“Not to be sneezed at” means worth taking seriously: something is valuable, impressive, or useful enough that you should not dismiss it.
The expression comes from an older figurative use of sneeze at, meaning to treat something with scorn or contempt. In simpler words, it meant looking down on something as unimportant. Adding not turns that idea around: this is something you should not look down on.
Today, the expression often describes money, achievements, advantages, and opportunities. It can acknowledge that something is worthwhile even if it is not enormous or perfect. The wording is figurative; it has nothing to do with whether something actually makes you sneeze.
- “A ten per cent discount is not to be sneezed at.” The saving is worth having, even if the price is still fairly high.
- “Finishing third in a national competition is not to be sneezed at.” Third place is an achievement that deserves respect.
- “The job includes free accommodation, which is not to be sneezed at.” The accommodation is a useful benefit worth considering.
You may also see the shorter form not to be sneezed at after a noun: “That is a benefit not to be sneezed at.” Both patterns express the same idea. In everyday conversation, simpler alternatives include worth considering, quite impressive, or nothing to dismiss, depending on the situation.