Head to head

Soyuz 2.1a 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

Soyuz 2.1a: 7,020 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	Soyuz 2.1a	Soyuz U
Flights flown	58	714
Success rate	98.3%	97.2%
Payload to LEO (kg)	7,020	6,900
Length (m)	46.3	51.1
Diameter (m)	2.95	2.95
Launch mass (t)	312	313
Stages	3	3

Soyuz 2.1a

Flight record

98.3% success rate57 of 58 flown · 1 failed

2004peak 2023 · 7 flights2026

Maiden flight 2004-11-04. Still flying.

Soyuz U

Flight record

97.2% success rate694 of 714 flown · 20 failed

1973peak 1979 · 47 flights2017

Maiden flight 1973-05-18. Retired.

Soyuz 2.1a is built by Progress Rocket Space Center of Russia.Soyuz U is built by Russian Federal Space Agency (ROSCOSMOS) of Russia.

Full specifications and the complete launch history for each: Soyuz 2.1a · 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.