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What this solves
Acute mountain sickness (AMS) is rare below 2,500 m but becomes common above 3,000 m, especially when sleep altitude climbs quickly. New Zealand has two scenarios where this matters: the Ruapehu crater-lake walks (2,500+ m) and Aoraki / Mt Cook day trips (below 3,000 m if you stay below the summit plateau). Most NZ trekkers are at low risk because they're doing day walks; trampers on the high Routeburn or Milford are at moderate risk above their sleep altitude.
This tool uses the Lake Louise AMS scoring model to give you an indicative risk. It does not replace medical advice or the discontinuation of a trip if you develop symptoms.
How to read the result
- Risk % is the chance of mild AMS (headache, nausea, fatigue) above 2,500 m sleep altitude.
- Ascent rate is calculated from starting altitude to sleep altitude divided by days.
- Acclimatisation score is a UI indicator. Below 300 m/day ascent is recommended for above 3,000 m.
Limitations
- AMS risk is individual; pre-acclimatisation, hydration and pace matter too.
- This is not a medical test. If you have headache, vomiting or confusion at altitude, descend.
- Risk above 3,500 m is significant; Aoraki summit is 3,724 m and requires guide.
FAQ
Q: Can AMS be fatal?
A: AMS itself is rarely fatal, but it can progress to HAPE or HACE (lung or brain oedema), which are. Descend immediately at any sign of confusion, breathlessness at rest, or loss of coordination.
A: AMS itself is rarely fatal, but it can progress to HAPE or HACE (lung or brain oedema), which are. Descend immediately at any sign of confusion, breathlessness at rest, or loss of coordination.
Q: What is the recommended acclimatisation rate?
A: Above 3,000 m sleep altitude, ascend no more than 300–500 m per day, with a rest day every 3–4 days.
A: Above 3,000 m sleep altitude, ascend no more than 300–500 m per day, with a rest day every 3–4 days.
Q: Is acetazolamide useful?
A: Yes, prescribed for rapid ascents. Not relevant for most NZ trips.
A: Yes, prescribed for rapid ascents. Not relevant for most NZ trips.
Sources
- Lake Louise Consensus AMS scoring (2018 update)
- DOC Mount Ruapehu
- New Zealand Alpine Club