A trademark plaintiff can win on liability and still walk away with almost nothing, because the size of the recovery turns on apportionment—the doctrine that confines a money judgment to the profits and damages actually caused by the infringement rather than the defendant's whole business. This guide explains how that limit works under Section 35 of the Lanham Act, 15 U.S.C. § 1117(a), and maps its unusual burden-shifting choreography: the plaintiff proves the defendant's infringement-related sales, those sales are treated as profit until the defendant proves its deductible costs, and the defendant then bears the burden of showing what share of the remaining profit its own brand, quality, and price drove rather than the stolen mark. It works through the two layers of apportionment, the proximate-cause requirement, the 2025 Dewberry limit confining recovery to the named defendant, the deductible-cost rules, the fact-versus-amount distinction that governs when a damages theory is struck as speculative, the alternative measures of lost profits, reasonable royalty, and corrective advertising, and the equitable overlay reshaped by Romag. A fresh worked example and side-by-side practical takeaways close the discussion.