Glock 20 vs 21 Size Comparison
The Glock 20 and Glock 21 are the same size outside: Glock lists identical length, height and width. They differ in caliber: 10mm Auto against .45 ACP. Both drawn to scale from Glock's published dimensions.
Glock 20 vs 21 side by side
Glock A
Glock B
Side profile
From behind
- Slide width
- 1.12 in1.12 in
- Same
- Overall width, with controls
- 1.38 in1.38 in
- Same
Tap the drawing to flip between the Glock 20, the Glock 21 and both.
Photos: Glock 17 Gen5 photo by Tony Webster, cut out by LeoPavouk (CC BY 2.0); Glock 43X photo by Kolomaznik (CC BY 4.0); Glock 17 Gen4 photo by Steve Dock, UK Ministry of Defence (OGL v1.0) Contains public sector information licensed under the Open Government Licence v1.0. Cut out and reshaped to each model's published size by GunPartPicker.
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Quick answer
The Glock 20 and Glock 21 are the same size outside: Glock lists identical length, height and width. They differ in caliber: 10mm Auto against .45 ACP.
- Glock 20: 8.07 in long, 5.51 in tall, 1.38 in wide, 4.61 in barrel. Glock 21: 8.07 in long, 5.51 in tall, 1.38 in wide, 4.61 in barrel.
One square is one inch. Real Glock photos sized to Glock's published dimensions, checked September 27, 2026.
Is the Glock 20 or 21 bigger?
Neither. The Glock 20 and Glock 21 take up the same space: Glock lists the same outside dimensions for both.
Glock 20 vs 21 dimensions
| Dimension | Glock 20 | Glock 21 | B vs A |
|---|---|---|---|
| Overall length | 8.07 in205 mm | 8.07 in205 mm | Same |
| Slide length | 7.52 in191 mm | 7.52 in191 mm | Same |
| Barrel length | 4.61 in117 mm | 4.61 in117 mm | Same |
| Height with magazine | 5.51 in140 mm | 5.51 in140 mm | Same |
| Overall width, with controls | 1.38 in35 mm | 1.38 in35 mm | Same |
| Slide width | 1.12 in28 mm | 1.12 in28 mm | Same |
| Trigger reach | 2.85 in72 mm | 2.85 in72 mm | Same |
| Weight, empty magazine | 28.4 oz805 g | 29.1 oz825 g | +0.7 oz20 g |
| Capacity, standard magazine | 15 rounds | 13 rounds | −2 |
| Caliber | 10mm Auto | .45 ACP | Different |
| Glock catalog | Current model | Current model |
Glock 20 vs 21 grip length
The Glock 20 and Glock 21 are the same height with a magazine in, 5.51 in (140 mm), and the trigger reach is the same, 2.85 in (72 mm).
Glock 20 vs 21 barrel and slide length
Both carry a 4.61 in (117 mm) barrel. The slides are the same length, 7.52 in (191 mm).
Will a Glock 21 fit a Glock 20 holster?
Often yes. The Glock 21 has the same slide length and width as the Glock 20, so a holster that leaves the grip free usually takes both. Holster makers mold for exact models, so check the maker's fit list before you buy.
Is the Glock 21 compact or subcompact?
Glock puts the Glock 21 in its full size large frame class and the Glock 20 in its full size large frame class. Here is every current Glock at the same scale.
Subcompact slimline
Subcompact
Compact
Full size
Every card is to the same scale, lined up at the slide rear. Tap one to compare it or look at it alone.
Where can I buy a Glock 20 or 21 today?
Glock 20 in stock
In stock now. One listing per model family.
Glock 21 in stock
In stock now. One listing per model family.
More Glock 20 and 21 comparisons
Frequently Asked Questions
Are the Glock 20 and Glock 21 the same size?
Neither. The Glock 20 and Glock 21 take up the same space: Glock lists the same outside dimensions for both.
Which is lighter, the Glock 20 or the Glock 21?
The Glock 20, by 0.7 oz (20 g) with an empty magazine: 28.4 oz (805 g) against 29.1 oz (825 g) for the Glock 21.
Which holds more rounds, the Glock 20 or the Glock 21?
The Glock 20: 15 rounds in a standard magazine against 13 for the Glock 21, as Glock's spec pages list them.
Where do these Glock 20 and Glock 21 numbers come from?
From Glock's own US spec pages, checked September 27, 2026. Both guns are shown at one scale, as real Glock photos reshaped to those numbers.
Cite this tool: GunPartPicker, “Glock 20 vs 21 Size Comparison”, https://gunpartpicker.net/tools/glock-size-comparison/glock-20-vs-21. Data from the GunPartPicker catalog and real community builds, prices checked November 11, 2026. Free to cite with attribution.
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