Carrier route record
UAORD→SFO
United Airlines · Chicago to San Francisco
- Flights
- 3,813
- Period
- July 2025 to June 2026
- Share of route
- 68%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on ORD to SFO sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 3,813 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.6%, so United on ORD to SFO runs 8 points behind the country as a whole. Across a thousand flights that is about 78 extra late arrivals.
Key figures
On time
69.8%
Arrivals under 15 minutes late, of 3,772 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.05%
National rate is 1.81%
Whole route
67.6%
Every carrier on ORD to SFO, 5,627 flights
These figures cover 3,813 flights between July 2025 and June 2026. Beyond the headline rate, 12.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
United against every carrier on ORD to SFO
United flew 3,813 of the 5,627 flights on ORD to SFO, most of the route. Its 69.8% on time is 2 points better than the route as a whole, which runs 67.6%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from United at 69.8% to Alaska at 57.4%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 3,813 | 69.8% | 73 min | 1.05% | C |
| American Airlines | 1,764 | 63.2% | 73 min | 1.76% | D |
| Alaska Airlinesthin sample | 50 | 57.4% | 59 min | 6.00% | D− |
Flight by flight
United flight numbers on ORD to SFO
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am646 flights89.1%
- 8am–11am590 flights68.6%
- 11am–2pm512 flights74.4%
- 2pm–5pm952 flights68.0%
- 5pm–8pm700 flights53.2%
- 8pm–5am413 flights67.8%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 53.2% on time, against 89.1% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 952 flights scheduled in it.
Across the year
United on ORD to SFO through the year
June is the worst month at 53.0% on time, 30 points below March, the best at 82.6%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. May was the busiest month here, with 370 flights.
Across the week, Tuesday is the strongest day at 78.4% on time and Sunday the weakest at 65.9%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 83,000 reported delay minutes.
- 37%Late-arriving aircraft
- 33%National Airspace System
- 24%Carrier
- 5%Extreme weather
37% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 83,000 reported delay minutes here, that single category outweighs weather by 7 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 83,094 reported delay minutes.
33% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 27,000 minutes out of 83,000, against a national NAS share of 21%.
Cancellations sit at 1.05% against a national 1.81%, which is ordinary. Diversions add another 0.03%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 1,846 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 78.3% on time across 3,815 flights, 9 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 9 points of difference.
The sample behind these figures is 3,813 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking United on ORD to SFO
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 82.6% on time and June 53.0%, a swing of 30 points. If the dates move at all, move them out of June before you think about anything else. 3,772 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to SFO, every carrier
- United on SFO to ORD, the return leg
- American Airlines on ORD to SFO63.2%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- San Francisco International (SFO) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.