Denver to Seattle

What the Data Says About DEN to SEA

The Denver to Seattle corridor (DEN → SEA) covers roughly 1,024 miles and is served by 34 carriers, based on Bureau of Transportation Statistics reporting. Across 37,116 flights in the dataset, this route posts a 77.8% on-time rate with an average delay of 62.9 minutes when flights run late. Over the most recent 24 months of BTS data, 13,122 flights were recorded on this pairing — 102 cancelled (0.8%) and 14 diverted (0.1%). Those baseline metrics tell you what to expect before you book.

Having 34 carriers on the route matters: more carriers generally means more daily schedule options, competitive pricing, and redundancy when flights are cancelled. With 37,116 total flights analyzed, the 77.8% on-time figure is statistically meaningful rather than a small-sample fluke. The 62.9-minute average delay applies only to flights that actually ran late, so it is not the average wait across all departures — the majority of flights on this route depart on time under the BTS definition of a delay (15+ minutes past schedule).

Looking at recent months, Dec 2024 posted the best performance on this corridor at 86% on-time, while Dec 2025 came in at 60% on-time — a 27-point gap between best and worst recent month. For travelers evaluating the DEN to SEA route, the combination of a 77.8% on-time rate, 62.9-minute average delay, 0.8% recent cancellation rate, and 34 available carriers is the concrete summary of what BTS data shows about reliability on this pairing.