How are open-ended numerical ranges evaluated in patent claims?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

Open-ended numerical ranges in patent claims require careful analysis for definiteness. The MPEP provides guidance on how these ranges are evaluated:

• Ambiguities can arise when an independent claim recites an open-ended range and a dependent claim sets forth specific amounts that appear to exclude the open-ended component.
• Claims that include theoretical content greater than 100% are not necessarily indefinite if they cannot exist in fact.
• Maximum limits without specified minimums may be acceptable in certain contexts.

As stated in MPEP 2173.05(c): “Open-ended numerical ranges should be carefully analyzed for definiteness.” The MPEP also notes: “It was observed that subject matter which cannot exist in fact can neither anticipate nor infringe a claim.” (In re Kroekel, 504 F.2d 1143, 183 USPQ 610 (CCPA 1974))

Additionally, the MPEP clarifies certain terms: “the term ‘up to’ includes zero as a lower limit, In re Mochel, 470 F.2d 638, 176 USPQ 194 (CCPA 1974); and ‘a moisture content of not more than 70% by weight’ reads on dry material, Ex parte Khusid, 174 USPQ 59 (Bd. App. 1971).”