United buy-miles promotion: Get a 40% discount

Editor's note: This is a recurring post, regularly updated with the latest promotion.

United is offering a 40% discount on mileage purchases. You can take advantage of this promotion by heading to United's buy miles page and logging into your MileagePlus account. But before you do that, let's take a closer look at the promotion and see if it's a good deal.

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Buying United Miles with a 40% discount

This time around, United is offering a 40% discount on all mileage purchases. This lowers the price of United miles to 2.26 cents apiece, which is still 0.96 cents per mile more than TPG's most recent valuation. The discount is valid on all purchases of 1,000 miles or more.

To purchase miles, head to the United Airlines Buy Miles page and enter your United loyalty number and password. Just remember United's restrictions for purchasing miles:

• You can only purchase up to 175,000 miles per account per calendar year (including bonus miles)
• Miles may take up to 48 hours to post to your account
• Purchased or gifted miles don't count toward United elite status

This promotion expires at 11:59 p.m. CT on May 10, 2021.

Related: How to redeem miles with the United MileagePlus program

Other ways to earn United miles

Also, keep in mind that United miles are some of the easiest to earn. You can earn them with a United cobranded credit card or by transferring miles from Chase Ultimate Rewards. Here are some of the best credit cards to use if you want to quickly earn United miles:

• United Explorer Card — Earn 50,000 bonus miles after you spend $3,000 on purchases in the first three months your account is open.
• Chase Sapphire Preferred Card — Earn 60,000 bonus points after you spend $4,000 in the first three months from account opening. (transfers to United at a 1 to 1 ratio)
• Ink Business Preferred Credit Card — Earn 100,000 bonus points after you spend $15,000 on purchases in the first three months of account opening. (transfers to United at a 1 to 1 ratio)

When should you consider buying United miles?

You should only purchase miles through this promotion if you have already found a flight you'd like to book with open award space. That said, this isn't the best deal we've seen for United miles. Last year the airline offered a 100% bonus to targeted customers. We recommend waiting until a better deal rolls around unless you need to book an award ticket now.

However, if you're ineligible for a welcome bonus and have an immediate need for United miles, you may find that you can travel for cheaper by buying miles. TPG currently values United miles at 1.3 cents each — that's significantly lower than the price you'll pay with this sale, but that doesn't necessarily mean it's a bad deal in all cases.

For example, you can book a round-trip ticket from Newark (EWR) to London (LHR) in United Polaris business class for 120,000 United miles on most dates with saver award space. A business-class seat on this route usually costs around $3,500 round-trip on United, but if you were to buy 120,000 miles with this promotion, you'd spend $2,709. This gives you a savings of just over $790 when purchasing miles.

Related: Best sweet spots with United MileagePlus

Use a travel credit card for your purchase

Note that when you buy United miles, you're actually making a purchase with Points.com. Transactions through this merchant don't code as travel, so you won’t earn bonus points with most cards. However, some United cobranded credit cards — such as the United Explorer Card — earned 2 miles per dollar in TPG tests.

You should also consider The Blue Business® Plus Credit Card from American Express (2x Membership Rewards points per dollar on the first $50,000 in purchases per calendar year; then 1 point per dollar, terms apply) or the Chase Freedom Unlimited, with 1.5% cashback — which you can also transfer to an Ultimate Rewards-earning card, effectively earning 1.5 Chase Ultimate Rewards points per dollar.

Additional reporting by Benji Stawski, Victoria Walker and JT Genter.