20% more miles or 5% cash back?

I’m getting ready for a short trip and I recently received the following credit card promotions for two different cards:

• extra 20% more miles if I use the credit card associated with the airline or
• 5% cash back for using purchases on travel (using a credit card not associated with the airline)

So which to choose?  Well, the ticket costs about $

	Ticket = $240.00
20% more miles method	288 miles
5% cash back method	$12.50

So the real question is whether 288 miles is worth $12.50.  At American Airlines, you can buy miles in increments of 1,000 at varying costs.  There’s also a $30 fee/transaction and taxes.

Miles	Cost	estimated cost/mile*	288 miles would cost about
1000	$27.50	.06	$17.28
2000	$55.00	.045	$12.96
3000	$82.50	.039	$11.23
4000	$110.00	.037	$10.65
5000	$137.50	0.36	$10.37
6000	$150.00	0.32	$9.22
7000	$175.00	0.31	$8.93

* I based these calculations on rough estimates of taxes.

So there may no firm answer but since I rarely buy miles, I’m inclined to take the miles instead of the cash back.

Image: Salvatore Vuono / FreeDigitalPhotos.net