Buoyancy & conditions / Calculator 08
Altitude Diving Calculator
Explore how lower surface pressure changes a true water depth's theoretical sea-level equivalent.
The numbers / explained
Ready when you are.
Start with the example or enter your own numbers, then calculate.
Every result includes units. All calculations run in your browser.
01 / The calculation
How it works
Standard-atmosphere surface pressure ratio = (1 − 6.8756 × 10⁻⁶ × altitude in feet)^5.255876. Equivalent sea-level saltwater depth = true depth × density ratio ÷ pressure ratio; fresh water uses density ratio 1/1.027. A reference 15-ft (5-m) stop scales by pressure ratio ÷ density ratio.
Reference: DAN: Altitude and decompression sickness02 / Before you use it
Keep in mind
Educational cross-correction only, limited here to 10,000 ft (3,048 m). Weather, acclimatization, previous dives, ascent to higher elevations and gauge behavior are not modeled. Enter true water depth, not an uncorrected sea-level gauge reading. Use altitude-specific training and an appropriate computer or approved tables for actual diving.