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Altitude Adjustment Calculator

Plan acclimatisation for a high-altitude ascent.

About Altitude Adjustment Calculator

Acclimatisation is governed by sleeping altitude rather than the highest point reached, so gaining 400 metres of sleeping altitude a day is the accepted guidance above 3,000 metres. Rest days consolidate the adaptation. Altitude sickness is a function of ascent rate rather than fitness, which is why fit climbers who move fast are at higher risk than slower, less fit ones.

Formula

Altitude Adjustment

Days = altitude to gain ÷ safe daily gain, plus a rest day at the chosen interval

safe daily gain
About 300 to 500 m of sleeping altitude above 3,000 m
climb high sleep low
Sleeping altitude matters more than the day’s high point

Worked example

With the default values below, Altitude Adjustment Calculator returns Acclimatisation Days Needed of 8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Target altitudeaccepts 0–9,000 m
4,200 m
Current altitudeaccepts 0–9,000 m
1,800 m
Maximum daily sleeping altitude gainaccepts 50–1,500 m
400 m
Rest day every so many daysaccepts 1–14 days
3 days
Previous high-altitude experienceone of None, Some, Extensive
Some

Results

Acclimatisation Days Needed
8 days
Altitude to Gain
2,400 m
Ascent Days
6 days
Rest Days
2 days
Altitude Sickness Risk
Low for this altitude — ascent rate follows accepted guidance

Step by step

  1. 1Values used
  2. 2Altitude Adjustment
  3. 3Acclimatisation Days Needed= 8 days
  4. 4Altitude to Gain= 2,400 m
  5. 5Ascent Days= 6 days
  6. 6Rest Days= 2 days
  7. 7Altitude Sickness Risk= Low for this altitude — ascent rate follows accepted guidance

Assumptions and limits

  • The result is derived only from the 5 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

How is Altitude Adjustment calculated?

Days = altitude to gain ÷ safe daily gain, plus a rest day at the chosen interval Acclimatisation is governed by sleeping altitude rather than the highest point reached, so gaining 400 metres of sleeping altitude a day is the accepted guidance above 3,000 metres. Rest days consolidate the adaptation.

Why does Altitude Adjustment matter?

Altitude sickness is a function of ascent rate rather than fitness, which is why fit climbers who move fast are at higher risk than slower, less fit ones.

What values do I need to enter?

This calculator takes 5 inputs: Target altitude, Current altitude, Maximum daily sleeping altitude gain, Rest day every so many days, Previous high-altitude experience. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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