Hey there, you're reading an outdated post! The updated series from April 2015 can be found here.

This is the twenty-ninth post in a monthlong series. Each post will take about two minutes to read and may include an action item that takes the reader another two minutes to complete.

This is a blog about frequent flier miles. Almost everything I write is designed to help you accumulate miles and points efficiently then redeem them for free travel--up front if possible.

But sometimes using points for a ticket is a huge mistake. Sometimes, just book with cash. JBWC. I'll give two examples, and I'll tell you how to figure out whether you should book with cash or miles on a particular trip.

LAX to Honolulu

The first example comes from yesterday.

This post is part of a four-part series. In Part 1, we looked at the mechanics of the United Mileage Plus program. In Part 2, we looked at the chart and rules to find valuable awards. In Part 3, we’ll value specific Mileage Plus awards. In Part 4, I’ll put a number on one Mileage Plus mile.

Now that we've looked at the rules of the Mileage Plus program, and we've looked at the chart to find some valuable awards, we're going to value specific awards.

Update April 1, 2014: This post was written before Southwest's massive devaluation. Now you need 70 points per dollar for Wanna Get Away? fares instead of 60. Now Rapid Rewards are worth about 1.45 cents each.

Southwest Airlines Rapid Rewards points are worth 1.69 cents per point. Unlike my calculation of the value of an Avios, the valuation of a Rapid Rewards point does not change based on where you live or your flying preferences because Rapid Rewards is a fixed-value award program.

In Part 1, we looked at the mechanics of the Avios program and how it compared to the AAdvantage program (another oneworld program.) In Part 2, we built on the rules of the Avios program to discover what awards they imply are the best values. In Part 3, we’ll value specific Avios awards. In Part 4, I'll put a number on an Avios.