your mileage may vary

Definition

It may work differently in your situation, or be different in your experience.

Etymology

The United States Environmental Protection Agency requires all new vehicles to undergo a set of standard emissions tests which simulate city and highway driving. Part of the test measures estimated city and highway gas (petrol) mileage estimates. Since no test can exactly simulate all driving habits and conditions, the actual gas mileage of each vehicle will vary. As a result, when these estimated mileage claims from automobile manufacturers appear in advertisements, they are almost always accompanied with the standard disclaimer “your mileage may vary”.

Example Sentences

• "The battery lasts a day in my phone, but your mileage may vary."
• "When that definition is executed, the metadata for the temporary table is put into your schema (most likely—your mileage may vary), but no space is allocated to hold data."
• "In other words, your mileage may vary and my disk-size figures are just estimates provided for your convenience."