How to know if an airfare is actually a good deal
A low number is not the same as a good deal. The trick is knowing the route's typical range and comparing the all-in cost, not just the headline fare.
Start with the route's normal range, not the number
A fare only means something relative to what the route usually costs. $200 is excellent for Los Angeles to New York and unremarkable for Los Angeles to Las Vegas. Before you judge a price, get a rough sense of the typical band for that specific city pair.
That is the single idea behind a deal score: it compares today's price to the route's recent range so you are reacting to context, not to a big or small number in isolation.
Compare the all-in cost
The cheapest base fare is not always the cheapest trip. A basic fare without a carry-on can cost more once you add the bag you were always going to bring. Add seats and bags to both options before you compare them.
Weigh flexibility against the savings
A fare that holds low across several date pairs is usually a more dependable deal than one that is only cheap on a single awkward day. If you have flexible dates, use them — and if you do not, decide whether the savings are worth the specific times on offer.
Then book without overthinking it
Airfares are dynamic and move with real-time airline and partner availability. Once a fare is clearly below the route's normal range and the all-in cost works for your trip, waiting for a theoretical lower price usually costs more than it saves.