[zrezzed]

Sure. Most of my experience is in California, but I've found the grading differences from region to region to be just large as from out of state or international.

I climb 5.11c+ comfortably in the gym. I can barely lead a short Yosemite 5.8 outdoors; it's terrifyingly more difficult. That's a bit on the high side of a delta, but still typical.

I would say the difference is 75%+ in the scales simply not being the same. For the same grade, the holds would be far smaller, positions much more technical, often far more sustained, etc. The other ~25% is the environment is much more challenging, even with perfect weather at sea level: route finding is harder, you have to manage gear, leading is scary, etc.

I've done a few high Sierra climbs. Grades there are little softer, and my limit is probably ~5.7

[bryananderson]

For what it’s worth, there is also a wide variance in grading between different indoor gyms and different outdoor climbing areas.

Yosemite grades are notoriously hard; the most popular gym chain in California (which I love!) grades are notoriously soft. YMMV at other gyms and at other outdoor crags.

At the end of the day it’s a subjective guide, I wouldn’t get too hung up on the numbers.

[VHRanger]

There's also the factor for people who climb inside a lot that they have very inefficient movements outside.

Because the grips aren't as obvious, a lot of effort is wasted looking for placements that would be immediate indoors.

[scoot]

"Grips"? I guess you mean "holds" (indoors). "Placements"? That's where you place gear, not your fingers, and you don't place gear in climbing gyms. I appreciate your enthusiasm, but pretending to have knowledge of something you know nothing about is a real problem on HN (and the internet in general). Best to say nothing than make a fool of yourself – something I'm still learning.

[Cpoll]

Alternatively, they speak a different language with different terminology and are translating. I know a few climbing terms in French and they're quite different.

What would be helpful is commenting on whether their assertion is correct or not w.r.t efficiency.

[snowwrestler]

It’s definitely true. The high visibility of holds in the gym makes it easy to move quickly, even your first time up it, which saves a lot of energy.

Outside, the good and bad holds are probably the same color, and may be oriented in weird ways that require some feeling around to find the best way to grip them or stand on them.

Over time, climbers outside can learn to read the rock and make very good guesses about how to reach or step for the next usable hold. But it takes time to learn, and is somewhat location-specific because of the widely varying geology of climbable rock.

[InitialLastName]

> Best to say nothing than make a fool of yourself – something I'm still learning.

I love seeing people plumb the depths of irony this way.

[sulam]

This difference is mostly about the rock and the technique. Granite is very different from limestone and Yosemite cracks are very very different from a gym. (And Tuolumne domes are yet another thing.) If you spent a summer climbing in Yosemite you'd get comfortable with the style and the grades and they'd make more sense to you.

Conversely if you took a trip to Smith Rock or Owens River Gorge you'd get a much closer correspondence between gym ratings and rock ratings.