Dive Tools by Chris Uriarte

MOD, Best Mix, EAD, END, and ppO₂ calculators.

Quick calculators for technical divers: Maximum Operating Depth (MOD), best nitrox mix for a planned depth (with optional depth-buffer safety margin), Equivalent Air Depth (EAD), ppO₂ at depth, and Equivalent Narcotic Depth (END) for trimix. Supports feet and meters.

Illustrates maximum dive times and gas use for a given multi-segment profile using the Bühlmann algorithm.

Educational and reference tool that illustrates recreational no-decompression limits and gas consumption across a multi-segment dive profile. Models Bühlmann ZH-L16C tissue saturation with configurable conservatism (gradient factors), Nitrox support, optional ascent / safety stop modeling, and per-segment NDL. Not for planning real dives.

View and compare specs of multiple cylinder types from major manufacturers.

Side-by-side spec comparison of up to three scuba cylinders. Choose from ~90 aluminum and steel cylinders across Catalina, Luxfer, Metal Impact, Thunderbird, Faber, OMS, PST, and Worthington. Filter by material or capacity, switch between imperial and metric units.

Conversion of common units of measure used by divers.

Live bidirectional conversions for the units divers use most: feet ↔ meters, psi ↔ bar, pounds ↔ kilograms, cubic feet ↔ liters, °F ↔ °C, and depth ↔ ATA in both unit systems. Type in either box to update the other instantly.

Calculate your SAC rate from a logged dive, or predict gas use from a known RMV.

Two modes: enter a logged dive's start/end pressure, time, average depth, and tank specs to derive your SAC (psi/min or bar/min) and RMV (cu ft/min or L/min); or enter a known RMV with a planned profile to predict gas use and pressure drop. Tank-aware so pressure-based and volume-based numbers stay consistent. Supports psi/cu ft and bar/L.

Calculates rock-bottom gas reserve for a shared-air emergency ascent.

Compute the minimum gas reserve to keep in your tank to safely return both you and a buddy to the surface in a gas-share emergency. Inputs cover depth, RMV, stress factor, ascent rate, and an optional safety stop; outputs are the surface-equivalent gas volume required and the corresponding pressure to leave in your tank. Supports psi/cu ft and bar/L.

Multi-mode gas blending application.

Partial-pressure gas blender for nitrox and trimix. Three modes: know the target mix and get fill instructions, know what you added and get the resulting mix, or specify O₂/He/top-off amounts directly for a free-form blend. Supports psi and bar.

Calculates turn pressures by volume when buddies dive with different-sized tanks.

Match turn pressures by volume when buddies dive with different-sized tanks. Enter each diver's tank config and fill pressure, pick a reserve rule (thirds, halves, sixths, or custom), and see who's the controlling tank plus each diver's matched turn pressure. Supports psi/cu ft and bar/L.

Pre-dive equipment checklist for backmount open-circuit tec diving, grouped by category.

Pre-dive equipment checklist for backmount open-circuit technical diving (doubles + deco bottles). Items are grouped into categories (Core, Exposure, Computers, Gas, Lighting, Safety, Spares, Documentation) with per-category progress, drag-and-drop or arrow-button reorder within a category, custom items, and Validate / Print / Email. State saves automatically to your browser.

Computes breathing-gas density at depth and flags densities above the modern safety threshold.

Given a gas mix (O₂/He/N₂) and depth, compute the breathing-gas density at depth in g/L. Color-coded against the Anthony & Mitchell thresholds of 5.2 g/L (recommended) and 6.2 g/L (hard ceiling), with a suggested helium fraction to bring the mix back to the safer threshold. Useful for tech and CCR divers planning trimix at deeper depths.

Suggests the optimal trimix bottom mix that meets your target ppO₂, narcotic depth, and gas-density limits with the least helium.

Given a maximum depth and target constraints (ppO₂, equivalent narcotic depth, and gas density), the optimizer finds the trimix mix with the smallest helium fraction that satisfies all three. Reports the achieved values at depth, identifies the binding constraint, and warns when the mix is hypoxic at the surface or when the targets are infeasible. Defaults follow modern conventions (5.2 g/L density target per Anthony & Mitchell, O₂ treated as narcotic).

Compares gas volume and pressure usage across two different types of cylinders.

Plan gas use across two different tanks. Enter Tank A's specs and the pressure you'll use on the dive — the calculator returns the volume of free gas consumed and the equivalent pressure that would be drawn from a different-sized Tank B. Independent psi/bar and cu ft/L unit toggles. (Note: This is a niche use case that I use when comparing gas usage on the on-board CCR O₂ to off-board bottles. There may be other uses for it.)

Compares CCR onboard O₂ use and CNS exposure across multiple setpoints.

Side-by-side comparison of three ppO₂ setpoints for a given dive profile. Models metabolic O₂ consumption plus loop top-off during descent, and shows per-setpoint O₂ cylinder use, accumulated CNS%, and projected cylinder pressure remaining. Supports psi/bar.

Displays the characteristics of a specific CCR diluent gas at depth.

For a specified nitrox or trimix diluent at a given depth and loop setpoint: shows loop PO₂, OC bailout PO₂, dil flush margin, gas density, and equivalent narcotic depth (END). Flags potential issues against PO₂, density, and flush-margin thresholds. Imperial and metric.

Configurable factory build checklist for the Dive Rite O₂ptima CM.

Dynamic assembly checklist for the Dive Rite O₂ptima CM / Choptima rebreather. Record build & dive info, check off steps with inline mV / voltage / gas-analysis fields, reorder steps to match your workflow, add custom steps, and print or save as PDF. State saves automatically to your browser.

Compares the total cost of diving a CCR vs. OC over a number of dives.

Compare the total cost of diving a Closed Circuit Rebreather versus Open Circuit Trimix or Nitrox over a configurable number of dives. Models gas, scrubber, oxygen, deco cylinders, and recoup period for CCR initial costs.

A regular guy’s attempt to answer common questions for locals and visitors looking to SCUBA dive in Palm Beach, Broward, Miami-Dade Counties, and the Florida Keys.

A regular guy’s attempt to answer common questions for locals and visitors looking to SCUBA dive in Palm Beach, Broward, Miami-Dade Counties, and the Florida Keys.