Patent Damages: How Courts Calculate What an Infringement Is Worth

If someone infringes your patent, you can sue — but what can you actually recover? The answer is not simply "lost sales." Federal patent law sets out a specific damages framework, and understanding it changes how you think about your patent portfolio, your licensing strategy, and even how you draft claims. This guide explains how patent damages work without pretending every case is the same.

The Legal Floor: Reasonable Royalty

Under 35 U.S.C. § 284, a patent owner who wins an infringement case is entitled to "damages adequate to compensate for the infringement, but in no event less than a reasonable royalty." That phrase — no event less than — is important. A reasonable royalty is the statutory floor, not a consolation prize.

A reasonable royalty is what a willing licensor and a willing licensee would have agreed to in a hypothetical negotiation at the moment infringement began. Courts and parties use a set of factors — historically drawn from the Georgia-Pacific line of cases — to build that number. Those factors include things like existing royalty rates in the industry, the commercial relationship between the parties, and the portion of the infringing product attributable to the patented feature.

Why "Reasonable Royalty" Is Harder Than It Sounds

The hypothetical negotiation sounds simple but requires real evidence: comparable licenses, expert testimony on the value of the technology, and analysis of what alternatives the infringer had at the time. Courts scrutinize royalty base and royalty rate separately. Royalty base — the revenue pool the rate applies to — is often the bigger fight. If a patent covers one component of a complex product, courts generally require the base to reflect the value of that component, not the entire product price.

Lost Profits: A Higher Bar, Higher Recovery

If a reasonable royalty is the floor, lost profits are the potential ceiling. A patent owner can recover lost profits instead of (or in addition to, for different infringing sales) a reasonable royalty — but only by proving they actually lost sales because of the infringement.

The standard framework requires showing: demand existed for the patented product, no acceptable non-infringing substitutes were available, the patent owner had manufacturing and marketing capacity to meet that demand, and the amount of profit lost can be calculated. Meeting all four elements is genuinely difficult, especially for startups or companies that had not yet launched at the time of infringement.

Enhanced Damages for Willfulness

Section 284 also allows courts to increase damages up to three times the compensatory amount when infringement is willful. Willfulness generally requires showing the infringer knew about the patent and infringed anyway without a reasonable basis to believe their conduct was lawful. This is why patent counsel often advise companies not to ignore demand letters and to document any good-faith opinion they received about validity or non-infringement.

The Apportionment Problem

One of the most contested issues in modern patent damages is apportionment — connecting the royalty or profit figure specifically to what the patent actually contributes. Courts have pushed back on damages theories that attribute the value of an entire product to a single patented feature. This matters for patent strategy: narrow claims covering a core, high-value function are often more defensible in a damages calculation than broad claims that are easy to design around.

Apportionment also affects licensing negotiations. If you plan to license rather than litigate, understanding what your patent's contribution to the overall product value is — and being able to articulate it — makes your licensing position more credible.

Attorney Fees

In "exceptional cases," 35 U.S.C. § 285 allows a court to award attorney fees to the prevailing party. This cuts both ways: a patent owner who pursues a weak case aggressively can be ordered to pay the defendant's fees, and an infringer who engages in misconduct can be ordered to pay the patent owner's fees. Fee awards are not automatic, but the possibility shapes settlement dynamics in almost every patent dispute.

Practical Takeaways

• A reasonable royalty is the minimum recovery in a successful infringement case — not a guaranteed easy win; it still requires expert evidence and analysis.
• Lost profits require proving you actually lost sales, which means documenting demand, capacity, and the absence of acceptable substitutes from the beginning.
• Willful infringement can triple damages, so neither ignoring a demand letter nor ignoring a known patent is a safe business strategy.
• Apportionment means your damages recovery is tied to what your patent specifically covers — another reason claim scope and claim drafting matter beyond just getting the patent granted.
• Attorney fee risk under § 285 influences whether cases settle and on what terms; weak cases carry real cost exposure for the party bringing them.
• Understanding the damages framework before a dispute arises helps you make smarter decisions about licensing, portfolio building, and how you document your commercialization efforts.

This guide is general education, not legal advice, and does not create an attorney–client relationship. For your specific situation, talk to a registered patent attorney.