Direct answer
In forex, “commission vs spread” describes two common pricing models for the cost of trading. In one model, you pay a commission (often per trade size) and the price you receive already reflects a spread. In the other model, you pay no explicit commission, but the provider’s spread (the difference between the buy and sell quotes) becomes the main cost component. In both cases, the relevant idea is the same: your execution is affected by how costs are applied, and the total cost depends on trade size and the conditions at execution.
Because providers and account types differ, the key is to separate stable mechanics (what commission and spread mean) from variable conditions (what spread is at the moment you execute, and what the provider charges). This article explains the mechanics, inputs, outputs, and a verification approach without assuming a particular result.
Mechanism and definitions
What “spread” means
The spread is the difference between a quoted buy price and a quoted sell price for the same currency pair. When you buy, you typically enter at the buy quote; when you sell, you typically enter at the sell quote. That difference is effectively paid as part of the execution price.
A practical way to think about spread cost is:
- For a trade that moves “nothing” immediately after entry, you still start with a small unrealized loss because the buy and sell levels are not the same.
- The monetary impact depends on the pair’s quote conventions and your position size.
What “commission” means
Commission is an explicit fee charged by the provider, often stated per lot, per unit of traded volume, or per side (entry and/or exit). Whether it is charged “per trade,” “per side,” or according to tiers can differ by account.
A practical way to think about commission cost is:
- You can calculate commission if you know the fee schedule and the trade size.
- Commission is generally not affected by the immediate spread at the moment of execution, but it is affected by whether it is charged per side and by your traded volume.
How the two can coexist
Some setups charge commission and also include a spread. In that case, you typically pay both: an execution price impacted by spread, plus an additional commission fee.
Evidence or example (with explicit assumptions)
This section uses simplified numbers to show how to compare models. It does not assume live quotes, a specific provider, or a guaranteed relationship.
Assumptions for the example
- You trade a single round-trip: one entry and one exit.
- You measure costs at execution using an “at entry” spread estimate that may change before exit.
- Position size is the same in both pricing models.
- Currency conversion effects are ignored for simplicity (real calculations may require them).
Example calculation framework
Define the total trading cost as:
- Spread component (depends on spread at execution and position size)
- Commission component (depends on fee schedule and volume)
Option A: “Spread-only” model (commission = 0)
- Commission paid: 0
- Spread paid: determined by the provider’s spread behavior at entry and exit
- Total cost: spread component only
Option B: “Commission + spread” model
- Commission paid: commission_rate × traded_volume (and possibly × 2 for entry/exit if charged per side)
- Spread paid: determined by the provider’s typically narrower spread behavior
- Total cost: spread component + commission component
Worked illustration
Assume a hypothetical situation where:
- The spread at entry and at exit is the same in both models (for illustration only).
- Option A spread is 1.0 unit (for cost-conversion purposes).
- Option B spread is 0.6 unit.
- Option B commission is a fixed amount per round-trip (for illustration only).
Then:
- Option A total cost ≈ 1.0 + 1.0 = 2.0 spread-units
- Option B total cost ≈ 0.6 + 0.6 + commission_amount
- If commission_amount is 0.8, Option B total ≈ 1.2 + 0.8 = 2.0 (equal totals in this simplified scenario)
The point is not that any model always wins. The point is the comparison method: you add the spread-related cost and the commission-related cost under the same assumptions.
Material limitation: spread can change between entry and exit
Even if you can compare prices at one moment, realized total cost for a round-trip depends on spreads during entry and exit. In fast or volatile conditions, the spread used for your exit may be wider than for your entry, changing the balance between commission-style and spread-style pricing.
Limitations and risks
1) Provider pricing rules vary
Commission can be charged per lot, per side, or with tiered volume discounts, and some accounts may include both commission and spread. If you apply the wrong assumption about “per side” vs “per trade,” your comparison can be materially wrong.
2) Spread is a moving input
Spread is not a constant. Even with the same account type, spreads can widen due to liquidity changes, news, or other execution conditions. Historical comparisons may not predict future relationships.
3) Other costs can exist beyond commission and spread
Some providers may include additional charges (for example, financing-related charges depending on position holding time). These are not part of the commission-versus-spread distinction, but they affect total trading cost.
4) Different instruments and quote conventions change monetary impact
The way spread translates into money depends on contract specifications, quote currency, and how profit and loss are denominated. Two accounts may list “the same spread in pips” but produce different monetary results due to contract sizing and conversion.
5) Execution quality is not captured by the posted spread alone
Even if a provider quotes a certain spread, actual execution depends on order handling and market conditions. Commission-versus-spread comparison can underestimate the role of execution when quotes move quickly.
Verification and next question
To independently verify the relevant facts for a specific account, do this conceptually (without relying on marketing claims):
- Identify whether commission is charged and, if so, the fee basis (per lot, per unit volume, per side, and any tiers).
- Obtain the typical spread behavior or fee schedule details for the instruments you care about.
- Use the same trade size, the same round-trip structure (entry + exit), and clearly state how you handle spread changes.
- Compute total cost as spread-impact + commission-impact, then compare under the same assumptions.