Start with the unit, not the headline
A spread is the distance between a bid and an ask. A commission is a separately stated charge. Comparing the two requires a position size, a pip convention and a common account currency. “From” spreads and fee figures expressed in different units cannot establish which account costs less for your own example.
First write the currency pair as base/quote. In EUR/USD the base is EUR and the quote is USD. A position of 100,000 base units and a pip size of 0.0001 has a pip value of 10 USD. This is arithmetic, not a live quote. It says nothing about how far the market may move or how much money an account needs.
A worked comparison with hypothetical inputs
Assume two invented accounts trade the same 100,000 EUR/USD units, with USD as the account currency. Account A has a 1.2-pip spread and no separate commission. Its spread cost is 1.2 × 10 USD = 12 USD. Account B has a 0.3-pip spread and a commission of 3.50 USD per side per 100,000 base units. Its modelled cost is 3 USD spread plus 7 USD round-trip commission, totalling 10 USD.
That two-dollar difference is conditional on every assumption. If Account B’s spread is instead 0.6 pips, its total becomes 13 USD. At that point the comparison reverses. Use the cost calculator to change the inputs rather than treating either account as a winner.
Round-trip commission = per-side charge × 2 × units ÷ commission lot size
Why the model counts one spread
The usual round-trip approximation treats the spread as the gap crossed between buying at an ask and selling at a bid, assuming an unchanged midpoint and an equal spread at entry and exit. It does not add two complete spreads. If entry and exit spreads differ, their half-spreads relative to the midpoint can produce a different realised cost.
A statement’s profit or loss already reflects the execution prices. Do not deduct the same spread again when reconciling a realised trade. The calculator is a comparison model, not a replacement for a broker statement.
Read a commission schedule literally
“Per side” means the opening and closing transaction each attract a charge. “Round turn” normally describes both together, but check the provider’s definition. A rate per 100,000 USD of notional is not necessarily the same as a rate per 100,000 base units. Minimum charges, tiers and rounding can make a linear estimate inaccurate for small tickets.
For each account, record the charge currency, calculation base, whether the number covers one side, and the minimum. If any of these fields is missing, the comparison is incomplete. Our calculator supports a linear per-side charge in account currency per a chosen number of base units; it deliberately excludes other charging models.
What this calculation leaves out
Overnight financing, slippage, currency conversion mark-ups, guaranteed-stop premiums and non-trading fees can change the total. A minimum spread does not describe a typical spread, and an average without its measurement window is difficult to compare. Two averages measured across different sessions may answer different questions.
For a useful record, save the schedule date, entity, platform, account type, pair, size and measurement period. Then add the holding-cost rules if a position could cross a funding boundary. Lower modelled transaction costs do not make a leveraged position suitable or profitable.