Head to head

Atlas V 551 vs Soyuz U

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 U: 6,900 kg

Side by side

7 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 U
Flights flown	23	714
Success rate	100%	97.2%
Payload to LEO (kg)	18,850	6,900
Length (m)	59.7	51.1
Diameter (m)	3.8	2.95
Launch mass (t)	573	313
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 U

Flight record

97.2% success rate694 of 714 flown · 20 failed

1973peak 1979 · 47 flights2017

Maiden flight 1973-05-18. Retired.

Atlas V 551 is built by United Launch Alliance of the United States (company profile on Space Index).Soyuz U is built by Russian Federal Space Agency (ROSCOSMOS) of Russia.

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

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