Route reliability record
ORD→SFO
Chicago to San Francisco
- Flights
- 5,649
- Period
- September 2025 to August 2026
- Distance
- 1,846 mi
- Carriers
- 2
This route draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 5,649 ORD to SFO flights, of which United Airlines flew 3,883 at 69.1% on time.
Best time to fly ORD to SFO: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 89.0% of the time and Tuesday flights 75.7%, against 66.2% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 11 points behind the country as a whole. Across a thousand flights that is about 111 extra late arrivals.
Key figures
On time
66.2%
Arrivals under 15 minutes late, of 5,585 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
1.08%
National rate is 1.89%
Best carrier
United
69.1% on time across 3,883 flights
These figures cover 5,649 flights between September 2025 and August 2026. Beyond the headline rate, 13.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on ORD to SFO
The choice of carrier is not cosmetic here. United Airlines arrives on time 69.1% of the time; American Airlines manages 59.9%. Sample sizes sit next to every figure, because a two-point gap across 1,766 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 3,883 | 69.1% | 75 min | 0.82% | C+ |
| American Airlines | 1,766 | 59.9% | 73 min | 1.64% | D |
United leads American by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on ORD to SFO
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Chicago to San Francisco
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ORD → SFOChicago to San Francisco | United Airlines | 68.5% | 69.1% | 0.82% | 5am–8am, Tue | UA 1577 14:35 |
| 2. ORD → SFOChicago to San Francisco | American Airlines | 58.9% | 59.9% | 1.64% | 5am–8am, Sat | AA 1253 06:55 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against 9 points between the best and worst carrier.
- 5am–8am920 flights89.0%
- 8am–11am1,105 flights62.9%
- 11am–2pm676 flights67.7%
- 2pm–5pm1,201 flights67.2%
- 5pm–8pm1,016 flights53.0%
- 8pm–5am731 flights57.7%
Scale runs 45% to 95%.
The 5pm–8pm window is where this operation falls apart: 53.0% on time, against 89.0% 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 1,201 flights scheduled in it.
Explore
Filter ORD to SFO by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On ORD to SFO, the best departure window is 5am–8am at 89.0% on time and the worst is 5pm–8pm at 53.0%, a wide gap of 36.0 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am89.0%
- 8–11am62.9%
- 11am–2pm67.7%
- 2–5pm67.2%
- 5–8pm53.0%
- 8pm–5am57.7%
best all US flightsScale 45% to 95%.
Across the year
When delays peak on this route
This route's year swings by 28 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 49.9% on time, 28 points below September, the best at 77.6%. 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 559 flights.
Across the week, Tuesday is the strongest day at 75.7% on time and Monday the weakest at 60.7%, a spread of 15 points.
Delay causes
Why this route gets delayed
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 139,000 reported delay minutes.
- 42%Late-arriving aircraft
- 32%National Airspace System
- 23%Carrier
- 4%Extreme weather
- 0%Security
42% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 139,000 reported delay minutes here, that single category outweighs weather by 11 to one. The split is drawn from 139,359 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 89.0% on time here.
Cancellations sit at 1.08% against a national 1.89%, which is ordinary. Diversions add another 0.05%.
Connections and stage length
What a delay here actually costs
13.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 75.0% on time across 5,650 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 5,649 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.
Work out the risk of missing a connection in SFO after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 77.6% on time and June 49.9%, a swing of 28 points. If the dates move at all, move them out of June before you think about anything else. 5,585 completed flights over 12 months sit behind that.
Common questions
ORD to SFO questions
How often is ORD to SFO delayed?
About one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 33.8% of the 5,649 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on ORD to SFO?
United Airlines leads at 69.1% on time across 3,883 flights. American Airlines is at the other end on 59.9%, a gap of 9 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on ORD to SFO?
The 5am–8am departure window is the strongest at 89.0% on time. The 5pm–8pm window is the weakest at 53.0%, 36 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on ORD to SFO?
June is the weakest month at 49.9% on time, compared with 77.6% in September. Across the year that is 28 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SFO to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- San Francisco International (SFO) delay statistics
- United Airlines on ORD to SFO69.1%
- American Airlines on ORD to SFO59.9%
- ORD to LGA, a related route66.6%
- LAX to SFO, a related route60.1%
- ORD to BOS, a related route66.6%
- United Airlines on-time record69.1%
- American Airlines on-time record59.9%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. ORD to SFO and SFO to ORD are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.