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Position size & lot size calculator

Start from how much you are willing to lose on one trade, and work back to the lot size. The wider your stop, the smaller the position. It runs in your browser, so there is nothing to download or add to MT4 or MT5.

New to this?

You getThe lot size that keeps the loss at your stop within that amount

↓ See how it is worked out
What to enter, and the terms used

You enterYour balance, how much you are willing to lose on one trade (% of balance or an amount), the pair, your stop loss in pips, and the contract size

A pip is the unit for price moves. For most pairs it is 0.0001; for JPY pairs such as USD/JPY it is 0.01.

New to these words?

Risk per trade
%
pips
Your entries stay on this device only and will be here next time. You can use . or , for decimals. If a number has separators, we show how it was read below the field.

Example: enter this, get this

  1. Account currency: USD, balance: 10,000
  2. Risk per trade: 1% of balance (= $100)
  3. Pair: EUR/USD, stop loss: 20 pips, contract size: 100,000 units

On 1 lot, one pip is worth $10 (100,000 × 0.0001). A 20-pip stop loses $200 per lot. You are willing to lose $100, so 100 ÷ 200 = 0.5 lots. If you trade 0.5 lots and your 20-pip stop is hit, the loss is about $100 (1% of your balance). It can be larger if price gaps or slips past your stop.

The example numbers only show how the calculation works. They are not recommendations. Replace them with your own account’s numbers, or use “Clear inputs”.

Where to find these numbers in MT4/MT5

Balance
In MT4, the Terminal window; in MT5, the Trade tab of the Toolbox, under “Balance”. In the mobile app, on the Trade screen
Stop loss in pips
The gap between your entry price and stop price. For most pairs one pip is 0.0001 (1.0850 → 1.0830 is 20 pips); for JPY pairs it is 0.01. In MT5, one “point” is usually a tenth of a pip at brokers with 5-digit prices
Contract size
Right-click the pair in Market Watch → Specification → “Contract size” (often 100,000 units for currency pairs, but it varies by broker and account)
Account currency
The currency your balance is shown in. If you are not sure, check the account details in your broker’s client area
Decimals (digits)
In the same Specification window, “Digits” is how many decimals the price has. With 5 digits (3 for JPY pairs), the last digit is a point, a tenth of a pip

The mobile app and platforms other than MT4/MT5 may use different names or places (for example, “Units” or “Lot size” for contract size). If you cannot find a number, check your broker’s help pages.

How it works

  1. Lot size = risk ÷ (stop loss in pips × pip value per lot)
  2. Pip value per lot = contract size × pip size, in the quote currency. If that differs from your account currency, it is converted with the rate you enter.
  3. The pip size is 0.01 for JPY pairs and 0.0001 for most others. For gold, enter the stop as a price distance in USD.
  4. The result is rounded down to 0.01 lots, so the calculated loss is at or below the risk you set. Your real loss can be bigger because of price gaps, slippage, commissions and spread.

Formula, a worked example and common mistakes

The formula

Risk amount = balance × risk % ÷ 100 (or the fixed amount you set)

Pip value per lot = contract size × pip size × conversion rate

Lot size = risk amount ÷ (stop loss in pips × pip value per lot), rounded down to 0.01 lots

The conversion rate is how much one unit of the quote currency (the right side of the pair) is worth in your account currency. If they are the same currency, it is 1.

A worked example by hand: EUR/USD in a GBP account, 25-pip stop
  1. Risk amount = 5,000 GBP × 1% = 50 GBP
  2. Pip value per lot = 100,000 × 0.0001 = $10. With GBP/USD at 1.2500: 10 ÷ 1.25 = 8 GBP
  3. A 25-pip stop on 1 lot = 8 × 25 = 200 GBP
  4. Lot size = 50 ÷ 200 = 0.25 lots (the loss at your stop is 0.25 × 200 = 50 GBP)
The numbers only show how the calculation works. They are not recommendations, and the rates are examples.
3 common mistakes
  1. Using the wrong contract sizeIf your account’s lot is 10,000 units instead of 100,000, the same lot size is ten times smaller. Check the contract size in your platform first.
  2. Forgetting to convert to your account currencyFor EUR/USD the pip value comes out in USD. If your account is in GBP, INR or anything else, skipping the conversion gives the wrong lot size.
  3. Rounding upTurning 0.111 lots into 0.12 lots means the loss at your stop is more than you set. This tool rounds down.

Small account examples ($500 and 100,000 JPY)

The math is the same for a small balance. The difference is that the answer is more often below the smallest size you can order. These examples risk 1% of the balance per trade only to show the math; it is not a recommended level (for an account where the minimum is 0.01 lots).

$500 balance, EUR/USD (1 lot = 100,000 units)
  1. 1% = $5. On 0.01 lots, one pip is $0.10
  2. 20-pip stop: 5 ÷ (20 × 10) = 0.025 → rounded down to 0.02 lots (the loss at your stop is $4)
  3. 80-pip stop: even 0.01 lots loses $8 (1.6% of the balance)
  4. On 0.01 lots, a stop of up to 50 pips stays within 1% (5 ÷ 0.1)
100,000 JPY balance, USD/JPY (1 lot = 100,000 units)
  1. 1% = 1,000 JPY. On 0.01 lots (1,000 units), one pip is 10 JPY
  2. 20-pip stop: 1,000 ÷ (20 × 1,000) = 0.05 lots
  3. 150-pip stop: the math gives 0.0066… lots. Even 0.01 lots loses 1,500 JPY (1.5% of the balance), more than 1%
  4. On 0.01 lots, a stop of up to 100 pips stays within 1% (1,000 ÷ 10)

What to do when even the smallest size is above your limit, such as changing the stop or skipping the trade, is up to your own rules. This tool does not decide.

FAQ

How many units is 1 lot?

At most MT4/MT5 brokers, 1 standard lot is 100,000 units of the base currency. Some accounts use other sizes, so check the contract size in your platform.

What % should I risk?

This tool does not pick a number for you. Enter the one from your own rules. The “If this loss repeats” table shows how a losing streak would move your balance.

How do I enter gold (XAU/USD)?

Pick XAU/USD and enter your stop as a price distance in USD. For example, if your stop is $5 away from your entry, enter 5. The contract size switches to 100 oz, but it varies by broker, so check yours. There is also a gold lot size calculator that lets you choose how pips are counted.

Does this work for a small account, like $100 or $500?

Yes. The math is the same. If the answer is below 0.01 lots, the result says so and shows what share of your balance a stop on 0.01 lots would lose. See the small-account examples above.

What lot size goes with a $500 account?

It depends on your stop distance and the risk you set, so there is no single answer. For example, risking 1% ($5) with a 20-pip stop on EUR/USD gives 0.02 lots (with a 100,000-unit lot). This tool does not recommend a risk level.

Is there an MT4 or MT5 download?

Yes. You can use this calculator in two ways. This page is the web version: it runs in your browser, so there is nothing to install. Keep it open next to MT4 or MT5 (it also works on a phone) and enter the numbers from your platform. “Where to find these numbers in MT4/MT5” above shows where each one is, and your entries are saved on this device only. If you would rather do the same calculation on your chart, download the free MT4/MT5 position size indicator. It runs in MT4 or MT5 on a computer and never places trades.

How do I count pips on JPY pairs and 5-digit prices?

On JPY pairs one pip is 0.01, so 150.00 → 149.80 is 20 pips. On most other pairs it is 0.0001. If your platform shows one more decimal (150.000 or 1.08500), the last digit is a point, a tenth of a pip, so 200 points are 20 pips. For the currency pairs in the list, the pip size is set for you.

How much margin will this lot size use?

This tool sizes a trade by risk. It does not check margin. Enter the lot size in the margin calculator to see the margin it needs at your leverage.

Did you stick to the size you calculated?

Tiltnote is a trading journal where you log, in one tap, whether you kept your rules and how you felt on each trade. Over time you can see how the days you stick to your size differ from the days you don’t. Add the EA to MT4/MT5 and closed trades are recorded automatically (paid plan).

Try Tiltnote free →On the free plan, analysis and history show your most recent 14 days (older records are kept and unlock on the paid plan).

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This tool is a calculation aid. It is not investment advice or a recommendation to make any trade. Real values depend on your broker’s contract size, rates, commissions and spread. Always check in your trading platform before placing an order. The numbers you enter are calculated on your device and never sent anywhere.

Updated 22 Oct 2026 · Run by Kenji Okumura, Representative, Tiltnote · About this site