DECO 2000 Dive Planner

Enter your depth and time to see how long you can stay without deco stops, your group letter and when you can fly.

Results update as you type.

Quick examples

Load a full example, then change any value.

Planned depth (m)

The deepest point of the dive. It is rounded up to the next table depth.

Planned bottom time (min)

From leaving the surface to starting the ascent.

No-deco limit

Within limits

At 18 m you can stay 45 minutes without deco stops. Your 35-minute dive leaves you in group E.

Profile rounded to the table: 18 m · 35 min
No-deco limit: 45 min
Deco stops: No deco required
Post-dive group: E
Wait before flying: 16 hours

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This page is for education and reference. Real dive planning must rely on the current printed table and a dive computer; using the table requires training. The recreational limit is 30 metres, and a 5-minute safety stop at 3 metres is recommended on every dive.

About the DECO 2000 table

DECO 2000 is the dive table by Dr. Max Hahn used in CMAS and TSSF training. It is made for 0-700 m altitude and an ascent rate of 10 m/min.

The planner does the lookup you would do on the printed table. It finds the row for your depth and time, then reads the no-deco limit, any deco stops and your group letter. For a repetitive dive it first adds the residual nitrogen time.

With your numbers

Enter valid values to see the calculation worked through with your numbers.

Formula

Depth row: round up to the next table depth

drow = first table depth ≥ d

Time row: round up to the next time at that depth

trow = first table time ≥ t

Surface interval column

c = last threshold in your group's row that SI is longer than

Repetitive dive: add residual nitrogen, then find the time row

ttotal = t + tRN

Where

d, t: planned depth (m) and bottom time (min)
Table depths: 12 m to 42 m in 3 m steps; shallower dives use the 12 m row
SI: surface interval; an interval equal to a threshold has not passed it
tRN: residual nitrogen time from the residual table, row drow, column c
Past the last threshold: no residual nitrogen, plan it as a first dive
Deeper than 42 m or longer than the last time row: outside the table

How it's calculated

Depth and time are rounded up to the next values in the DECO 2000 table, so 16 m becomes 18 m and 30 min becomes 35 min.
Repetitive dives use the surface interval table for your group letter and the residual nitrogen table for the new depth.
The table is designed for 0-700 m altitude with an ascent rate of 10 m/min.

Good to know

Repetitive dives must always be planned shallower than the previous one.
If the dive went deeper or longer than planned, take your group letter from the real depth and time.
The surface interval runs from surfacing until you start the next dive.
Plan every dive of the day with the table. Don't switch to a dive computer's numbers halfway, because the two track nitrogen differently.

How to use the DECO 2000 planner

1
Single Dive: enter your planned depth and bottom time. The planner rounds both up to the next table values.
2
Repetitive Dive: pick the group letter from your previous dive and your surface interval. The planner adds residual nitrogen time to your new dive.
3
Read the no-deco limit, your group letter and the wait before flying. If stops appear, the dive is too long for recreational diving.

What the results mean

The no-deco limit is the longest bottom time at that depth without mandatory decompression stops.

The group letter describes how much extra nitrogen is left in your body after the dive. It sets how long to wait before the next dive or a flight.

Residual nitrogen time is added to the bottom time of your next dive, so a repetitive dive has less time before it needs stops.

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