€250 cash, or 20,000 miles + €50
The miles save €200 after the €50 award charges. Divide €200 by 20,000 miles: that is €0.01, or 1 euro cent, per mile.
(€250 − €50) ÷ 20,000 = €0.01 per mile
If you hold 15,000 miles, you are 5,000 short. Include the cost of any top-up before deciding. Buying more miles can erase the saving.