The current Opel Astra is 4,374 mm long, 1,860 mm wide and 1,470 mm tall, on a 2,675 mm wheelbase. It has grown 32 cm longer since the 1991 Astra.
| Years | Length | Width | Height | Wheelbase | Boot capacity | Turning circle |
|---|---|---|---|---|---|---|
| 1991–1998 | 4,051 | 1,688 | 1,410 | 2,517 | 360 | 10.5 |
| 1998–2004 | 4,110 | 1,709 | 1,425 | 2,606 | 370 | 10.1 |
| 2004–2009 | 4,249 | 1,753 | 1,460 | 2,614 | 347 | 10.5 |
| 2009–2012 | 4,419 | 1,814 | 1,510 | 2,685 | 370 | 11.5 |
| 2012–2017 | 4,429 | 1,820 | 1,504 | 2,687 | 372 | 11.5 |
| 2015–2021 | 4,370 | 1,809 | 1,485 | 2,662 | 370 | 11.1 |
| 2021–2026 | 4,374 | 1,860 | 1,441 | 2,675 | 402 | 10.5 |
| 2026–presentCurrent | 4,374 | 1,860 | 1,470 | 2,675 | 361 | 11.1 |
Exterior figures are manufacturer specifications for the Astra, averaged per generation across its variants and shown for the most common body style. Generations with the same size are merged. Boot capacity is the seats-up figure where the manufacturer quotes one.