What Is Per Lot Commission?

Direct answer

Per lot commission is a forex trading fee that is calculated per “lot,” meaning per unit of trade size. Instead of charging a flat amount regardless of volume, providers apply a commission rate that scales with how large your position is.

In practice, total trading cost can include several elements (for example, per lot commission, the spread, and sometimes financing-related fees). Per lot commission is only one part of that overall picture.

Mechanism or definition

A “lot” is a standard way to describe position size in forex. While exact lot definitions can vary by provider and account type, the fee logic is the same: commission is charged when you execute trades, and the amount depends on the lot size you trade.

A common way to think about it is:

Commission fee = (commission rate per lot) × (number of lots traded)
If you open and later close a position, commission may be charged on both executions, so it can affect both entry and exit costs.

Stable mechanics you can rely on conceptually:

The commission component is tied to trade size (lots), not only to market movement.
It is typically specified in the provider’s fee schedule, often as a fixed amount per lot or as a rate that can depend on the instrument/account details.

Variable factors that can change the realized cost (without changing the concept):

The provider’s stated commission schedule and how it applies to your account and instrument.
Trade execution details that affect the actual traded size you end up with (for example, rounding of order size).
Other simultaneous costs (such as spread and any financing or platform fees) that combine with commission.

Evidence or example

Because there are no live prices here, any numeric illustration must state assumptions.

Example (assumptions):

Assume a commission rate of X per lot.
Assume you trade 2 lots to open a position, and later trade 2 lots again to close.
Assume commission is charged on both open and close.

With those assumptions:

Commission on opening = X × 2
Commission on closing = X × 2
Total commission across both executions = X × 4

Key point: the commission portion grows with the number of lots and with the number of times you execute chargeable trades. This is why per lot commission is often discussed under “costs,” alongside spread and other fee types.

How this differs from adjacent concepts:

Spread is the price difference between bid and ask; it is not inherently “per lot commission,” even though spread-related cost also scales with trading activity.
Financing-related fees (often associated with holding positions over time) are different from a commission charged per execution.

Limitations and risks

Per lot commission has important limitations as a standalone cost concept:

It does not represent all costs. Even if you know commission perfectly, your total trading cost can still change due to spread, financing/holding costs, and other provider charges.
It depends on assumptions and schedule details. If you use an example commission rate, you must confirm the relevant fee schedule for your account type and the specific instrument you trade.
Failure mode: double-counting or mismatching fee components. A common mistake is to compare commission across providers without checking whether the spread and other fees are included differently, or to assume commission is charged once when it is charged on both entry and exit.
Uncertainty and outcomes vary. The relationship between trading cost components and eventual results depends on market conditions and execution, so historical or theoretical cost comparisons may not predict future outcomes.

Verification or next question

To independently verify per lot commission for a particular setup, check the provider’s fee schedule for:

The commission rate basis (how “per lot” is defined for your account)
Whether commission applies per execution (open, close, and any other chargeable actions)
How commission interacts with other costs (spread and any additional fee categories)

If you want the next step, a useful next question is how per lot commission interacts with the other cost components you see on your trading statement (spread and financing/holding fees), since total cost determines how expensive a trade becomes.