Head to head

Soyuz 2.1a 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

Soyuz 2.1a: 7,020 kg

Soyuz 2.1b: 8,200 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	Soyuz 2.1a	Soyuz 2.1b
Flights flown	58	25
Success rate	98.3%	100%
Payload to LEO (kg)	7,020	8,200
Payload to GTO (kg)	2,810	3,250
Payload to SSO (kg)	4,230	4,900
Launch cost	$80M	$80M
Cost per kg to LEO	$11,396	$9,756
Length (m)	46.3	46.3
Diameter (m)	2.95	2.95
Launch mass (t)	312	312
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 2.1b

Flight record

100% success rate25 of 25 flown

2008peak 2021 · 4 flights2026

Maiden flight 2008-07-26. Still flying.

Soyuz 2.1a is built by Progress Rocket Space Center of Russia.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: Soyuz 2.1a · 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.