Itineraries flown on 20+ days in the Jun 6 – Jul 31, 2026 schedule · each leg’s record Aug 2025 – Jul 2026

No clear winner: airlines and hours on this route all land within a few points of 77% on time.

Nonstops (seasonal or thin)


United	BUF	DEN	3h 35m	86%	0.0%	293	Flying now
Southwest	BUF	DEN	3h 35m	68%	0.4%	258	Flying now
Frontier	BUF	DEN	3h 41m	63%few flights	0.0%	35	Not flying now

Best connections, one ticket

Most reliable Quickest (80%+ on time)

Ranked by chance you reach Denver on time. Total trip = scheduled departure to arrival, layover included (Denver is 2 h behind Buffalo). Layovers up to 4 hours. Pick a connection for the details.


United Details →	BUF 07:00 → ORD 08:05UA 5820 · flown by SkyWest	2h 49m Chicago	ORD 10:54 → DEN 12:45UA 581	7h 45m	100%	94%
United Details →	BUF 06:15 → IAD 07:34UA 3668 · flown by Republic	2h 39m Dulles	IAD 10:13 → DEN 12:05UA 1865	7h 50m	95%	84%
Southwest Details →	BUF 06:05 → BWI 07:20WN 756	2h 20m Baltimore	BWI 09:40 → DEN 11:25WN 275	7h 20m	100%	84%
Delta Details →	BUF 06:00 → ATL 08:10DL 2664	3h 35m Atlanta	ATL 11:45 → DEN 12:59DL 706	8h 59m	99%	83%
American Details →	BUF 05:20 → PHL 06:46AA 5873 · flown by Piedmont	2h 49m Philadelphia	PHL 09:35 → DEN 11:56AA 3312	8h 36m	98%	83%
Delta Details →	BUF 09:03 → DTW 10:18DL 3639 · flown by SkyWest	2h 24m Detroit	DTW 12:42 → DEN 13:54DL 1648	6h 51m	98%	83%
United Details →	BUF 10:34 → IAD 11:50UA 3430 · flown by Republic	58m Dulles	IAD 12:48 → DEN 14:42UA 1587	6h 08m	88%	81%
American Details →	BUF 06:01 → CLT 08:01AA 1204	3h 29m Charlotte	CLT 11:30 → DEN 12:56AA 1758	8h 55m	98%	79%
Tight connection: often missed
United Details →	BUF 18:04 → ORD 19:03UA 2747	57m Chicago	ORD 20:00 → DEN 22:01UA 767	5h 57m	57%	39%
American Details →	BUF 16:46 → DFW 19:10AA 1615	1h 19m Dallas-Fort Worth	DFW 20:29 → DEN 21:32AA 577	6h 46m	70%	33%
Southwest Details →	BUF 19:50 → MDW 20:30WN 768	55m Chicago	MDW 21:25 → DEN 23:05WN 2770	5h 20m	47%	25%

Same layover, different day-part

How often the first flight arrives too late to connect (45 min minimum), for one-ticket layovers of 45–80 minutes.

Morning

DFW · 1h 16m · leaves 07:01 6%

DTW · 58m · leaves 06:29 11%

IAD · 58m · leaves 10:34 12%

Afternoon and evening

DFW · 1h 19m · leaves 16:46 30%

ORD · 57m · leaves 18:04 43%

MDW · 55m · leaves 19:50 53%

Delays build through the day, so an afternoon first leg eats the layover. A short connection is fine early in the morning and a gamble later on.

Mixing airlines

One ticketMiss it and the airline rebooks you; bags go through. 45 min is enough.

Separate ticketsMiss it and you buy a new ticket. Re-check bags, clear security again: we require 90 min.


Southwest WN 769 BUF 06:25 → TPA United UA 645 TPA 12:45 → DEN Connection details →	3h 35m	10h 22m	100%	92%
American AA 1195 BUF 06:00 → ORD United UA 581 ORD 10:54 → DEN Connection details →	3h 51m	8h 45m	97%	90%
JetBlue B6 85 BUF 07:35 → MCO United UA 1520 MCO 12:50 → DEN Connection details →	2h 35m	9h 16m	97%	89%

Rank all connections, any airlines →

Regional partners count as the airline that sells them: SkyWest flying Delta Connection is one Delta ticket.

How these are worked out. Makes the connection: share of the last year’s flights where the first flight arrived with at least 45 minutes to spare (90 on separate tickets). Arrives on time: first flight not cancelled × connection made × second flight not cancelled and arriving within 15 minutes. Not yet counted: the second flight also leaving late (which helps), gate-to-gate distance at the hub, and rebooking after a missed connection.

About this data: US DOT on-time records, Aug 2025 – Jul 2026, all US airlines; regional flights count under the airline that sells them. Schedules (which flights and connections exist, and their times) are as of Jun 6 – Jul 31, 2026; seasonal flights outside that window aren’t ranked. Rebuilt monthly. JSON