A close look at two backpacks buyers cross-shop. They score within a hair of each other, so it comes down to the details below.
| Granite Gear Perimeter 50 | Arc'teryx Alpha AR 55 | |
|---|---|---|
| GearScore | 65✓ | 64 |
| Capacity | 50 L | 55 L |
| Weight | 3 lb 2 oz | 2 lb 14 oz✓ |
| Rated load | 40 lb | n/s |
| Fabric denier | 100 D | 315 D✓ |
| Price | $250✓ | $250 |
| Type | Backpacking | Backpacking |
| Frame | Internal | Internal |
Highlighted cells mark the better spec: Perimeter 50 in blue, Alpha AR 55 in amber. A blank spec is never counted as a win. Capacity is shown for context and is not scored, since more volume is a sizing choice rather than better. GearScore is the overall rating (0 to 100); re-weight it on the full backpack comparison. Prices are current MSRP.
Put the Granite Gear Perimeter 50 next to the Arc'teryx Alpha AR 55 and the trade-offs are clear. They are close enough that this really is about which handful of specs you weight most.
The Perimeter 50 is a little cheaper. The Alpha AR 55 is 4 oz lighter and tougher fabric (315D vs 100D). Their GearScores land within a couple of points (65 vs 64), so neither runs away with it.
Pick the Perimeter 50 if you care most about price, which makes it the better call for getting the most for your money. Pick the Alpha AR 55 if low weight and durability matter more to you, or you are focused on counting grams on long miles.
The Arc'teryx Alpha AR 55. It is 4 oz lighter than the Perimeter 50.
The Granite Gear Perimeter 50. It is a little cheaper than the Alpha AR 55.
They are nearly tied at 65 and 64 on the default algorithm, so re-weight the score to your own priorities to break the tie.
It depends on your priorities. Go with the Perimeter 50 for price, or the Alpha AR 55 for low weight. The spec table above shows exactly where each wins.