United credit cards increase welcome bonus: New cardholders can earn up to 100,000 miles

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Airlines have been running a slew of promotions this year to get customers onboard and in the air, and that's one reason we've been seeing huge welcome bonuses on co-branded credit cards.

Now, Chase is boosting the welcome bonuses on its United Airlines' co-branded credit cards — with one of the offers reaching an all-time high.

Chase increased the welcome bonuses on these three cards:

• United Club℠ Infinite Card
• United℠ Explorer Card
• United Gateway℠ Card

These cards also come with a handful of benefits that are great for frequent United flyers, like free checked bags (for the Explorer and Infinite card) and access to more award seats on United when booking flights with miles.

Limited-time welcome offer: New United Club℠ Infinite Card cardmembers can earn 100,000 bonus miles after spending $5,000 on purchases in the first three months of account opening.

Select's take: This is the highest-ever public welcome offer for the United Club Infinite Card, and one of the largest bonuses we've ever seen on an airline credit card. You'll have to cough up a hefty $525 for the card's annual fee, but you'll get access to United Club airport lounges around the world. The Infinite card also recently added new benefits to the card, including Platinum status with IHG Rewards (starting in 2022) and a 10% discount on United economy awards when traveling within the continental U.S. or between the continental U.S. and Canada.

Limited-time welcome offer: New United℠ Explorer Card cardmembers can earn 60,000 bonus miles after spending $3,000 on purchases in the first three months of account opening. Plus, you won't have to pay the $95 annual fee in the first year.

Select's take: This isn't a spectacular bonus, but it's respectable, especially since you don't have to pay the annual fee in the first year. If you're a United flyer looking for a personal credit card, this is a solid choice. It's 20,000 miles higher than the previous bonus.

Limited-time welcome offer: With the United Gateway℠ Card, new cardholders can earn up to 20,000 bonus miles after you spend $1,000 on purchases in the first three months of account opening.

Select's take: This United credit card is a good option for those who don't want to pay for an annual fee but still want to collect United miles. This is 5,000 miles higher than the previous bonus.

The United credit cards fall under Chase's 5/24 rule, which means that you can't be approved for one if you've opened five or more personal credit cards (from any card issuer) within the past 24 months. For instance, if you've opened two Citi cards, two Amex cards and one Chase card within the past 24 months, then you will likely be denied for a new Chase card until your 5/24 score decreases.

You also won't be eligible for a new cardmember bonus if you've received a bonus for the same card your applying for in the past 24 months. So if you received a bonus for the United Explorer Card in the last 24 months, you will not be eligible for a new bonus on the Explorer card. But if you had signed up for the Explorer Card in the last 24 months and were applying for the United Club Infinite or United Gateway Card now, you would be able to receive a bonus on either of those cards.

United miles can be used for a variety of things like car rentals and hotels, but you'll get the best value when using them to book flights on United or with its Star Alliance partners (including Air Canada, Avianca, Lufthansa, Singapore Airlines and more).

For instance, you can use them to book flights within the U.S. in economy class for as little as 5,000 miles one-way. If you want to venture a little further from home, flights to Caribbean destinations start at 17,500 miles in economy and 35,000 miles in first class.

And if you want to be fancy, you can book international business class flights to Europe or Asia on United in a lie-flat seat, which costs as little as 60,000 or 70,000 miles one-way, respectively.

If you're looking for a travel credit card but want more flexibility with your points, take a look at the Chase Sapphire Preferred® Card, which is currently offering a welcome bonus of 80,000 points after new cardholders spend $4,000 in the first three months of account opening. You can transfer Chase points to United (or one of its 12 other transfer partners) at a 1:1 ratio, meaning you could have 80,000 United miles after earning that welcome bonus.

And if you use those 80,000 Chase points with the Chase Travel Portal, which allows you to book nearly any flight, hotel or rental car, your points are worth 25% more and you can get $1,000 toward travel from the bonus.