About 1 in 2 UA 2123 flights from Denver arrived 15+ minutes late, diverted or cancelled over the past year (44%); 0.3% were cancelled. The typical flight landed 9 minutes late.
UA 2123: DEN → SFO
Scheduled to leave Denver at 9:10 p.m. local time. Over the past year it arrived on time 56% of the time (306 flights), in line with other UA flights on the route at that hour (59%). Last seen in the data Aug 31, 2026.
Usually United Airlines's last flight of the day from Denver to San Francisco (99% of days). United Airlines's last DEN–SFO flight was cancelled 0.3% of the time, against 0.2% for its earlier ones. If it's cancelled, the next United Airlines flight is usually around 5:15 a.m. the next morning.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 45 | 44% |
| Tuesday | 41 | 80% |
| Wednesday | 44 | 57% |
| Thursday | 43 | 51% |
| Friday | 44 | 48% |
| Saturday | 44 | 75% |
| Sunday | 45 | 40% |
Why it was late
All flights DEN → SFO · Connecting off UA 2123? Check the risk
UA 2123: MCI → DEN
Scheduled to leave Kansas City at 5:10 p.m. local time. Over the past year it arrived on time 64% of the time (272 flights), in line with other UA flights on the route at that hour (66%). Last seen in the data Aug 31, 2026.
Usually United Airlines's last flight of the day from Kansas City to Denver (82% of days). United Airlines's last MCI–DEN flight was cancelled 0.3% of the time, against 0.5% for its earlier ones. If it's cancelled, the next United Airlines flight is usually around 6:00 a.m. the next morning.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 40 | 65% |
| Tuesday | 39 | 67% |
| Wednesday | 39 | 74% |
| Thursday | 38 | 61% |
| Friday | 39 | 56% |
| Saturday | 38 | 61% |
| Sunday | 39 | 67% |
Why it was late
All flights MCI → DEN · Connecting off UA 2123? Check the risk
Questions
How often is UA 2123 from DEN to SFO late?
United Airlines 2123 from Denver, CO to San Francisco, CA arrived 15 or more minutes late, was diverted or was cancelled on 44% of 306 scheduled flights between September 2025 and August 2026. 0.3% were cancelled.
How often is UA 2123 from MCI to DEN late?
United Airlines 2123 from Kansas City, MO to Denver, CO arrived 15 or more minutes late, was diverted or was cancelled on 36% of 272 scheduled flights between September 2025 and August 2026. 0.4% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check United Airlines for today's flight. Method.