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Calcimator

Dive Decompression Calculator

Estimate no-decompression limits, safety stop requirements, and dive risk levels. For educational planning only — always use certified dive tables or a dive computer.

Inputs

ft
min
min

Results

No-Deco Limit

56 min

Safety Stop Required1
Safety Stop Depth5 m
Safety Stop Duration3 min
Risk Level2
How to Use This Calculator
  1. Enter your planned dive depth in meters.
  2. Set your intended bottom time in minutes.
  3. Indicate whether this is a repetitive dive and enter your surface interval in minutes if so.
  4. Read No-Decompression Limit (NDL) in minutes — do not exceed this without decompression training and equipment.
  5. Check whether a safety stop is recommended and at what depth (usually 5 m for 3 minutes).
  6. Review the Dive Risk Level (Low/Moderate/High/Critical) to assess how conservatively you are diving.

How the result changes with Planned Depth

Planned DepthNo-Deco Limit
8.3219 min
2237 min
379 min
515 min

What each input means

Planned Depth
Maximum planned depth in meters. Recreational diving limits are typically 18m (Open Water) to 40m (Deep Diver).
Bottom Time
Total time from descent to beginning of final ascent, in minutes.
Repetitive Dive?
Whether you have dived within the last 12 hours.
Surface Interval
Time spent at the surface between dives, in minutes. Only relevant for repetitive dives. Longer intervals reduce residual nitrogen.

What each result means

No-Deco Limit
Maximum bottom time before mandatory decompression stops are required. Stay within this limit for recreational diving.
Safety Stop Required
1 = Yes (safety stop strongly recommended), 0 = No (still a good practice). Always do a safety stop on deeper dives.
Safety Stop Depth
Standard safety stop depth is 5 meters (15 feet).
Safety Stop Duration
Recommended safety stop duration. 3 minutes is standard; 5 minutes when approaching NDL limits.
Risk Level
1 = Low (<50% NDL), 2 = Moderate (50-75%), 3 = High (75-100%), 4 = Critical (exceeds NDL).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Planned Depth = 18, Bottom Time = 35, Repetitive Dive? = 0, Surface Interval = 60 = 4 input(s) provided
  2. Calculate No-Deco Limit
    56 = 56
  3. Calculate Safety Stop Required
    Safety Stop Required
    1 = 1
  4. Calculate Safety Stop Depth
    Safety Stop Depth
    5 = 5

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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