A limit order is not automatically a maker order
A limit price restricts the price you will accept; it does not necessarily make your order wait. If a buy limit is high enough to match available asks, it can execute immediately as a taker. A sell limit low enough to meet existing bids can do the same.
Coinbase's trading rules distinguish ordinary limit orders from post-only limit orders. Under its rules, post-only is intended to ensure maker treatment rather than allow immediate taking. Always check the exchange's exact behavior when a post-only order would cross the market; a setting that prevents taking also cannot guarantee a fill.
One order can produce fills with different fees
An order can match part of its quantity immediately and leave the remainder resting. Coinbase documents taker treatment for the immediate portion and maker treatment for the portion that later matches from the book. Treating the entire order as one fee category can therefore misstate its actual cost.
For an illustrative $2,000 filled trade value, suppose $500 fills at a 0.20% taker fee and $1,500 fills at a 0.10% maker fee. The respective fees are $1 and $1.50, for a $2.50 total and a 0.125% effective rate. These are example inputs, not quoted exchange fees.
Compare net execution outcomes, not just the fee label
The relevant fee can depend on your account tier, product and venue. Use the rate actually applicable to the intended fills. A lower fee is only one part of the result: waiting for a maker fill can leave an order unfilled or expose it to a changing market.
For a two-leg calculation, enter each leg's own effective fee rather than assuming the same role on both. Keep network withdrawals, financing and execution slippage separate from trading fees. If reconciling a completed order, use the fill history and charged fee amounts; the order type alone does not reconstruct the final total.
Questions about this tool
Can a market order receive a maker fee?
On Coinbase's documented central order book, a market order is a taker order. Other products can have different mechanisms, so use the execution rules and fee record for the specific venue.
Is paying a maker fee always cheaper overall?
A smaller fee does not ensure a better overall result. Fill timing, execution price and the possibility of no fill can matter more than the difference between the two rates.