TradingCalc

Lot size calculator

Enter what you are willing to lose and where your stop sits. You get the exact position size, rounded down to your broker's lot step so the real risk never lands above your target.

Risk
%
Direction
Stop loss
pips
Prop firm limits

Checks the trade against your challenge drawdown. The tighter of the two limits wins: staying inside the daily rule is useless if the overall one is already spent.

Broker settings

Every broker defines its own contract and pip. If the size does not match your platform, adjust these once and save them as a template.

How the lot size is calculated

Position sizing comes down to a single division: the money you accept losing, divided by what one lot loses if the stop is hit. Everything else is conversion.

  1. Risk in money. Balance × risk percentage. A 10 000 USD account risking 1% puts 100 USD on the line.
  2. Stop distance in price. Pips × pip size, or simply entry minus stop. On EURUSD, 20 pips is 0.0020.
  3. Loss per lot. Distance × contract size × the rate from the quote currency to your account currency. On EURUSD: 0.0020 × 100 000 × 1 = 200 USD per lot.
  4. Lot size. Risk divided by loss per lot: 100 / 200 = 0.50 lots. Always rounded down to your broker's step, never up.

Why other calculators give you a different number

The fragile part is the conversion when the quote currency is not your account currency. Take USDJPY with a dollar account: the pip value is 1 000 JPY per lot, and turning that into dollars means dividing by the USDJPY price. Most calculators reach for an external daily rate here. This one uses the entry price you typed, which is your broker's exact rate — on a recent check that was the difference between 0.78 and 0.79 lots, a 1.3% gap that nobody tells you about.

A genuine conversion is only unavoidable on crosses that contain neither of your currencies, such as GBPJPY on a dollar account. In that case a daily reference rate is used, the page tells you so plainly, and you can overwrite it with your broker's own figure.

Contract specifications are not universal

The second reason numbers disagree is that brokers do not define instruments identically. Gold is 100 ounces per lot almost everywhere, but some brokers call 0.10 a pip and others call 0.01 a pip — a tenfold difference. Index contracts range from 1 to 25 units per point. Nothing in the ticker warns you.

So contract size and pip size are editable here, and you can save them as a template. Or sidestep the argument entirely: enter your stop as a price instead of in pips and the pip definition stops mattering, because the loss per lot becomes the price difference times the contract.

Calculators by instrument

Each page carries the contract specification, the pip value at every lot size and a worked example for that specific instrument.

Calculators →

Guides

Guides →

Frequently asked questions

What is a lot in trading?

A lot is the unit a trade is measured in. In forex a standard lot is 100 000 units of the base currency, a mini lot is 10 000 and a micro lot is 1 000. Other instruments use their own contract: gold is 100 ounces per lot, crude oil is 1 000 barrels, and an index is usually one contract per point. That contract size is exactly what turns a price move into money.

How much should I risk per trade?

Most trading education settles on 1% to 2% of the account per trade, and prop firm rules effectively enforce something similar. The logic is survival: at 2% per trade, ten consecutive losses cost you about 18% of the account, which is recoverable. At 10% per trade the same losing streak takes roughly 65%, which in practice is not.

Why does the calculator round the lot size down?

Because rounding up would put more at risk than you decided. If the exact answer is 0.5794 lots and your broker trades in steps of 0.01, the size becomes 0.57 rather than 0.58. Your real risk lands a hair under target instead of over it, which is the only direction of error worth accepting.

Does the pip value change as price moves?

Only when the quote currency is not your account currency. On EURUSD with a dollar account a pip is always 10 USD per standard lot. On USDJPY with the same account the pip value drifts, because the yen amount has to be converted back at the current rate. That is why the entry price matters for those pairs.

Is this calculator free?

Yes, with no account and no limits. Everything runs in your browser, and nothing you type is sent anywhere.

Educational tool. Check the size in your platform before trading; leveraged trading carries a risk of loss.