MN90 vs MT2019
Key differences between recreational and professional dive tables
ℹ️ Comparison for informational purposes. See the full tables: MN90 | MT2019.
Two tables, two worlds
MN90 tables (French Navy 1990) and MT2019 tables (Ministry of Labour 2019) are the two French decompression references. They serve different audiences and meet different regulatory requirements.
Comparison table
| Criteria | MN90 | MT2019 |
|---|---|---|
| Origin | French Navy (1990) | Official Journal (2019) |
| Use | Recreational, FFESSM | Professional diving |
| Gas | Air only | Air, Nitrox, Heliox |
| Max air depth | 65m | 75m |
| O₂ stops | No | Yes (6m and 12m) |
| Number of tables | 3 (main + 2 successive) | 18 (3 annexes) |
| Conservatism | Standard | More conservative |
| Legal requirement | No (FFESSM reference) | Yes (Labour Code) |
MT2019 advances
Oxygen decompression
MT2019 introduces pure oxygen stops (Tables 4 and 5), significantly reducing decompression times. A 20-minute air stop can be reduced to 8 minutes on O₂ — a major time saving for professionals doing multiple daily dives.
Integrated Nitrox
The Nitrox equivalence system (Table 7) allows using oxygen-enriched mixtures to reduce nitrogen loading. A diver on Nitrox 32% at 30m gets the same stops as an air diver at 25m.
Heliox for depth
Annex 2 covers Heliox mixtures (helium + oxygen), essential beyond 60m to avoid nitrogen narcosis.
Which to use?
- Recreational N1-N4 → MN90 Tables
- Professional diver → MT2019 Tables (legal requirement)
- Technical Trimix/Heliox → MT2019 Annex 2 or planning software
- Dive computer → Bühlmann ZH-L16