Head to head

Atlas V 401 vs Atlas V 551

Two vehicles in the same payload class. Every figure below comes from the same two sources for both rockets, and a row appears only when both publish the input.

Payload to low Earth orbit

Relative

Atlas V 401: 9,050 kg

Atlas V 551: 18,850 kg

Side by side

11 comparable figures

The highlighted value wins the row. Rows where neither direction is better, like length or stage count, highlight nothing.

Metric	Atlas V 401	Atlas V 551
Flights flown	41	23
Success rate	100%	100%
Payload to LEO (kg)	9,050	18,850
Payload to GTO (kg)	4,950	8,890
Launch cost	$115M	$153M
Cost per kg to LEO	$12,707	$8,117
Liftoff thrust (kN)	3,827	12,269
Length (m)	58.3	59.7
Diameter (m)	3.8	3.8
Launch mass (t)	590	573
Stages	2	2

Atlas V 401

Flight record

100% success rate41 of 41 flown

2002peak 2014 · 7 flights2022

Maiden flight 2002-08-21. Retired.

Atlas V 551

Flight record

100% success rate23 of 23 flown

2006peak 2025 · 5 flights2026

Maiden flight 2006-01-19. Retired.

Atlas V 401 is built by United Launch Alliance of the United States (company profile on Space Index).Atlas V 551 is built by United Launch Alliance of the United States (company profile on Space Index).

Full specifications and the complete launch history for each: Atlas V 401 · Atlas V 551.

Specifications from Launch Library 2 by The Space Devs, launch records from Space Index. Derived figures are computed here; see sources and method.