A broker that doesn’t charge commissions typically has higher spreads. The opposite is also valid, a broker that charges commissions usually has lower spreads. The first thing that you want to do is to see how much the price needs to move in order to cover the commission that you pay. Then you add that value to the spread that the commission broker charges. You end up with an “increased spread”. And now, you just have to compare the “increased spread”, with the spread of the broker that has no commissions. The one that has a lower value wins!