Units and rounding | DiveLogic Handbook

The units DiveLogic works in, and which direction each number is rounded so that the figure you read is the cautious one.

DiveLogic is metric everywhere. There is no imperial option, no unit setting and nothing to convert.

Quantity	Unit	Written as
Depth	metres	`45 m`
Time	minutes	`25 min`
Pressure	bar	`1.4 bar`
Volume	litres	`2400 L`
Gas fraction	percent	`21 %`, `21/35`
Gas density	grams per litre	`5.2 g/L`
Descent and ascent rate	metres per minute	`9 m/min`
Breathing rate	litres per minute	`15 L/min`
Temperature	degrees Celsius	`12 °C`
Altitude	metres above sea level	`1200 m`

Pressures are absolute, not gauge: 1 bar is the surface, not zero. Depth becomes pressure from the weight of the water above you, at 1025 kg/m³ for salt and 1000 kg/m³ for fresh, on top of the atmospheric pressure at your altitude. The 1 + depth ÷ 10 shortcut is not used anywhere, so a plan at 30 m in fresh water is not the same plan as one at 30 m in the sea. See Environment.

Which way numbers round

Number	Rounds	So that
Maximum operating depth	Down, to the whole metre	The depth limit you read is never deeper than the one the gas actually has. A MOD of 33.7 m is shown as 33 m.
Any other depth limit from a ppO₂	Down	Same reason.
Narcotic depth (END and EAD)	Up	A deeper narcotic depth is the stricter judgement of a mix.
Decompression ceiling	Up	A shallower ceiling would invite you to come up further than the model allows.
Stop depths	Up, onto your stop spacing	A stop sits at or below the ceiling, never above it.
Runtime and time to surface	To the nearest minute	These are summaries, not limits.

The first stop is the exception: the ceiling at the moment you leave the bottom is taken to the next stop depth toward the surface, and GF Low supplies the margin there. See Gradient factors.

A ceiling is rounded before it meets the stop grid, so a ceiling of 3.09 m lets you sit at the 3 m stop. All of this rounding is display only; the schedule is computed on the unrounded numbers throughout.