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Altitude Acclimatisation Calculator

Work out altitude acclimatisation instantly with clear inputs, formula shown and shareable results.

About Altitude Acclimatisation Calculator

Above 3,000 m the accepted guidance is to raise sleeping altitude by no more than 300-500 m a day, with a rest day for every 1,000 m gained. What matters is sleeping altitude, not the high point reached — climbing high and sleeping low is the standard technique.

Formula

Acclimatisation

days = altitude gain / daily sleeping gain + rest days; recommended rest is one day per 1000 m

Worked example

With the default values below, Altitude Acclimatisation Calculator returns Days required of 9. Change any input above and every figure here is recalculated in your browser.

Inputs used

Starting altitude
2,800 m
Target altitude
5,400 m
Planned daily sleeping gain
400 m/day
Rest days planned
2 days

Results

Days required
9 days
Recommended maximum daily gain
300 m/day
Total altitude gain
2,600 m
Assessment
Ascent profile within accepted guidance

Step by step

  1. 1Values used
  2. 2Acclimatisation
  3. 3Days required= 9 days
  4. 4Recommended maximum daily gain= 300 m/day
  5. 5Total altitude gain= 2,600 m
  6. 6Assessment= Ascent profile within accepted guidance

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does sleeping altitude matter more?

Because acclimatisation happens over hours of sustained exposure. A brief visit to a higher point stimulates adaptation without the overnight stress.

What are the warning signs?

Headache, nausea, fatigue and poor sleep indicate acute mountain sickness. The only reliable treatment is to descend.

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