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“Up to” claims like these can be awfully deceptive. When consumer see them, a substantial number think these “up to” claims state an average or even a guaranteed amount that customers will gain, improve, or save. That’s the finding of a recent FTC study that looked at consumer beliefs. The finding has implications for anyone using the words “up to” in an advertisement.

The FTC study involved a fake window company offering a variety of claims, including a claim that its windows would save users “up to” 47% on energy bills. Many potential customers in the study believed that all users, or the average user, would save 47%. In fact, the claim really means that at least one user saved that much, but without proper disclosure it’s unclear what the average user can expect to save–possibly far less.

Although the FTC has not yet broadly policed the use of “up to” claims by advertisers, companies should beware. Now that the FTC’s study has produced a solid basis for enforcement, absent appropriate disclaimers, “up to” claims may now be deemed false or misleading advertisement. From here out, advertisers using the words “up to” should include a disclaimer stating the results that the average user can expect.