The short answer
A lot is a fixed number of currency units. A standard lot is 100,000 units, a mini lot is 10,000, a micro lot is 1,000 and a nano lot is 100. On EUR/USD those are worth roughly $10, $1, $0.10 and $0.01 per pip. You should never pick a lot size by feel: compute it from the money you are willing to lose and your stop distance, so that lot size is an output, never an input.
What is a lot in forex?
Currencies trade in standardised bundles called lots. Instead of buying “37,500 euros,” you trade a number of lots, and your platform converts that into units behind the scenes. A lot is simply a unit-count label — nothing more mysterious than that.
Lot size matters because it sets how much each pip is worth, and therefore how much you win or lose per unit of price movement. Two traders can take the exact same setup with the same stop, and one risks $5 while the other risks $500 — the only difference is lot size.
The four lot sizes
There are four sizes you will meet, defined by units of the base (first) currency:
- Standard lot — 100,000 units — about $10 per pip on EUR/USD
- Mini lot — 10,000 units — about $1 per pip
- Micro lot — 1,000 units — about $0.10 per pip
- Nano lot — 100 units — about $0.01 per pip (not offered by every broker)
On most platforms lots are entered as decimals of a standard lot: 1.00 is a standard lot, 0.10 is a mini, 0.01 is a micro. So when a platform asks for “volume 0.05,” it means five mini lots, or 50,000 units.
How to size a position from your risk
This is the part that separates traders from gamblers. You do not choose a lot size and hope; you derive it. The formula:
Lot size = (account risk in money) ÷ (stop distance in pips × pip value per lot).
Work top-down. First decide the money you will lose if wrong — a common cap is 1% of the account. Then read the stop distance in pips off your chart. Then solve for the number of lots that makes those two agree. Lot size falls out at the end; you never pick it first.
A worked example
Account: $5,000. Risk per trade: 1% = $50. Trade: EUR/USD, stop 25 pips away.
On EUR/USD a mini lot is $1 per pip, so a 25-pip stop on one mini lot risks $25. You want to risk $50, so you need two mini lots (0.20 on the platform). Check: 2 × $1 × 25 pips = $50. Correct.
Change any input and the size changes: widen the stop to 50 pips and the same $50 risk allows only one mini lot. This is why lot size must be computed per trade, and why a position size calculator is the one tool worth keeping open.
Why beginners should start on micro lots
Micro lots (and nano lots where available) let you trade real money — with real emotions — while keeping the stakes small enough that tuition is cheap. A 50-pip mistake on a micro lot costs $5, not $500. That is the correct price to pay for learning.
The beginner guide recommends trading micro lots until you have 30 consecutive plan-adherent trades. The point is not the size of the profit; it is proving you can follow a process before you scale it.
Common lot-size mistakes
Three errors show up again and again:
- Choosing lots by conviction. “I'm sure about this one” is not a position-sizing input. Certainty is a feeling; risk is arithmetic.
- Fixed lots regardless of stop. Trading 0.10 on every setup means a wide-stop trade risks far more than a tight-stop one. Size to the stop, every time.
- Ignoring the account currency. If your account is not in the quote currency, the pip value — and therefore the correct lot — shifts. Convert first.
Frequently Asked Questions
What is a standard lot in forex?
A standard lot is 100,000 units of the base currency. On EUR/USD it is worth about $10 per pip when your account is in US dollars.
How many units is a mini and a micro lot?
A mini lot is 10,000 units (about $1 per pip on EUR/USD) and a micro lot is 1,000 units (about $0.10 per pip). On most platforms these are entered as 0.10 and 0.01 volume.
What lot size should a beginner use?
Micro lots. They let you trade real money while keeping mistakes cheap — a 50-pip error costs about $5 on a micro lot. Stay on micro lots until you can follow a plan consistently.
How do I calculate the right lot size?
Divide the money you are willing to risk by the stop distance in pips multiplied by the pip value per lot. For a $50 risk and a 25-pip stop on EUR/USD, that is two mini lots.
Is lot size the same as leverage?
No. Lot size is how many units you trade; leverage is how much of that position your broker funds versus your own margin. They interact, but risk is set by lot size and stop distance, not by leverage.