What is the significance of ‘about’ in patent claims involving ranges?

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 is the significance of ‘about’ in patent claims involving ranges?

The term ‘about’ in patent claims involving ranges is significant because it can affect the interpretation of the claimed range and its obviousness analysis. According to MPEP 2144.05:

“The use of ‘about’ avoids a strict numerical boundary to the specified parameter.”

This means that when ‘about’ is used in a claim, it allows for some flexibility in the range boundaries. The significance of ‘about’ includes:

• It may extend the range slightly beyond the exact numbers stated
• It can affect the obviousness analysis when comparing to prior art ranges
• The exact interpretation may depend on the technology and context of the invention

However, the MPEP also cautions that the use of ‘about’ does not automatically render a claim indefinite. The interpretation of ‘about’ should be based on the understanding of those skilled in the relevant art in light of the specification.