Direct answer
Per lot commission in forex is a pricing model where a provider charges a commission based on how large your trade is, measured in lots. The key mechanics are: (1) the commission rate is stated for a certain lot size, (2) the number of lots in the order is determined from your position size, and (3) the commission is then calculated from that lot count. The final cost you experience can still vary because other costs (such as spreads and overnight financing charges) may apply alongside commission, and providers may define “lot” and contract details differently.
Mechanism and definition
A “lot” is a standardized unit used to describe trade volume in forex. While the exact contract specifications can vary by instrument and provider, commission-per-lot generally means the fee is proportional to that volume measure rather than to profit or price movement.
A typical per lot commission setup has these components:
- Commission rate: an amount stated per lot for opening trades, closing trades, or both. The fee schedule should specify whether commission is charged on entry, exit, or each side.
- Lot count (trade size): the number of lots in the order. This is determined from your chosen position size relative to the provider’s contract specification.
- Directional or side rules: some schedules treat buys and sells the same; others may state the same rate but still charge separately on both sides.
- Accrual currency and conversion: the commission may be charged in a specific account or settlement currency. If your account currency differs, a conversion may occur, which changes the final amount.
From a calculation perspective, the mechanism is usually linear: commission scales with lots. A generic estimate often looks like:
- Compute lots from your position size.
- Compute commission = (commission rate per lot) × (number of lots) × (number of charged sides).
Because the exact fee schedule can differ by provider and instrument, you should treat any numeric example as dependent on the assumptions you use (especially lot size definition, entry/exit charging rules, and the commission currency).
Inputs, outputs, and a worked cost example
A per lot commission calculation needs clear assumptions. Here is one self-contained example that shows the sequence without assuming any future trading result.
Assumptions for the example
- Commission rate is C per lot.
- The provider charges commission on both entry and exit (2 sides).
- The position size is N lots.
- Ignore other costs for this example (spread and overnight charges), because they are separate fee types.
Example steps (symbolic)
- Entry commission = C × N
- Exit commission = C × N
- Total commission for the round trip = 2 × C × N
Example with placeholder numbers
If C = 5 (commission units per lot) and N = 2 lots:
- Entry commission = 5 × 2 = 10
- Exit commission = 5 × 2 = 10
- Total commission = 20
In real accounts, you must also check:
- Whether the rate is stated “per standard lot” and what that means for the instrument.
- Whether commission is charged per trade, per order, or per side.
- Whether there are minimums, caps, or exceptions in the provider’s fee schedule.
The output you care about is the commission amount applied to your account for the executed trade(s). Even when commission is straightforward, the observed total trading cost also depends on other variable components that can change over time, such as spreads and overnight financing charges.
Limitations and risks
Per lot commission is not the same thing as “total trading cost,” and it is not a guarantee about outcomes. Material limitations and failure modes include:
- Different fee schedules: Providers may define commission per lot differently (for example, entry-only vs both sides). If you assume the wrong charging rule, your cost estimate will be off.
- Undefined or different lot specification: The mapping from “position size” to “lots” depends on instrument contract details. If contract specifications differ, the same position size in your platform could correspond to a different lot count.
- Other costs still apply: Spread and swap/overnight charges are typically separate from commission. Even if commission is per-lot and linear, total costs can be non-linear once you add other fee types.
- Execution and operational details: Commission is based on executed quantities. Partial fills, differing execution quantities, or contract adjustments can change the final commission charged.
- Currency conversion effects: If commission is charged in a currency that differs from your account currency, conversion timing and rates can affect the final amount.
Because these factors are variable across providers, account types, and jurisdictions, an independent verification approach is essential: locate the provider’s official fee schedule for commission-per-lot, and reconcile it with your account statement for past trades.
Verification and next question to check
To verify that you understand per lot commission for a specific account, confirm these items in the provider’s fee documentation and/or platform fee display:
- Commission rate unit: “per lot” plus the relevant lot definition.
- Charged sides: entry only, exit only, or both.
- Instrument applicability: the rate may differ by currency pair or contract.
- Commission currency: how it appears on statements, and how conversion may work.
If you want, the next step is to examine a worked example using your account’s numbers (commission rate, lot size definition, and whether the commission is applied on one or both sides) and compare the calculated amount with a commission line from your trade history.
For more context, you can also read the general explanation and examples in the internal pages titled “what is per lot commission” and “what is a worked example of per lot commission.”