Carrier route record

UAORD→BOI

United Airlines · Chicago to Boise

Flights: 245
Period: July 2025 to June 2026
Share of route: 22%
Carriers: 4

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.

United on ORD to BOI lands a B+, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 245 flights, with a median arrival 6 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate United on ORD to BOI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

78.2%

Arrivals under 15 minutes late, of 243 completed flights

Avg delay

59 min

Across delayed arrivals only, not all flights

Cancelled

0.41%

National rate is 1.81%

Whole route

69.1%

Every carrier on ORD to BOI, 1,108 flights

These figures cover 245 flights between July 2025 and June 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

United against every carrier on ORD to BOI

United flew 245 of the 1,108 flights on ORD to BOI, about 22% of it. Its 78.2% on time is 9 points better than the route as a whole, which runs 69.1%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 78.2% to SkyWest at 62.6%. Two 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.

On-time performance by carrier on ORD to BOI
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines (this page)thin sample	245	78.2%	59 min	0.41%	B+
American Airlinesthin sample	172	77.9%	67 min	0.00%	B+
Envoy Airthin sample	188	66.3%	49 min	0.00%	C+
SkyWest Airlines	503	62.6%	87 min	2.58%	D

Departure window

When United runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 245 flights.

5am–8am—
8am–11am194 flights82.3%
11am–2pm1 flights—
2pm–5pm33 flights75.8%
5pm–8pm—
8pm–5am17 flights—

Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.

The early departures do better, though not dramatically: 82.3% on time for the 8am–11am window against 75.8% for 2pm–5pm. Worth taking if the schedule allows, not worth an extra connection. The 8am–11am window is the busiest, with 194 flights scheduled in it.

Across the year

United on ORD to BOI through the year

Jul–Sep 202598 flights83.7%
Oct–Dec 202586 flights77.6%
Apr–Jun 202661 flights70.0%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 78.2% on time across 245 flights.

United on ORD to BOI did not run the same all year. Its best quarter was Jul–Sep 2025 at 83.7% on time and its weakest Apr–Jun 2026 at 70.0%, a swing of 14 points on roughly 82 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Thursday is the strongest day at 82.9% on time and Wednesday the weakest at 72.7%. 10 points is a smaller lever than departure hour, but it is free.

Delay causes

Why United runs late on this route

One category carries most of the weight here. Carrier accounts for 44% of the 3,134 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
44%
Late-arriving aircraft
41%
National Airspace System
14%
Extreme weather
0%

41% 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 3,134 reported delay minutes here, that single category outweighs weather by 41 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 3,134 reported delay minutes.

The largest share of delay minutes, 44%, 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 1,373 of the 3,134 delay minutes reported here.

Cancellations are rare at 0.41%, 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

7.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

The 1,437 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 77.1% on time across 244 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 245 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 ORD to BOI

Put together: treat all of this as provisional. 245 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 78.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 243 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures