Experts from AwardWallet and NerdWallet generally recommend buying miles only if: Money + Miles - United Airlines
: Available when booking a flight or through the United My Trips portal, this allows you to buy miles at a potentially lower rate for a specific trip.
: You can typically purchase up to 200,000 miles per calendar year . As of 2026, a newer restriction limits members to purchasing a maximum of 50,000 miles within any consecutive 90-day period .