Head to head

Atlas V 551 vs Soyuz 2.1b

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 551: 18,850 kg

Soyuz 2.1b: 8,200 kg

Side by side

10 comparable figures

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

Metric	Atlas V 551	Soyuz 2.1b
Flights flown	23	25
Success rate	100%	100%
Payload to LEO (kg)	18,850	8,200
Payload to GTO (kg)	8,890	3,250
Launch cost	$153M	$80M
Cost per kg to LEO	$8,117	$9,756
Length (m)	59.7	46.3
Diameter (m)	3.8	2.95
Launch mass (t)	573	312
Stages	2	3

Atlas V 551

Flight record

100% success rate23 of 23 flown

2006peak 2025 · 5 flights2026

Maiden flight 2006-01-19. Retired.

Soyuz 2.1b

Flight record

100% success rate25 of 25 flown

2008peak 2021 · 4 flights2026

Maiden flight 2008-07-26. Still flying.

Atlas V 551 is built by United Launch Alliance of the United States (company profile on Space Index).Soyuz 2.1b is built by Progress Rocket Space Center of Russia (company profile on Space Index).

Full specifications and the complete launch history for each: Atlas V 551 · Soyuz 2.1b.

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