How does the MPEP address “about” in numerical range limitations?

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.

How does the MPEP address “about” in numerical range limitations?

The MPEP 2173.05(c) addresses the use of “about” in numerical range limitations. It states:

“The use of ‘about’ in conjunction with a specific number or numerical range in a claim must be evaluated on a case-by-case basis.”

The term “about” is often used to indicate approximate values or ranges in patent claims. Its acceptability depends on:

• The technological facts of the particular case
• Whether the specification provides a standard for measuring the degree intended
• Whether one of ordinary skill in the art would understand what is claimed

Examiners must determine if the use of “about” renders the claim indefinite by considering the context of the invention and the prior art.