Free Lot Size Calculator
Calculate the exact lot size for any forex trade. Enter your account balance, risk percentage, and stop loss distance to size your position correctly.
| Type | Lot Size | Units | Pip Value |
|---|
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Lot size tells you how large your forex position should be based on how much you are willing to lose. The formula takes three inputs: your dollar risk, your stop loss distance, and the pip value for the pair you are trading.
Lot Size = (Account Balance × Risk %) / (Stop Loss in Pips × Pip Value per Standard Lot)
The result is expressed in standard lots. One standard lot equals 100,000 units of the base currency. If the formula returns 0.20, you would trade 20,000 units (2 mini lots or 20 micro lots).
Example
Setup: $10,000 account, 1% risk, 50 pip stop loss, EUR/USD
Dollar risk = $10,000 × 0.01 = $100
Pip value per standard lot = $10
Lot size = $100 / (50 × $10) = 0.20 lots (20,000 units, 2 mini lots)
Standard vs Mini vs Micro Lots
Forex trades are measured in lots. Each lot type represents a different number of currency units and produces a different pip value. Here is how they compare:
| Lot Type | Lot Value | Units | Pip Value (USD pairs) |
|---|---|---|---|
| Standard | 1.00 | 100,000 | $10.00 |
| Mini | 0.10 | 10,000 | $1.00 |
| Micro | 0.01 | 1,000 | $0.10 |
Most retail brokers allow you to trade in increments of 0.01 lots (micro lots). This gives you precise control over your risk, especially on smaller accounts.
Why Lot Size Matters
Trading the wrong lot size is one of the fastest ways to blow an account. If your lot size is too large, a normal losing streak can cut your balance in half before you have time to adjust. If it is too small, your winners will barely move the needle.
Proper lot sizing keeps your risk consistent from trade to trade. When you risk the same percentage on every position, no single loss can do serious damage. Over time, this consistency compounds: your account grows steadily during winning streaks and declines slowly during drawdowns.
The key principle is simple. Decide how much you are willing to lose before you enter the trade, then let the calculator work backwards to find the right lot size.
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Frequently Asked Questions
What is a lot in forex?
A lot is the standard unit of trade size in forex. A standard lot is 100,000 units of the base currency. A mini lot is 10,000 units, and a micro lot is 1,000 units.
How do I calculate my lot size?
Divide your dollar risk (account balance times risk percentage) by the pip risk (stop loss in pips times pip value per standard lot). This gives you the lot size that keeps your risk within your target percentage.
What lot size should a beginner use?
Start with micro lots (0.01). This limits your risk to roughly $0.10 per pip, making losses manageable while you learn. Move to mini lots (0.10) once you are consistently profitable.
Does lot size affect pip value?
Yes. One pip on a standard lot (1.00) is worth $10. On a mini lot (0.10), one pip is worth $1. On a micro lot (0.01), one pip is worth $0.10. The lot size directly scales your profit and loss per pip.
What is the maximum lot size I should trade?
Never risk more than 1 to 2% of your account on a single trade. Use this calculator to find the lot size that keeps your dollar risk within that range for any given stop loss distance.