Head to head

Atlas IIA 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 IIA: 6,580 kg

Atlas V 551: 18,850 kg

Side by side

9 comparable figures

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

Metric	Atlas IIA	Atlas V 551
Flights flown	23	23
Success rate	100%	100%
Payload to LEO (kg)	6,580	18,850
Payload to GTO (kg)	2,810	8,890
Liftoff thrust (kN)	2,479	12,269
Length (m)	47.54	59.7
Diameter (m)	3.04	3.8
Launch mass (t)	204	573
Stages	3	2

Atlas IIA

Flight record

100% success rate23 of 23 flown

1992peak 1996 · 4 flights2002

Maiden flight 1992-06-10. Retired.

Atlas V 551

Flight record

100% success rate23 of 23 flown

2006peak 2025 · 5 flights2026

Maiden flight 2006-01-19. Retired.

Atlas IIA is built by Lockheed Martin 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 IIA · 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.