Free tool
How fast does your trek climb?
Altitude is the real risk on a high Himalayan trek — and it comes down to how fast you gain sleeping altitude. This checks any itinerary, night by night, against the Wilderness Medical Society ascent-rate guideline. Four treks are built in: Annapurna and Everest Base Camp from our measured GPS tracks, plus the Annapurna Circuit (over Thorong La, 5,416 m) and Mardi Himal from their standard sourced itineraries.
Planning information, not medical advice — it can’t predict altitude sickness. Read the altitude guide and know the symptoms before you go.
Your nightly sleep altitudes, in order (metres):
Altitude is the one thing fitness alone can’t fix.
The altitude guide covers acclimatisation, the golden rules and the AMS/HACE/HAPE symptoms. The Trek-Ready Program builds altitude readiness into your 12-week prep.
The ascent-rate rule this uses
Once you are sleeping above 3,000 m, the widely-cited guideline is:
- Increase your sleeping altitude by no more than ~500 m per day.
- Take a rest / acclimatisation day every 3–4 days, or roughly every 1,000 m of ascent.
- “Climb high, sleep low” is fine and helps — it’s the height you sleep at that drives acclimatisation.
This tool flags each night’s gain in sleeping altitude against that 500 m figure (amber from 400 m, red over 500 m) and checks for a rest day roughly every 1,000 m. Some clinicians advise a more conservative 300 m per day — treat green as “within the common guideline”, not “guaranteed safe”. Individual susceptibility to altitude illness varies enormously and isn’t captured by any rule.
Source: Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2019 Update (Luks AM, Auerbach PS, Freer L, et al., Wilderness & Environmental Medicine 2019;30(4S):S3–S18) — the same source as our altitude guide. Trek sleep altitudes are measured off our own GPS tracks — see how we measure.
Common questions
What is a safe ascent rate for high-altitude trekking?
The Wilderness Medical Society guideline is that once you are sleeping above 3,000 m, you should increase your sleeping elevation by no more than about 500 m per day, and take a rest (acclimatisation) day every 3–4 days or roughly every 1,000 m of ascent. It is the sleeping altitude that matters — climbing high and sleeping low is fine and helps.
Is the Annapurna Base Camp trek too fast to acclimatise?
By the guideline, its ascent is aggressive. On our measured itinerary you climb from Deurali (3,152 m) to Annapurna Base Camp (4,131 m) — a 979 m sleeping-elevation gain in a single night, roughly double the 500 m guideline, with no rest day. ABC prioritises reaching the sanctuary over gradual acclimatisation, so ascend conservatively, watch for symptoms, and consider adding a night if you can.
Is the Annapurna Circuit’s ascent to Thorong La safe?
The standard Annapurna Circuit is built for acclimatisation — it climbs gradually and includes the essential Manang rest day at ~3,540 m. Even so, by the 500 m guideline a couple of nights run over, such as the climbs to Upper Pisang and Yak Kharka (4,050 m). You cross Thorong La at 5,416 m on a single big day but sleep far lower on either side (Thorong Phedi ~4,540 m, then down to Muktinath ~3,760 m) — the right pattern of climb high, sleep low. Never skip the Manang day, and descend if symptoms worsen. These are sourced standard-itinerary altitudes, not measured by us.
How many acclimatisation days does Everest Base Camp need?
The Namche Bazaar acclimatisation day (around 3,440 m) is essential and built into almost every itinerary. Even so, the standard 10-day plan still exceeds the 500 m guideline on a couple of nights — notably Dingboche (4,325 m) to Lobuche (4,925 m), a 600 m gain — which is why many trekkers add a second acclimatisation day around Dingboche.
What altitude do you sleep at on the Everest and Annapurna Base Camp treks?
On Everest Base Camp the highest you sleep is 5,160 m at Gorakshep (measured). On Annapurna Base Camp the highest you sleep is 4,131 m, at Base Camp itself — lower than the entire upper half of the EBC trek. Both figures are off our GPS tracks.
Does this altitude planner give medical advice?
No. It compares your itinerary’s sleeping-altitude gains against a published ascent-rate guideline as planning information. It cannot predict altitude illness, which varies hugely between people. Read the altitude guide, know the symptoms of AMS, HACE and HAPE, and consult a doctor before a high-altitude trek.