conditions, the next step is the actual input. When you need aggregate risk and correlation across multiple positions, or ongoing management in the Vault, consider the Pro and Premium features. Other articles are available from the English article library.

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