What a lot actually is
In forex, the size of a position is measured in lots, and a lot is simply a standardised quantity of the base currency. A standard lot is 100,000 units, a mini lot is 10,000 units, and a micro lot is 1,000 units. Most platforms let you trade in increments as small as 0.01 lots, which is one micro lot, so you are not forced into large positions before you are ready.
Lot size matters because it determines how much each pip of movement is worth. The larger the lot, the more money rides on every pip — which means more profit when you are right and more loss when you are wrong. Choosing the right lot size is therefore not a detail; it is one of the most important decisions in any trade.
Key points
- 1 standard lot (1.00) ≈ $10 per pip on most USD-quoted pairs.
- 1 mini lot (0.10) ≈ $1 per pip.
- 1 micro lot (0.01) ≈ $0.10 per pip.
How pip value is calculated
For a pair where the US dollar is the quote currency (like EUR/USD), pip value is wonderfully simple: it is the lot size multiplied by the pip. A standard lot of 100,000 units times 0.0001 equals $10 per pip; a micro lot of 1,000 units times 0.0001 equals $0.10 per pip. When the dollar is not the quote currency the maths needs a conversion, but most platforms display the pip value for you, so the principle is what matters.
Once you know pip value, profit and loss become arithmetic. A 40-pip winner on half a standard lot (0.50, worth about $5 per pip) is roughly 40 × $5 = $200. The same 40 pips against you is a $200 loss. Nothing about the trade is mysterious once the size is fixed.
Size from your risk, not your hopes
The professional approach reverses the way most beginners think. Rather than picking a lot size and seeing what happens, you decide in advance how much money you are willing to lose on the trade, then work backwards to the size that respects that limit. Your stop-loss distance and your risk budget together determine the position size — the size never comes first.
The formula is straightforward: position size in lots = risk amount ÷ (stop distance in pips × pip value per lot). It looks abstract until you put numbers in, so let's do exactly that.
A complete worked example
You have a $10,000 account and you follow a 1% risk rule, so the most you will lose on this trade is $100. Your analysis says the stop-loss belongs 50 pips away from your entry. On a standard lot each pip is worth about $10, so a standard lot would risk 50 × $10 = $500 — five times your limit.
Divide your $100 risk by the per-lot risk of $500 and you get 0.20 lots. Trading 0.20 lots, each pip is worth about $2, so a 50-pip stop risks exactly 50 × $2 = $100 — precisely your 1%. If the next trade had a tighter 25-pip stop, the same $100 risk would allow a larger 0.40-lot position. The size flexes to keep your risk constant.
Key takeaways
Lots standardise position size, and pip value scales directly with the lot you choose. Calculate your size from a fixed risk amount and your stop distance, never from how confident you feel — that single habit keeps any one trade from doing serious damage to your account. Position sizing is the bridge between a trading idea and responsible execution, and it is the skill that lets a strategy survive a string of losses without blowing up.
Knowledge check
Test what you've learned
1.How many units of the base currency are in one standard lot?
2.With a $10,000 account, a 1% risk rule and a 50-pip stop (≈$10 per pip on a standard lot), what position size keeps the risk at $100?