Key Takeaways
You can upgrade United’s SFO, Asia flights with MileagePlus miles, but it usually requires a cash co-pay on top. The most common cost is 20,000, 30,000 miles plus $600, $700 if you’re starting in economy.
From Premium Plus, it’s cheaper, around 15,000 miles plus $250, $350. Success depends heavily on the route: Tokyo and Hong Kong often clear, while Singapore and Sydney are notoriously tough. Your fare class, MileagePlus status, and the timing of your request all matter when the system decides who makes it into Polaris.
San Francisco is United’s largest Pacific hub, with daily long-haul departures to Tokyo, Hong Kong, Seoul, Singapore, and Sydney. For many MileagePlus members, the question is whether those hard-earned miles can really get them into Polaris Business Class. The short answer is yes, but the upgrade process isn’t straightforward. Unlike a pure award redemption, mileage upgrades mix points with cash, apply fare-class restrictions, and depend on availability in specific upgrade buckets.
I’ve used miles to secure a Polaris bed on SFO, Tokyo and considered it one of the best redemptions in the program. But I’ve also sat on the waitlist for months on SFO, Singapore without ever clearing. This guide breaks down what actually works if you’re hoping to swap a recliner for a lie-flat across the Pacific.
How United Mileage Upgrades Work
Mileage upgrades on international routes are not free. United uses a hybrid system that charges both miles and a co-pay. From economy, you should expect 20,000, 30,000 miles plus $600, $700 one way. Premium Plus is a far better starting point, requiring only about 15,000 miles and a smaller co-pay of $250, $350.
Your fare class is the hidden variable. Discounted economy buckets like K or L are eligible but almost always fall at the higher end of both miles and cash. Premium Plus fares such as R, O, or A look more expensive at first, but the lower upgrade cost usually makes them the smarter play. One critical rule: Basic Economy tickets cannot be upgraded at all.
Routes and Upgrade Reality
The odds of upgrading out of SFO are not equal across Asia. Tokyo Narita remains the most forgiving. Demand has not fully returned to pre-2020 levels, so upgrades clear fairly often, even for mid-tier elites. Hong Kong is similar, especially on midweek departures.
Seoul can also be friendly, though higher status still makes a difference. By contrast, Singapore and Sydney are uphill battles. Singapore’s 17-hour nonstop attracts both business and leisure demand, and cabins frequently sell out in advance. Sydney combines strong corporate traffic with high leisure demand, leaving very few unsold seats. It is possible to waitlist, but many flyers report sitting in Premium Plus all the way to Australia.
Traveler reports on FlyerTalk and Reddit back this up: Tokyo clears, Singapore almost never does.
How the Waitlist Really Works
Requesting an upgrade doesn’t mean you’ll see it confirmed instantly. Space has to be available in “R inventory,” the specific bucket for upgrades. If not, you go onto the waitlist. That list has its own pecking order: United prioritizes by elite status first, then by fare class, and finally by how early you submitted the request.
This explains why a Premier 1K in Premium Plus often clears ahead of a Premier Platinum in discounted economy. Clearing times are unpredictable. Some travelers see their upgrade processed weeks in advance when seats are released. Others get the news at check-in or even at the gate when an agent reprints the boarding pass with Business on top.
Polaris vs Premium Plus on SFO, Asia
To decide if the miles and cash are worth it, you need to look at what you’re buying. Premium Plus gives you a wider recliner, extra legroom, and upgraded catering. Polaris turns your seat into a 6’6” flat bed, comes with Saks bedding, multi-course meals with wine pairings, and crucially, full access to the Polaris Lounge at SFO.
| Feature | Premium Plus | Polaris Business |
| Seat | Recliner, 38” pitch | Lie-flat, 6’6” bed |
| Lounge Access | No | Yes, Polaris Lounge SFO |
| Meals | Premium economy catering | Multi-course dining |
| Cost to Upgrade | None (base fare only) | 15k, 30k miles + $250, $700 |
On a five-hour hop, Premium Plus is fine. On a 12, 17 hour transpacific, Polaris is the difference between arriving rested or wrecked.
Making the Most of Your Miles
If you want to maximize your chances, start by booking Premium Plus. It raises your waitlist priority and cuts the co-pay nearly in half. Submit your upgrade request as soon as you book, since time of request is part of the algorithm.
Timing matters as well. Midweek flights, particularly Tuesdays and Wednesdays, clear more often than Fridays or Sundays. Avoid the crowded evening banks to Asia, when upgrade lists are longest. And don’t forget to watch R inventory. If you see space open in the United app or via tools like ExpertFlyer, you can often confirm instantly instead of gambling on the waitlist.
Conclusion
Yes, you can upgrade United’s SFO, Asia flights with miles, but it’s not a one-click deal. Expect to pay a co-pay, understand that fare class matters, and accept that certain routes are far more upgrade-friendly than others. For Tokyo and Hong Kong, the system works and can deliver amazing value. For Singapore or Sydney, manage expectations, you may not leave Premium Plus.
Want to see which routes are clearing upgrades this week? Join our Mileage Upgrade Forum where travelers post daily results.
FAQs
How many miles does it take to upgrade United SFO, Asia flights?
From economy, 20,000, 30,000 miles plus a $600, $700 co-pay. From Premium Plus, around 15,000 miles plus $250, $350.
Do all economy fares qualify?
Not all. Discounted economy can be upgraded at higher cost, but Basic Economy is not eligible at all.
When do mileage upgrades usually clear?
It depends. Some confirm months ahead when upgrade inventory opens. Many clear within 72 hours of departure, and some only at the gate.
Which routes clear most often?
Tokyo Narita and Hong Kong are best. Singapore and Sydney are much tougher due to sold-out cabins.
Do upgrades include Polaris Lounge access?
Yes. Once your upgrade is confirmed, you can use the Polaris Lounge at SFO, with sit-down dining, showers, and quiet suites.
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