Commission is quoted in several ways, which makes broker comparisons confusing. Converting everything to one unit — round-turn cost per standard lot in pips — makes them comparable.
Common formats:
Per side per lot: e.g. $3.50 per side = $7 round turn per 100,000 units.
Per million traded: e.g. $30 per million per side. One lot of EURUSD at 1.10 is about $110,000 notional, so about $3.30 per side.
Account currency: a €3 per side commission on a EUR account differs from $3 on a USD account.
Tiered: lower rates at higher monthly volume.
Converting to pips: on EURUSD, $10 per pip per lot, so $7 round turn = 0.7 pips. On USDJPY, pip value depends on the exchange rate.
Adding the average spread gives the total cost per trade, which is the number that matters.
One detail that tripped me up when converting: per million pricing is charged on notional, so the cost drifts with the rate. At EURUSD 1.17 that same $30 per million comes to about $3.51 per side, not $3.30.
On USDJPY the pip side moves instead. With the pair at 150, a single lot pays roughly $6.67 per pip, so a $7 round turn is roughly 1.05 pips, noticeably more than on the euro.
For my own comparison I build one number per pair, commission plus the median spread during my actual trading window, both in pips. I use the median rather than the advertised average because a few quiet hours drag an average down.
The tiered schedules need a reality check too. If the lower tier starts at 500 lots a month and I trade 180, the headline rate is irrelevant to me.
Has anyone found a cleaner way to handle the EUR account case? I just convert at the month's average rate and accept a few cents of error per lot.
