SkyMiles is one of the largest loyalty programs by several metrics, and earning miles is relatively easy. With several co-branded cards and SkyTeam membership, Delta offers plenty of ways to rack up significant balances. However, redeeming with SkyMiles can be challenging, and the best deals are usually far from its own shores, with domestic and US awards closely linked to cash prices. Here's what you need to know about spending SkyMiles.

Flying domestic

Like the other major US airline programs, Delta Air Lines SkyMiles has switched to dynamic award prices linked to cash prices. However, some good domestic awards are still available, with the carrier offering redemptions starting at 4,500 miles for short-haul routes in basic economy. During sales, you can find domestic awards for anywhere between 4,000 and 10,000 miles one-way across the country, but at other times, expect to see SkyMiles prices roughly reflecting the prevailing fare.

A good rule of thumb is that if cash fares are low, you could also secure a good redemption. For example, a one-way trip from Los Angeles to New York would cost $162 on a random weekday in October. However, you could redeem 8,500 SkyMiles + $5.60, offering a value of 1.9 cents per mile, a good redemption.

However, this isn't true for premium cabins. In the same example, the same route in Delta One would cost $1,499 one-way, but the redemption would set you back a massive 117,500 SkyMiles + $5.60, a much weaker 1.2c per mile. While still not terrible, the lack of a base price means that any luxurious travel will be expensive unless booked during a sale, where domestic first class could turn up for as little as 10,000 miles.

Stay informed: Sign up for our daily and weekly aviation news digests.

Get the co-branded credit card

Delta wants to keep its frequent flyers within its fold and heavily incentivizes its American Express co-branded cards. Holders of these cards receive a 15% mileage discount on all Delta flights (no partners), significantly increasing the value of redemptions. Considering how pricey even domestic flights can become with miles, this benefit cannot be underestimated and is one of many ways Delta maintains a loyal customer base.

Each card also comes with a sign-up bonus, kickstarting your mileage earnings and offering a chance to quickly secure a free flight with the carrier.

Partner airlines are key for international routes

Delta has swiftly closed gaps between itself and partner airlines, ensuring minimal divergence, at least on travel to and from the US. This means there's no way to avoid its pricey 320,000 SkyMile roundtrips to Asia by flying, say, Air France or KLM. Partners offer a good chance of finding those 120,000-mile one-ways in business class to Europe and Asia, but even this isn't great value and requires you to shell out plenty.

As One Mile At A Time noted, international routes outside the US are subject to far lower rates and a somewhat fixed-partner chart. For example, you can book from Japan (or anywhere in East Asia) to Australia or New Zealand for just 75,000 SkyMiles in business class with Vietnam Airlines via Hanoi. Similarly, Johannesburg to Paris with Air France will only 85,000 SkyMiles for a long-haul trip in business, showing the best use of the miles is far from where you may have earned them.

Delta has plenty of partners through the SkyTeam alliance and with others such as LATAM, so finding award space isn't always an issue. As an example, I recently booked a one-way trip from London Heathrow to New Delhi on Saudia for just 35,000 miles (+ $150 in taxes and fees) during the peak December travel season, when fares were well over $700 and redemptions scarce.

Be flexible

Of course, most will want to start their trip in the US or at least try out Delta's famed Delta One suites on the A330neo or A350. To do this, you'll have to show flexibility. Roundtrips are a great place to start, allowing you to book for 230,000 miles roundtrip with negligible taxes ex-US. However, if you don't want to part ways with so much, you could keep your eyes peeled for the rare 120,000 SkyMiles one-way long-haul award.

According to UpgradedPoints, Atlanta-Paris, Detroit-Amsterdam, and Minneapolis-London Heathrow are prime targets for the 120,000-mile awards. Notably, partners like Virgin Atlantic, Air France, KLM, China Airlines, Xiamen Air, and several others also offer this availability out of the US. However, if you're transferring points in, there are far cheaper methods to book these routes. Here are some tips when looking for awards:

• The key to finding the best value without charts is to try several searches. Check different routes and dates, looking further ahead to see how pricing can change.
• Delta runs regular mileage sales and promotions that can reduce rates significantly.
• Now that dynamic pricing is used throughout, there are no black-out dates or peak and off-peak periods.
• Prices usually increase within 21 days of departure (known as close-in pricing).
• Check partner flights on the same route, as these could be cheaper. Adding a partner flight to a Delta flight can sometimes reduce the mileage as the pricing method changes.

Upgrading Delta Air Lines and certain partner flights

Using miles for upgrades is another popular use of miles. Since the switch to a revenue-based system, this is generally not very good value with Delta. As with flight awards, there is no fixed upgrade amount, making planning to use these upgrades difficult. There are two main ways to upgrade:

• At the time of booking online direct with Delta Air Lines: When booking flights within the US, the option to upgrade from main cabin to domestic first class may be given. This is simply based on the cash price of the upgrade (usually offered in miles at the rate of one cent per mile)
• Using Global or Regional Upgrade Certificates: This is a separate method to upgrade existing reservations and uses Choice Benefit certificates given to Medallion Diamond and Platinum members. While these are not based on mileage requirements, they require plenty of spending in advance to be unlocked. These can also be used on select partners, including Virgin Atlantic, Air France, and KLM.

Get all the latest aviation news right here on Simple Flying

There is a base value

If all else fails, or you don't want to spend weeks trying to find availability, Delta has set a base value for SkyMiles: 1¢ per mile. This means you can use Cash+Miles on any booking for this value, allowing you to use 100,000 miles to bring down the ticket price by $1,000. While flights are still the best use of SkyMiles, other methods of using miles might make sense for you. Just ensure they are worth more than the 1¢ rate discussed above.

• Delta Vacations: Delta does not offer general hotel or car booking using miles (unlike other programs such as American Airlines AAdvantage). Instead, it has the Delta Vacations program, where miles can be used to buy packages of Delta flights, hotels, and activities. As always, check the value you are getting compared to other options. Delta Vacations options include complete packages to Disney World theme parks – not something offered by all airlines.
• Magazine subscriptions: This is only a small use of miles, but with limited other options, it may be useful. If there is a publication you are interested in, this can be surprisingly good value (many subscriptions are as low as 1,000 miles for a year).
• Gifting miles: This is generally not good value, but you can gift up to 150,000 annually. There is a co-payment to do this (of one cent per mile plus a processing fee), but it could make sense if a friend or family member needs to top up to reach a certain award.

Redeeming miles for flights with Delta Air Lines or its partners remains the best value way to use miles – especially as Delta offers limited alternatives. The lack of tables or clearly defined redemption rates is sometimes challenging. The key is to be flexible and take your time to search widely. Feel free to share your experiences of redeeming miles in the comments.

Source: One Mile At A Time, UpgradedPoints