The Multi–Dive No–Decompression Limits (NDL) Calculator quickly shows your no–deco times for two consecutive dives by taking into account:
Dive 1: Enter depth and bottom time to get your ending pressure group and confirm your maximum NDL.
Surface Interval: Enter how long you plan to wait on the surface to see how much residual nitrogen “leaks off” and what starting group you’ll be in for Dive 2.
Dive 2: Enter your second-dive depth and bottom time to see both the fresh-dive NDL and the reduced repetitive-dive NDL based on your first dive’s residual nitrogen.
All in one tool—so you can instantly check that neither dive (nor the combination of both) exceeds no-decompression limits.
Dive 1
Depth (ft)
Bottom time (min)
NDL: 0h 56m
Surface Interval
SI (1h 0m)
Dive 2
Depth (ft)
Bottom time (min)
NDL: 0h 51m
Dive 1: 40 min @ 59ft → P
NDL: 0h 56m
SI: 1h 0m → E
Min SI: 2h 28m
Dive 2: 30 min @ 49ft → R
Adjusted NDL: 0h 51m
Start Group: E
Fresh NDL: 1h 12m
Adjusted NDL: 0h 51m
End Group: R
Fresh NDL is the no-decompression time from zero. Adjusted NDL accounts for residual nitrogen.
Important Warning: The calculators provided on this page are intended for reference purposes only. While we strive for accuracy, divers are strongly advised to verify the output of these calculators independently before use. Always double-check calculations and consider all safety factors relevant to your specific diving conditions and experience level. Diving without proper verification and planning can be dangerous. Dive safely and responsibly.
