Carrier route record
UAMIA→SFO
United Airlines · Miami to San Francisco
- Flights
- 623
- Period
- July 2025 to June 2026
- Share of route
- 36%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on MIA 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, 5 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 623 flights, with a median arrival 4 minutes early.
The national on-time rate over the same period is 77.6%, so United on MIA to SFO runs 5 points behind the country as a whole. Across a thousand flights that is about 54 extra late arrivals.
Key figures
On time
72.2%
Arrivals under 15 minutes late, of 618 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
0.32%
National rate is 1.81%
Whole route
71.6%
Every carrier on MIA to SFO, 1,725 flights
These figures cover 623 flights between July 2025 and June 2026. Beyond the headline rate, 10.2% 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 MIA to SFO
United flew 623 of the 1,725 flights on MIA to SFO, about 36% of it. Its 72.2% on time is about level with the route as a whole at 71.6%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 72.2% to American at 71.2%.
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) | 623 | 72.2% | 71 min | 0.32% | C+ |
| American Airlines | 1,102 | 71.2% | 62 min | 0.91% | C+ |
Flight by flight
United flight numbers on MIA 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 29 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–8am113 flights89.4%
- 8am–11am170 flights83.4%
- 11am–2pm1 flights—
- 2pm–5pm1 flights—
- 5pm–8pm338 flights60.5%
- 8pm–5am—
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 60.5% on time, against 89.4% 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 5pm–8pm window is the busiest, with 338 flights scheduled in it.
Across the year
United on MIA to SFO through the year
October is the best month on the calendar at 88.2% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. January was the busiest month here, with 62 flights.
Across the week, Tuesday is the strongest day at 85.9% on time and Monday the weakest at 63.4%. 23 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 12,000 reported delay minutes.
- 39%National Airspace System
- 35%Carrier
- 23%Late-arriving aircraft
- 3%Extreme weather
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 4,265 of the 12,000 delay minutes reported here. The split is drawn from 12,188 reported delay minutes.
39% 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 4,748 minutes out of 12,000, against a national NAS share of 21%.
Cancellations are rare at 0.32%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
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. 10.2% 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 2,585 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 76.8% on time across 623 flights, 5 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 5 points of difference.
One caution: this is a thin sample. 623 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on MIA to SFO
Put together: treat all of this as provisional. 623 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 72.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 618 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to SFO, every carrier
- United on SFO to MIA, the return leg
- American Airlines on MIA to SFO71.2%
- United Airlines network-wide record
- Miami International (MIA) delay statistics
- San Francisco International (SFO) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- How often a connection fails at the major US hubs
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.