What is the success rate on Denali's West Buttress route with a summit permit?

Roughly half. Denali's overall success rate runs 50 to 55 percent across the approximately 1,200 climbers who attempt it each year, and the West Buttress, which carries about 90 percent of all traffic, sits right at that average. The two factors that turn climbers back are weather and altitude, not technical difficulty.

Budget 17 to 21 days for the West Buttress, and treat the long end as realistic rather than padded. The route climbs about 13,500 feet from Kahiltna Base Camp at 7,200 feet through a chain of camps (Ski Hill at 7,800, Motorcycle Hill at 9,700, Basin Camp at 11,000, the 14,200-foot camp, and High Camp at 17,200), with acclimatization carries built into that schedule. Storms with sustained 100 mph winds can pin teams in camp for days, and teams that arrive without weather margin in their itinerary are the ones that go home short.

Conditions are the other filter. This is the coldest of the Seven Summits, with temperatures regularly reaching minus 40, and the climbing is self-supported: you haul everything on sleds, melt snow for all water, and use Clean Mountain Cans for waste. Crevasse hazard runs the length of the lower glacier, worse late season as snow bridges weaken, which is part of why May and early June are the preferred launch weeks.