GUIDE • FUNDAMENTALS

What is position sizing?

Position sizing is the process of deciding how big your trade should be before you enter. It is not about confidence, predictions, or how strong a setup looks. It is simply the trade size (lots or units) that keeps your risk controlled if the trade goes wrong.

Most trading accounts do not fail because of one terrible trade. They fail because of a series of normal losses combined with oversized positions. Even a strong strategy can hit a losing streak. Position sizing is what gives your edge time to play out without a single trade (or a short run of trades) taking you out of the game.

Done well, position sizing creates consistency. When every trade risks the same fraction of your account, you stop having one oversized position decide your entire week. You also avoid the opposite problem: trading so small that results feel random and motivation collapses.

Position sizing also forces clarity. To size a trade responsibly, you must define where the idea is invalid, meaning you need a stop loss. If you cannot define the stop, you cannot define the risk. And if you cannot define the risk, you are not position sizing, you are guessing.

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Why it matters

Lower risk of ruin

Smaller, consistent risk per trade makes it harder for a normal losing streak to do permanent damage.

More stable performance

A good month is built from many small decisions, not one oversized gamble.

Cleaner decision making

You size the trade from your stop loss, not from emotion.

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How this calculator works

The calculator follows a simple idea: define the money you are willing to lose on the trade, then solve for the position size that matches that risk if the stop loss is hit.

Step 1: Risk Amount

Account Balance × Risk % = the maximum you are willing to lose on this trade.

Step 2: Pip Value

Convert your stop loss distance into money using the instrument's pip value. If the instrument is quoted in a different currency than your account, the pip value is converted into your deposit currency first.

Step 3: Position Size

Position Size (lots) = Risk Amount ÷ (Stop Loss in pips × Pip Value per 1.00 lot)

Step 4: Broker-ready size

The exact result is rounded DOWN to the nearest volume your broker accepts (minimum lot and lot step), and the calculator shows the actual risk of that executable size. It never rounds up past your target risk.

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Worked examples

Example 1: EURUSD

Account: $5,000 · Risk: 1% ($50) · Stop: 30 pips. For EURUSD, pip value ≈ $10 per pip per lot. Risk per lot with 30-pip stop = 30 × $10 = $300. Position size = $50 ÷ $300 = 0.17 lots (rounded).

Example 2: GBPJPY

Account: $5,000 · Risk: 1% ($50) · Stop: 30 pips · USDJPY: 150. Pip value per lot in USD ≈ 1,000 ÷ 150 = $6.67. Risk per lot = 30 × $6.67 = $200.10. Position size ≈ $50 ÷ $200.10 ≈ 0.25 lots.

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Metals: lots vs. ounces

Metals can look confusing because the word lot does not mean 100,000 units like FX. For metals, a lot is usually defined in ounces.

XAUUSD (Gold)

1.00 lot = 100 troy ounces. 0.10 lot = 10 oz, 0.01 lot = 1 oz.

XAGUSD (Silver)

1.00 lot = 5,000 troy ounces. 0.10 lot = 500 oz, 0.01 lot = 50 oz.

Stop loss on gold

Many platforms quote gold to 2 decimals (1 pip = $0.01). A 20-pip stop is a $0.20 move. A $2.00 stop would be 200 pips. If your platform shows open and stop price, the stop distance is simply the price difference.

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Exact size vs broker-ready size

The mathematically correct position size is often not a size your broker will accept. Brokers only execute volumes on a grid defined by a minimum lot and a lot step, both commonly 0.01. The calculator therefore shows two numbers: the exact calculated size and the broker-ready position.

Exact calculated size

The pure mathematical answer, for example 0.0167 lots for a $100 risk on a $60 gold stop with a 100-ounce contract. It can have more decimals than your broker accepts.

Broker-ready position

The largest valid volume at or below the exact size, for example 0.01 lots with a 0.01 step. Its actual risk ($60 in that example) is shown next to your target risk ($100), so you always see what the executable trade really risks.

Why rounding up is dangerous

Rounding 0.0167 up to 0.02 looks harmless but risks $120 on a $100 target with a $60 gold stop. That is 20% more than you planned. The calculator shows the next valid size and its risk, and warns when it exceeds your target.

Lots vs exposure

Units = lots x contract size. With a 100-ounce contract, 0.0167 lots is about 1.667 oz of gold. With a 10-ounce contract, the same 1.667 oz exposure needs 0.1667 lots. The lot number changes; the exposure does not.

Below the broker minimum

When the exact size is smaller than the minimum lot, no valid position fits your target risk. The calculator shows the risk the minimum lot would carry instead of silently rounding up to it.

Entry and stop prices

You can enter the stop as an entry price and stop-loss price instead of pips. The absolute price difference is converted into the stop distance: on gold, a move from 3350 to 3290 is $60, which equals 6,000 pips at $0.01 per pip.

Tip: Broker contract settings live in MT4/MT5: right-click the symbol and open Specification to see contract size, minimum lot and lot step.
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Common mistakes to avoid

Mixing pip and price stops

Some tools take a stop loss in pips, others take an open price and stop price. Make sure you are comparing the same stop distance.

JPY pip convention

JPY pairs use a pip size of 0.01, not 0.0001. A 30-pip stop on GBPJPY is a 0.30 move in price.

Contract size differences

Some brokers use gold contracts of 100 oz per lot, others use 10 oz or 1 oz. The same lot size can represent a different exposure depending on the broker.

Deposit currency conversion

A pip value can change when your account currency changes. The trade might look larger or smaller only because of currency conversion.

Confusing micro, mini, and standard lots

In FX, 1.00 standard lot is 100,000 units, 0.10 is a mini lot, 0.01 is a micro lot. Metals and indices follow different contract definitions.

Tip: If a result looks too big or too small, check only two things first: (1) contract size, and (2) what the tool means by pip or tick.
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Mini FAQ

Does this work for indices or commodities?

The logic works for any instrument if you know the tick or pip size and the contract specification (what 1 lot represents). Some brokers define metals, indices, and crypto contracts differently, so always sanity-check contract size.

Can I use this with prop firm rules?

Yes. Prop rules are usually based on daily drawdown and maximum loss. Position sizing helps you translate those limits into a consistent per-trade risk.

What risk % do most traders use?

There is no universal best number. Many traders operate somewhere between 0.25% and 2% depending on strategy, volatility, and objectives. Focus on survivability first: smaller risk generally reduces drawdowns and makes losing streaks easier to tolerate.