What are “open-ended” numerical ranges 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.

What are “open-ended” numerical ranges in patent claims?

“Open-ended” numerical ranges in patent claims refer to ranges that have only one defined boundary. The Manual of Patent Examining Procedure (MPEP) 2173.05(c) states:

“Open-ended numerical ranges should be carefully analyzed for definiteness.”

Examples of open-ended ranges include:

• “greater than 5”
• “at least 10”
• “below 100”

These ranges are considered indefinite if they don’t have a clear upper or lower limit, potentially making the scope of the claim unclear. Examiners must evaluate whether the specification provides sufficient guidance to determine the boundaries of such ranges.