As of early 2026, the standard price to purchase United MileagePlus miles is 3.5 cents per mile, plus a 7.5% Federal Excise Tax. This means 1,000 miles will typically cost you about $37.63 USD. United often runs "tiered" promotions where you can receive a bonus of 50% to 100% more miles, effectively dropping the price to around 1.88 cents per mile. You must purchase miles in increments of 1,000, and there is usually a yearly limit of 175,000 miles per account. While buying miles is generally not a great value for "building" a balance from scratch, it is a common 2026 tactic for "topping off" an account if you are just a few thousand miles short of a high-value Business Class award ticket. Always check for a "flash sale" before clicking buy, as United frequently targets members with personalized discounts via their mobile app.