Originally Posted by
rampguy
... I have stored up a ton of United Miles which I keep not using because I am never sure if using them is a good deal
....
And in the meantime, things have likely gotten worse. The best time to use miles is soon, waiting is almost most certainity lead to worse rates.
Originally Posted by
rampguy
... is there some algorithm to figure out if it’s worth using the miles by looking at fare cost (in dollars) vs miles cost (in miles)?
A fare you would pay divided mileage need is labeled as CPM, cents per mile. Years ago the target for business was 2.5 cpm or better, even occasionally 5 cpm. Thos numbers are very rare, close to impossible to get together (hence the comment to use, not sit on miles).1.5 to 2 cpm is still possible. Below 1cpm is considered a bad deal as in many UA miles can be used for 1 cpm in other ways.