The number of Delta miles required to buy a ticket varies depending on several factors, including the destination, route, travel dates, and the type of ticket you want to purchase.

Delta offers several ways to redeem miles for flights, including:

1. Award tickets: Delta's award ticket program allows you to use miles to book flights on Delta and its partner airlines. The number of miles required varies depending on the destination, route, and availability.

2. Pay with Miles: Delta's Pay with Miles program allows you to use miles to reduce the cost of a ticket. The value of each mile varies, but generally, you can use 5,000 miles to reduce the cost of a ticket by $50.

3. Upgrade with miles: Delta's Upgrade with Miles program allows you to use miles to upgrade to a higher class of service on eligible flights.

To determine how many delta miles for a free flight, you can search for flights on the Delta website and check the redemption options for the flights you're interested in. Note that the number of miles required can change based on factors such as demand and availability, so it's best to check frequently and book as early as possible to get the best deal. If you want to know more you can read the full blog.