Dalton: Dive Gas Calculator
Nitrox & trimix calculator
Free · In-App Purchases
Know your gas. Trust your numbers. Now share them. Verified formulas, widgets, and link sharing. One-time purchase for Pro tools. No subscriptions, no account required.
Know your gas. Trust your numbers.
Dalton is the gas calculator that shows its work. Every result is verified against PADI Nitrox Tables, TDI Trimix Tables, and Shearwater manuals. Every formula is published with step-by-step derivations and source citations. No black boxes.
GAS CALCULATIONS
- MOD (Maximum Operating Depth): Find the safe depth limit for any gas mix based on your ppO2 tolerance
- Equivalent Air Depth: Calculate nitrogen loading equivalents for nitrox decompression planning
- Equivalent Narcotic Depth: Determine narcotic effects at depth for trimix planning
- Best Mix: Find the optimal oxygen percentage for your target depth
- Gas Properties: Calculate density, partial pressures, and breathing resistance at depth
DIVE PLANNING
- Return Number (Dalton Pro): Gas volume required for safe ascent — rule of thirds, fourths, or custom reserve fractions. The overhead environment gas management tool most divers do on paper or skip entirely
- Dive Profile Advisor (Dalton Pro): Plan multi-level dives with gas switches and depth segments
- Bottom Time Calculator (Dalton Pro): Determine available bottom time based on gas supply and consumption
Dalton Pro tools require a one-time in-app purchase. All gas calculation tools are free.
FORMULA REFERENCE
Tap any result to see the full formula derivation with source citations. Dalton is the only mobile gas calculator that publishes every formula it uses. Teach the math. Show the math.
SHARE YOUR CALCULATIONS
Share any result as a URL with a QR code. Recipients with Dalton installed open the calculation directly in the app. Everyone else sees a web preview with the full results. Dalton Pro tool links show a result summary before the in-app purchase prompt -- useful for team briefings where not everyone has the app.
Export formula cards as branded images. Send your gas plan to a buddy, post it in the group chat, or print it for the dive briefing whiteboard. One calculation, shared with the entire team in seconds.
HOME SCREEN AND LOCK SCREEN WIDGETS
- Quick Launch: A 2x2 grid that opens MOD, Best Mix, EAD/END, or Gas Properties with a single tap. No navigating through menus at the fill station
- Quick MOD Reference: Pre-computed MOD for your selected gas mix, available on home screen and lock screen in circular, rectangular, and inline formats. Glance at your lock screen and see your MOD without opening the app
- Both widgets are free
- All values are pre-computed inside Dalton. No calculation logic runs in the widget extension
SAFETY-FIRST DESIGN
- Three-tier safety warnings tied to recognized physiological thresholds
- Gas density tracking with 5.7 g/L threshold from Doolette and Mitchell research
- Configurable safety limits with ppO2 range from 1.2 to 1.6 bar
- Standard gas mix presets: Air, EAN32, EAN36, and common trimix blends
- Full gas range: air, nitrox, and trimix including hypoxic blends to 300m
- Offline-first design: no internet connection required
- No subscriptions, no ads, no account creation
Every calculation is verified. Every result is reliable.
A Tools for Divers, LLC product
Ratings & Reviews
- This app has not received enough ratings or reviews to display an overview.
Dalton 1.2 brings glanceable safety data to your Home and Lock Screens, hands-free calculations, and stronger safety checks on shared links.
• New Favorite Gas Mix Reference widget — pin a gas mix and reference depth, glance MOD, ppO₂, and gas density without opening the app. Three families for Home Screen and Lock Screen. Hard-fails to a safety placeholder when reference depth exceeds the mix's MOD.
• Ask Dalton with Siri Shortcuts — MOD, EAD, END, Best Mix, and Gas Density now work hands-free. Trimix-only calculations stay gated behind Technical Diver mode.
• Shared calculation links are validated against Dalton's safe-range rules before any tool state is populated. Links carrying unsafe values (ppO₂ > 1.6, O₂ ≥ 100%, depth > 200 m) are refused with a clear alert naming the offending field.
The developer, Tools for Divers, LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Provider
- Tools for Divers, LLC
- Size
- 12.5 MB
- Category
- Utilities
- Compatibility
Requires iOS 26.0 or later.
- iPhone
Requires iOS 26.0 or later. - iPad
Requires iPadOS 26.0 or later. - Mac
Requires macOS 15.6 or later.
- iPhone
- Languages
English and 5 more
- English, French, German, Italian, Japanese, Spanish
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Dalton Pro SAR 59.99
- Copyright
- © Tools for Divers, LLC 2026
