This free lot size calculator tells you exactly how many lots to trade based on your account balance, the percentage you are willing to risk, and your stop loss distance. It works for forex pairs, gold (XAUUSD), and stock indices like US30 and NAS100, with no login and no rate feed required.

Key Takeaways

• Lot size should come from your risk, not your gut: divide the dollars you are willing to lose by your stop loss distance times the pip value.
• One tool covers forex pairs, gold, and index CFDs; the pip value field is editable so it matches any broker’s contract specs.
• Risking 0.5% to 2% per trade keeps a normal losing streak survivable; the calculator flags anything above 2%.

How to Use This Lot Size Calculator

Pick your instrument, then enter three numbers: your account balance, the percentage of it you are willing to risk on this one trade, and your stop loss distance in pips or points. The instrument dropdown pre-fills the value of one pip or point per standard lot, and you can edit that field directly if your broker’s contract size differs. Hit calculate and you get the exact lot size, plus the same answer expressed in mini lots, micro lots, and dollars at risk.

Unlike most position size tools, this one does not pull live exchange rates, which means it loads instantly and never breaks when a rate feed does. For USD-quoted pairs like EURUSD the $10 per pip default is exact. For USD-base pairs like USDJPY the true pip value floats with the exchange rate, so treat the $9.10 default as a close approximation and adjust it when precision matters.

What Is a Lot in Trading?

A lot is the standardized quantity you buy or sell in one position. In forex, one standard lot is 100,000 units of the base currency, and smaller contracts scale down from there.

Lot type	Size (units)	Pip value (USD-quoted pair)	Typical user
Standard lot (1.00)	100,000	$10 per pip	Funded and large accounts
Mini lot (0.10)	10,000	$1 per pip	Mid-size retail accounts
Micro lot (0.01)	1,000	$0.10 per pip	Small accounts, new strategies
Nano lot (0.001)	100	$0.01 per pip	Testing with minimal risk

Gold and index contracts use the same idea with different specs. One standard XAUUSD lot is typically 100 ounces, so a $1.00 move is worth $100 and a 0.10 pip is worth $10. Index CFDs like US30 or NAS100 are usually quoted at $1 per point per 1.00 lot, though broker specs vary, which is exactly why the pip value field stays editable.

The Lot Size Formula

The calculator runs one formula: lot size = (account balance x risk percent) / (stop loss distance x pip value per lot). Everything in position sizing reduces to those four inputs. Your balance and risk percent set the dollars you are allowed to lose; your stop distance and pip value convert those dollars into a contract quantity.

Worked Examples

EURUSD with a $5,000 account

Risking 1% of $5,000 is $50. With a 25 pip stop and $10 per pip per lot, the math is $50 / (25 x $10) = 0.20 lots, or 2 mini lots. If the stop widens to 50 pips, the size halves to 0.10 lots; the dollar risk stays $50 either way.

Gold (XAUUSD) with a $10,000 account

Risking 1.5% of $10,000 is $150. Suppose your stop sits $6.00 away, which is 60 pips at gold’s 0.10 pip increment. At $10 per pip per lot: $150 / (60 x $10) = 0.25 lots, or 25 ounces on a 100 ounce contract.

US30 with a $25,000 prop account

Risking 0.5% of $25,000 is $125. With a 100 point stop and $1 per point per lot: $125 / (100 x $1) = 1.25 lots. On index CFDs always confirm the per-point value with your broker before trusting any calculator’s default.

Lot Sizing for Prop Firm Accounts

Prop firm challenges add a second constraint: the daily drawdown rule. If your firm cuts you at a 4% daily loss, three consecutive 2% losses in one session ends the account even though each trade individually looked reasonable. A common fix is to size at one quarter of the daily limit per trade (1% on a 4% rule), which lets you absorb a full losing day without breaching. Our guide to the best futures prop firms breaks down the drawdown rules firm by firm.

Why Position Sizing Matters More Than Entry Signals

Two traders can take identical entries and end the year in opposite places purely on sizing. Fixed-percent risk keeps any single loss small enough that a normal streak of five or six losers, which every strategy produces eventually, drops the account a few percent instead of a few dozen. Sizing also interacts with your reward-to-risk profile: a wider stop needs a smaller position but often survives noise better. Pair this tool with our risk reward ratio calculator to check that the trade is worth taking at all, and browse the full trading calculators suite for related tools.

Leverage, for what it is worth, does not change any of this. Leverage determines the margin your broker sets aside, not your risk; your risk is set by stop distance and position size. A properly sized trade at 1:500 leverage loses the same $50 as the identical trade at 1:30.

FAQ

How big should my lot size be?

Big enough that a win matters and small enough that your stop loss only costs 0.5% to 2% of your account. There is no universal correct lot size; there is only the size that matches your balance, your risk percent, and your stop distance, which is exactly what the calculator above solves for.

What lot size should I use for a $100 account?

At 1% risk you can lose $1 per trade. With a 20 pip stop on a USD-quoted pair that works out to 0.005 lots, which most brokers round to a 0.01 micro lot. Practically, a $100 account should trade micro or nano lots only, and wider stops may not be tradeable at all at 1% risk.

How do I calculate lot size for gold (XAUUSD)?

Select Gold in the instrument dropdown, enter your stop in pips where 1 pip equals a $0.10 move, and use $10 per pip per lot (the standard 100 ounce contract). A $3.50 stop is 35 pips; risking $70 gives 0.20 lots.

Does leverage change my lot size?

No. Leverage only changes the margin required to open the position. Your lot size should come from your risk percent and stop distance. Higher leverage lets you open bigger positions than you should, but it never makes them a good idea.

What is the difference between standard, mini, and micro lots?

A standard lot is 100,000 units of the base currency (about $10 per pip on USD-quoted pairs), a mini lot is 10,000 units ($1 per pip), and a micro lot is 1,000 units ($0.10 per pip). The calculator reports all three so you can place the order in whatever increment your broker uses.