Ontario (ONT) to Denver (DEN) flights
Southwest Airlines, Frontier Airlines, United Airlines fly nonstop from Ontario International Airport to Denver International Airport, with about 55 flights a week in July 2026. The 819-mile flight takes about 2h 11m gate to gate.
- Distance
- 819 mi · 1,318 km
- Flight time
- 2h 11m
- Airlines
- 3
- Seats filled
- 78%
Airlines flying ONT to DEN
| Airline | Flights a week | Aircraft | Passengers (12 months) | Flight time |
|---|---|---|---|---|
| Southwest Airlines | 27 | Boeing 737 MAX 8, Boeing 737-800, Boeing 737-700 / MAX 7 | 169,407 | 2h 7m |
| Frontier Airlines | 14 | Airbus A320neo, Airbus A321, Airbus A320-100/200 | 86,138 | 2h 18m |
| United Airlines | 14 | Boeing 737-800, Boeing 737 MAX 9, Airbus A320-100/200 | 102,221 | 2h 11m |
Airlines are the operating carrier: regional airlines such as SkyWest or Horizon often fly under a larger airline's brand.
ONT to DEN flight schedule
16 flight numbers flew this route in August 2026, 5 of them almost daily. The first usually leaves at 5:00am and the last at 7:56pm. Times are local and can change; check with the airline before you book.
| Flight | Departs | Arrives | Days flown in August 2026 | On time (12 months) |
|---|---|---|---|---|
| UA 2446United Airlines | 5:00am | 8:21am | 31 | 94% |
| F9 1500Frontier Airlines | 6:00am | 9:24am | 31 | 90% |
| WN 319Southwest Airlines | 6:20am | 9:30am | 12 | 100% |
| WN 3539Southwest Airlines | 6:25am | 9:40am | 4 | n/a |
| WN 3074Southwest Airlines | 6:55am | 10:10am | 7 | n/a |
| WN 3075Southwest Airlines | 8:10am | 11:20am | 12 | 100% |
| WN 2239Southwest Airlines | 9:25am | 12:35pm | 4 | n/a |
| WN 1428Southwest Airlines | 10:40am | 1:50pm | 4 | n/a |
| F9 2908Frontier Airlines | 10:49am | 2:10pm | 25 | 80% |
| WN 1082Southwest Airlines | 10:55am | 2:05pm | 8 | n/a |
| WN 3076Southwest Airlines | 12:25pm | 3:35pm | 20 | 50% |
| UA 1263United Airlines | 1:18pm | 4:39pm | 31 | 81% |
| WN 196Southwest Airlines | 1:50pm | 5:05pm | 8 | n/a |
| WN 239Southwest Airlines | 2:00pm | 5:15pm | 12 | 55% |
| WN 1228Southwest Airlines | 5:55pm | 9:10pm | 4 | n/a |
| F9 1262Frontier Airlines | 7:56pm | 11:21pm | 6 | 85% |
Is ONT to DEN on time?
From September 2025 to August 2026, 82% of 2,624 flights arrived within 15 minutes of schedule and 0.4% were cancelled. Flights leaving around 5am were the most punctual (95%), those around 2pm the least (58%). Most delay time was caused by late-arriving aircraft (40%).
| Airline | Flights | On time | Average delay | Cancelled |
|---|---|---|---|---|
| Southwest Airlines | 1,269 | 76% | 14 min | 0.2% |
| United Airlines | 797 | 87% | 11 min | 0.4% |
| Frontier Airlines | 558 | 87% | 14 min | 0.7% |
Airlines as sold: flights operated by regional partners count under the airline on the ticket. Average delay is across all completed flights, early arrivals counted as zero.
On-time arrivals by departure time
| Scheduled departure | Flights | On time, relative | On time |
|---|---|---|---|
| 5am to 6am | 556 | 95% | |
| 6am to 7am | 395 | 90% | |
| 8am to 9am | 197 | 94% | |
| 9am to 10am | 74 | 92% | |
| 10am to 11am | 179 | 83% | |
| 11am to 12pm | 55 | 75% | |
| 12pm to 1pm | 97 | 55% | |
| 1pm to 2pm | 478 | 76% | |
| 2pm to 3pm | 207 | 58% | |
| 3pm to 4pm | 90 | 63% | |
| 4pm to 5pm | 82 | 59% | |
| 6pm to 7pm | 64 | 79% |
Flights by month
| Month | Flights | Flights, relative | Passengers |
|---|---|---|---|
| August 2025 | 251 | 33,106 | |
| September 2025 | 237 | 30,022 | |
| October 2025 | 239 | 32,048 | |
| November 2025 | 222 | 29,549 | |
| December 2025 | 194 | 25,734 | |
| January 2026 | 184 | 24,080 | |
| February 2026 | 169 | 22,677 | |
| March 2026 | 196 | 27,022 | |
| April 2026 | 204 | 28,723 | |
| May 2026 | 242 | 32,233 | |
| June 2026 | 249 | 37,371 | |
| July 2026 | 243 | 35,367 |
Related
Source: US Department of Transportation, T-100 Segment data, August 2025 to July 2026.