How the numbers are made
Shikhar is a decision-support tool built on published physiology and mountain-medicine consensus — not opinion, and not a black box. Here is exactly what runs under the screens.
The physiology
Barometric pressure at altitude comes from West’s equation; inspired oxygen from the alveolar gas equation with a modelled hypoxic ventilatory response; estimated SpO₂ from the Severinghaus dissociation curve. Values are conservative — for a healthy lowland adult on first exposure.
The AMS engine
Each night’s risk is scored from absolute sleeping altitude, the sleeping gain from the night before, acclimatisation debt since the last rest day, fast arrivals and big summit pushes — encoding the WMS/CDC ascent-rate rules. The optimiser only ever applies those same rules in reverse.
Honest limits
Individual susceptibility varies enormously; this is population-level guidance, not a diagnosis. Shikhar never prescribes medication. It is decision support, not a doctor or a rescue service — always carry insurance and the humility to turn around.
Sources
Reviewed against published mountain-medicine consensus. Found something we should refine? Tell us.