Broker Position Size Differences

Today we’ll answer the question: “Do position sizes differ from one broker to another?“. Sounds like a simple enough question but it actually comes with some complex implications. In short: yes, different brokers have different ways to calculate what 1 lot is worth on different instruments.

But let’s get into it and really see how these changes might affect you and what you need to do about it.

Why Broker Lot Sizes Differ

In the world of trading, you’d think a lot is a lot is a lot. But that’s not how it works.

Let’s start with forex position sizes:

Most brokers follow the standard:

• 1.00 lot = 100,000 units of the base currency
• 0.10 lot = 10,000 units
• 0.01 lot = 1,000 units

So far, so good.

But as soon as you step outside major forex pairs, things start to drift.

What about position sizes with indices, commodities, and stocks?

There’s no universal standard. Some brokers define:

• 1.00 lot on US100 = $1 per point Others might use $10 per point, or even 1 contract = 1 lot, and that contract could have its own value.
• 1.00 lot of gold on one platform = 100 ounces On another broker, it might be 1 ounce per lot, or 10. And guess what? The margin requirement changes, too.

Even worse… brokers don’t always make this obvious.

You’re just expected to check the specification sheet and figure it out yourself.

Real World Example: Trading Gold

Let’s say you’re trading XAUUSD (gold).

On Broker A, 1.00 lot = 100 ounces.

Each £1 move = £100 P&L.

So if gold moves £10? That’s £1,000 on a full lot.

On Broker B, 1.00 lot = 10 ounces.

Each £1 move = £10.

That same £10 move? Just £100 now.

Same symbol. Same instrument. Very different outcome.

If you placed the same “1 lot” trade on both brokers, thinking the risk was identical, one could wipe out your stop. The other might barely make a dent.

Why This Matters for Risk Management

Let’s be real.. most of us base our trades on risk percentage.

“If I have a £5,000 account, I’ll risk 1% per trade = £50.”

But that only works if your lot size actually reflects your intended risk. If your broker defines lot sizes differently and you don’t adjust, you’re either:

• Risking too much (easy way to blow up your account)
• Or risking too little (which messes up your reward:risk and skews results)

A position that feels “normal” in volume could be 3x larger or 5x smaller than you meant it to be.

Why Do Brokers Have Different Calculations?

There are a few reasons why position sizing varies by broker:

1. Platform differences – cTrader, MT4/MT5, WebTrader, and proprietary platforms often use different sizing conventions.
2. Underlying contract models – Some brokers base their lot sizes on the CFD contract size, others on futures or actual exchange lots.
3. Regulatory jurisdiction – UK/EU-regulated brokers sometimes standardise differently than offshore ones.
4. Target market – Some brokers aim for beginners (with micro/nano lots). Others build for pros, with full-sized contracts by default.

It’s not about trickery. It’s about structure. But you have to know it.

How to Find Your Broker’s Lot Size Definition

Step 1: Open the symbol specification panel

On MT4, MT5 or TradingView:

• Right-click the asset (e.g., US100 or XAUUSD) in the Market Watch window
• Click “Specification”
• Look for Contract Size, Tick Value, and Margin Requirement

Step 2: Check the broker’s website

Look for their “contract specifications” or product sheet. Some will spell it out:

“1.00 lot of GER40 = €1 per point”

Others will make you dig.

Step 3: Use a calculator that accounts for these differences

Use a Position Size Calculator to ensure that you are accounting for differences across brokers and their respective fees.

You choose the instrument, your account currency, broker, stop size, and risk and it tells you the right lot size for that specific asset and sizing model.

Assets Where Lot Sizes Commonly Vary Between Brokers

Asset	What Can Differ	What to Watch For
Gold (XAUUSD)	Ounces per lot (1, 10, 100)	P&L per $1 move can be wildly different
Indices (US30, FTSE, DAX)	Value per point (£1, £10, €1)	Confirm contract size and tick value
Oil (WTI/Brent)	Barrels per contract	Some use 100, some 1, some weird units
Shares	Leverage, margin %, lot sizes	Fractional vs full share sizing
Cryptos	Contract size, tick size	Especially inconsistent between brokers

What Should You Do About It?

If you’re serious about trading, here’s what I suggest:

1. Stop assuming every broker uses the same lot size

Just because it’s called “US100” doesn’t mean it’s $1 per point.

2. Build your process around risk, not volume

Use calculators that let you plug in your stop loss and risk per trade, not just lot size.

3. Use demo accounts to test broker sizing

It’s boring, but placing a few demo trades is the fastest way to see what each point or pip is actually worth.

4. Bookmark your broker’s spec sheet

Especially if you trade commodities or indices. They change more than forex.

Know Your Broker. Know Your Risk.

Trading is hard enough without your broker using different measurements than you expected.

If you size every trade based on habit, not contract size, you’re taking inconsistent risks. And inconsistent risk makes for inconsistent results.

So next time you hit “Buy” or “Sell,” ask yourself:

• What does 1 lot actually mean here?
• How much is 1 pip/point worth?
• What’s my real exposure?

If you don’t know, check. If you’re still unsure, use a calculator that does the heavy lifting.

Because smart traders don’t trade blindly. They know their broker. They know their numbers, and they never let a “lot” become a liability.