Route reliability record
MIA→SFO
Miami to San Francisco
- Flights
- 1,725
- Period
- July 2025 to June 2026
- Distance
- 2,585 mi
- Carriers
- 2
This route sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,725 MIA to SFO flights, of which United Airlines flew 623 at 72.2% on time.
Best time to fly MIA to SFO: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 89.2% of the time and Tuesday flights 81.8%, against 71.6% for the route overall.
The national on-time rate over the same period is 77.6%, so this route runs 6 points behind the country as a whole. Across a thousand flights that is about 60 extra late arrivals.
Key figures
On time
71.6%
Arrivals under 15 minutes late, of 1,709 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.70%
National rate is 1.81%
Best carrier
United
72.2% on time across 623 flights
These figures cover 1,725 flights between July 2025 and June 2026. Beyond the headline rate, 9.6% 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
Which airline is most reliable on MIA to SFO
The two carriers here are closely matched: about a point separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 623 | 72.2% | 71 min | 0.32% | C+ |
| American Airlines | 1,102 | 71.2% | 62 min | 0.91% | C+ |
No carrier stands out. United tops the table at 72.2%, about a point clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on MIA 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.
Best ways to make this trip
The most reliable ways to fly Miami to San Francisco
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. FLL → SFOFort Lauderdale to San Francisco | United Airlines | 83.5% | 83.8% | 0.41% | 8am–11am, Wed | — |
| 2. FLL → SFOFort Lauderdale to San Francisco | JetBlue Airways | 76.3% | 76.7% | 0.52% | 5am–8am, Wed | B6 277 20:00 |
| 3. MIA → SFOMiami to San Francisco | United Airlines | 72.0% | 72.2% | 0.32% | 5am–8am, Tue | UA 2423 18:35 |
| 4. MIA → SFOMiami to San Francisco | American Airlines | 70.6% | 71.2% | 0.91% | 5am–8am, Tue | — |
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 28 points, against about a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am289 flights89.2%
- 8am–11am355 flights83.9%
- 11am–2pm1 flights—
- 2pm–5pm115 flights63.5%
- 5pm–8pm750 flights61.3%
- 8pm–5am215 flights67.1%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 61.3% on time, against 89.2% 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 750 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 30 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.
Delays peak in May, when the on-time rate falls to 56.1%. March is the strongest month at 86.1%. Moving a flexible trip across that boundary buys 30 points. June was the busiest month here, with 174 flights.
Across the week, Tuesday is the strongest day at 81.8% on time and Monday the weakest at 65.3%. 17 points is a smaller lever than departure hour, but it is free.
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 32,000 reported delay minutes.
- 35%National Airspace System
- 33%Late-arriving aircraft
- 28%Carrier
- 4%Extreme weather
- 0%Security
35% 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 11,000 minutes out of 32,000, against a national NAS share of 21%. The split is drawn from 31,526 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 89.2% on time here.
Cancellations are rare at 0.70%, 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 actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.6% 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 77.4% on time across 1,725 flights, 6 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 6 points of difference.
The sample behind these figures is 1,725 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. March runs 86.1% on time and May 56.1%, a swing of 30 points. If the dates move at all, move them out of May before you think about anything else. 1,709 completed flights over 12 months sit behind that.
Common questions
MIA to SFO questions
How often is MIA to SFO delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 28.4% of the 1,725 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on MIA to SFO?
United Airlines leads at 72.2% on time across 623 flights. American Airlines is at the other end on 71.2%, a gap of about a point. 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 MIA to SFO?
The 5am–8am departure window is the strongest at 89.2% on time. The 5pm–8pm window is the weakest at 61.3%, 28 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 May delays on MIA to SFO?
May is the weakest month at 56.1% on time, compared with 86.1% in March. Across the year that is 30 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 MIA — the return legseparate record
- Miami International (MIA) delay statistics
- San Francisco International (SFO) delay statistics
- United Airlines on MIA to SFO72.2%
- American Airlines on MIA to SFO71.2%
- MIA to ATL, a related route73.7%
- LAX to SFO, a related route64.8%
- MIA to LGA, a related route68.0%
- United Airlines on-time record72.2%
- American Airlines on-time record71.2%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. MIA to SFO and SFO to MIA 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.