Flow batteries are a promising grid-storage technology that is scalable, inherently flexible in power/energy ratio, and potentially low cost in comparison to conventional or “static” battery architectures. Recent advances in flow chemistries are enabling significantly higher energy density flow electrodes. When the same battery chemistry can arguably be used in either a flow or static electrode design, the relative merits of either design choice become of interest. Here, we analyze the costs of the electrochemically active stack for both architectures under the constraint of constant energy efficiency and charge and discharge rates, using as case studies the aqueous vanadium-redox chemistry, widely used in conventional flow batteries, and aqueous lithium-iron-phosphate (LFP)/lithium-titanium-phosphate (LTP) suspensions, an example of a higher energy density suspension-based electrode. It is found that although flow batteries always have a cost advantage ($ kWh−1) at the stack level modeled, the advantage is a strong function of flow electrode energy density. For the LFP/LTP case, the cost advantages decreases from ∼50% to ∼10% over experimentally reasonable ranges of suspension loading. Such results are important input for design choices when both battery architectures are viable options.