Carrier route record
UASFO→MIA
United Airlines · San Francisco to Miami
- Flights
- 604
- Period
- September 2025 to August 2026
- Share of route
- 35%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on SFO to MIA lands a B+, level with the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about 40 minutes on average. That rests on 604 flights, with a median arrival 1 minute early.
The US average over the same twelve months is 77.3%, so there is little to separate United on SFO to MIA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.9%
Arrivals under 15 minutes late, of 601 completed flights
Avg delay
39 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
Whole route
76.5%
Every carrier on SFO to MIA, 1,741 flights
These figures cover 604 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
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Carrier by carrier
United against every carrier on SFO to MIA
United flew 604 of the 1,741 flights on SFO to MIA, about 35% of it. Its 77.9% on time is about level with the route as a whole at 76.5%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 77.9% to American at 75.8%.
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) | 604 | 77.9% | 39 min | 0.00% | B+ |
| American Airlines | 1,137 | 75.8% | 79 min | 0.88% | B+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 16 points, against half a point between the best and worst carrier.
- 5am–8am29 flights—
- 8am–11am310 flights69.4%
- 11am–2pm16 flights—
- 2pm–5pm—
- 5pm–8pm—
- 8pm–5am249 flights85.1%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
The overnight block holds up unusually well at 85.1% on time across 249 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8am–11am window is the busiest, with 310 flights scheduled in it.
Across the year
United on SFO to MIA through the year
August is the worst month at 48.7% on time, 46 points below October, the best at 94.3%. 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. January was the busiest month here, with 62 flights.
Across the week, Tuesday is the strongest day at 82.4% on time and Saturday the weakest at 72.5%, a spread of 10 points.
Arrival by arrival
How late United on SFO to MIA runs when it is late
Most of the lateness is short. 69 of the 133 late arrivals were under half an hour behind, and 19 reached an hour or more.
- 15+ min early125 flights20.8%
- Within 15 min343 flights57.1%
- 15–29 min late69 flights11.5%
- 30–59 min late45 flights7.5%
- 1–2 hours late13 flights2.2%
- 2+ hours late6 flights1.0%
Scale runs 0% to 100%.
Share of 601 completed flights by arrival against schedule.
A late pushback is often recovered here: of 89 departures that left 15 minutes late or more, 35 still arrived on time. In the other direction, 79 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at MIA.
The worst days
Worst days for United on SFO to MIA
The latest arrival of the period was on 16 March 2026, 3 hours 16 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 16 March 2026 | 3 hours 16 minutes | Late-arriving aircraft |
| 15 February 2026 | 2 hours 27 minutes | Late-arriving aircraft |
| 24 April 2026 | 2 hours 24 minutes | Carrier |
| 21 December 2025 | 2 hours 5 minutes | Late-arriving aircraft |
| 27 December 2025 | 2 hours 4 minutes | National Airspace System |
Delay causes
Why United runs late on this route
National Airspace System accounts for 53% of the 5,184 delay minutes carriers reported here, and the remaining four split what is left.
- 53%National Airspace System
- 26%Late-arriving aircraft
- 21%Carrier
53% 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 2,749 minutes out of 5,184, against a national NAS share of 21%. The split is drawn from 5,184 reported delay minutes.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 3.2% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 73.7% on time across 603 flights, 4 points below 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 4 points of difference.
One caution: this is a thin sample. 604 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 SFO to MIA
Put together: treat all of this as provisional. 604 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 77.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 601 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to MIA, every carrier
- United on MIA to SFO, the return leg
- American Airlines on SFO to MIA75.8%
- United Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Miami International (MIA) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
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.