Capital One lists the eight ways to redeem your Capital One Miles. In descending order from most valuable to least valuable, those redemption options are:
Convert Capital One Miles to 17 airline or hotel programs (mostly 1:1 transfers).
Book a trip through Capital One Travel (1 cent per mile).
Cover travel purchases recently charged to your card (1 cent per mile).
Get gift cards (between 0.8 and 1 cent per mile).
Redeem through PayPal (0.8 cents per mile).
Shop with Amazon (0.8 cents per mile).
Redeem for cash back rewards (0.5 cents per mile).
Last but not least, you can transfer rewards to another one of your Capital One accounts. You'll get 1 Capital One mile per 1 Capital One mile transferred. Or, if your card earns cash back, you can transfer cashback earnings to another cashback card or to a miles-earning card. More on that option later.