What it does
NordTek helps divers check a single recreational no-decompression dive plan, estimate gas needs, calculate SAC/RMV, and check MOD limits.
Dive planning and gas tools
Plan your dive.
Check your gas.
Know your limits.
A serious dive planning toolkit for checking no-decompression limits, gas needs, SAC/RMV, MOD, best mix, and trimix fill math without clutter.
Core tools
Choose the tool you need.
Start with the main Dive Planner, or jump into a focused calculator for SAC/RMV, gas planning, MOD, best mix, or trimix blending.
Built for quick planning
Practical tools, no distractions.
NordTek keeps the homepage simple and sends divers quickly into the tool they need.
NDL checksTable-style recreational no-stop planning.
Gas awarenessRequired gas, reserve, end pressure, and margin.
Mix supportMOD labels, best mix guidance, and trimix blending beta tools.
Mobile-firstBuilt toward a practical app-like workflow.
Coming Soon
NordTek will grow step by step without making the current tools harder to use.
User profilesSaved dive plans and personal SAC history.
Dive logSave dives and review gas consumption trends.
Offline appA separate app/PWA workflow after the website is polished.
Tech toolsAdvanced gas tools are separated from the recreational planner.
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Personal project note.
This is a personal dive planning project I created to simplify my own dive planning and calculations. I’ve made it publicly available primarily so I can access it wherever I am. It’s continuously evolving, with new features and improvements added over time.
NordTek is not an official dive planning service, certification agency, training platform, commercial product, dive computer, or substitute for training and judgment. You are responsible for your own dive decisions.
About NordTek
Recreational dive planning, kept simple.
NordTek Dive Planner is built as a personal planning aid for recreational scuba diving and gas calculation workflows. The goal is to keep the app clean, fast and understandable before adding advanced systems like accounts, saved plans and future technical diving modes.
About NordTek Dive Planner
NordTek Dive Planner is a personal recreational scuba diving planning and gas calculation tool designed to help estimate no-decompression limits, gas requirements, reserve volumes and dive logistics.
The planner provides quick calculations to support safer planning, while keeping advanced gas tools clearly separated from recreational dive planning.
Personal project note
NordTek Dive Planner is a personal scuba planning and gas calculation project built primarily for my own learning, planning workflow, and dive-related calculations. It is publicly accessible because it is hosted online, but it is not an official dive planning service, certification agency, training platform, or commercial product. Use it only as a calculation aid alongside proper training, gas analysis, dive computers, tables, local procedures, and personal judgment.
Current focus
- Recreational air dive planning
- No-stop limit awareness
- Gas and reserve checks
- Simple mobile-friendly UI
Not a substitute
This planner does not replace formal training, agency standards, dive computers, tables, gas analysis, local procedures, or real judgment before a dive.
Future direction
- User profiles and saved plans
- Repetitive dive planning
- Best Mix and Trimix Blender improvements
- Separate technical mode later
Help / Reference
NordTek reference and FAQ.
Use this page to understand what the current beta tools do, how NordTek calculates results, and where the important limitations are. The full learning library and feedback/contact options will grow after the v1.7.2 release.
Personal project note
NordTek Dive Planner is a personal scuba planning and gas calculation project built primarily for my own learning, planning workflow, and dive-related calculations. It is publicly accessible because it is hosted online, but it is not an official dive planning service, certification agency, training platform, or commercial product. Use it only as a calculation aid alongside proper training, gas analysis, dive computers, tables, local procedures, and personal judgment.
Current beta limitations
Beta v1.7.2 supports single-dive and two-dive recreational air table planning only. It does not support more than two dives, nitrox repetitive planning, decompression planning, altitude adjustments, cold/strenuous condition rules, ascent profile modelling, missed-stop handling, emergency gas-sharing decisions, multi-gas dive plans, personal dive computer algorithms or instructor-level planning decisions.
Recreational planner vs gas tools
NordTek separates recreational dive planning from advanced gas calculation tools. The Dive Planner remains recreational-only, while tools like Trimix Blender are beta calculation aids for trained users.
Formula Reference
Every formula used by NordTek.
This section explains the calculation logic in plain language. The formulas are simplified planning estimates using metric units: metres, bar, litres and minutes. They are meant to make the results understandable, not to replace formal dive planning training.
Ambient pressure / ATA
ATA = depth ÷ 10 + 1NordTek uses ATA to estimate how much pressure the diver is under at a given depth. At the surface the pressure is 1 ATA, and every 10 m of seawater adds roughly 1 ATA.
Used by: Dive Planner gas mode, SAC/RMV, Gas Planner, MOD, Best Mix and END.
No-stop table lookup
table depth = next listed depth equal to or deeper than planned depth NDL remaining = table NDL − planned bottom timeThe recreational Dive Planner rounds your planned depth up to the next available table depth, then compares your planned bottom time with that no-decompression limit.
Used by: Dive Planner NDL Only and NDL + Gas modes.
Repetitive dive table logic
Dive 1 depth + bottom time → end pressure group surface interval → new starting group ESDT = RNT + actual bottom time adjusted NDL = table NDL − RNT minimum SI = first table bracket where Dive 2 time ≤ adjusted NDLFor the two-dive repetitive planner, NordTek uses table lookups to find the end group, applies the surface interval, then adds residual nitrogen time to the planned second dive. If the entered interval is too short, NordTek searches later surface interval brackets and shows the first one that makes the second dive fit the table.
Used by: Repetitive Dives mode in the Dive Planner.
Gas used from pressure drop
gas used = cylinder volume × (start pressure − end pressure)This converts the pressure you used during a real dive into free gas litres. For example, using 100 bar from a 12 L cylinder equals about 1200 L of gas.
Used by: SAC/RMV Calculator.
SAC / RMV
SAC/RMV = gas used ÷ dive time ÷ ATA at average depthThis normalizes your gas use back to the surface, so a deep dive and a shallow dive can be compared more fairly. NordTek shows this as litres per minute.
Used by: SAC/RMV Calculator, and as an input for gas planning.
SAC result scale
Very Low < 10 · Low 10–15 · Typical 15–20 · Elevated 20–25 · High 25+After calculating SAC/RMV, NordTek places the result on a simple interpretation scale. This does not judge whether a dive is safe; it only helps the user read the number.
Used by: SAC/RMV Calculator result badge and scale.
Gas required for a planned dive
profile gas = SAC/RMV × ATA at planned depth × planned time safety stop gas = SAC/RMV × ATA at 5 m × 3 min gas required = profile gas + safety stop gasThe Gas Planner estimates how much gas the planned profile may use. If the safety stop is enabled, NordTek adds a 3 minute stop at 5 m.
Used by: Gas Planner and Dive Planner NDL + Gas mode.
Usable gas and reserve
total gas = cylinder volume × fill pressure reserve gas = cylinder volume × reserve pressure usable gas = total gas − reserve gasNordTek treats the reserve as gas you plan not to spend during the main dive. The gas check compares the estimated required gas with the usable gas after reserve.
Used by: Gas Planner and Dive Planner NDL + Gas mode.
End pressure and gas margin
pressure used = gas required ÷ cylinder volume estimated end pressure = fill pressure − pressure used gas margin % = (usable gas − gas required) ÷ usable gas × 100These formulas translate gas volume back into bar, so the result feels practical on a pressure gauge. The margin shows how much usable gas remains after the estimate.
Used by: Gas Planner and Dive Planner NDL + Gas mode.
Gas mix composition
Nitrox N₂ = 100 − O₂ Trimix N₂ = 100 − O₂ − HeFor Nitrox, the remaining gas after oxygen is treated as nitrogen. For Trimix, NordTek subtracts both oxygen and helium to find the remaining nitrogen.
Used by: MOD Calculator, Best Mix naming logic and Trimix Blender verification.
Maximum Operating Depth / MOD
MOD = (PPO₂ limit ÷ O₂ fraction − 1) × 10MOD estimates the maximum depth for a breathing gas at a chosen oxygen partial pressure limit. NordTek shows MOD at PPO₂ 1.4 and 1.6.
Used by: MOD Calculator and cylinder label generator.
Best Mix
O₂ fraction = PPO₂ limit ÷ ATA O₂ percentage = O₂ fraction × 100Best Mix works backwards from your planned maximum depth and PPO₂ limit to estimate the maximum oxygen percentage for that depth.
Used by: Best Mix Calculator.
Equivalent Narcotic Depth / END
equivalent ATA = planned ATA × narcotic fraction of mix ÷ narcotic fraction of air O₂ + N₂ model: narcotic mix fraction = (O₂ + N₂) ÷ 100, narcotic air fraction = 1 N₂-only model: narcotic mix fraction = N₂ ÷ 100, narcotic air fraction = 0.79 END = (equivalent ATA − 1) × 10END is a comparison estimate for narcosis. NordTek lets you choose whether oxygen plus nitrogen are treated as narcotic, or nitrogen only.
Used by: MOD Calculator when Trimix END options are shown.
Trimix partial-pressure blending
current gas bar = current pressure × current fraction target gas bar = target pressure × target fraction add air = (target N₂ bar − current N₂ bar) ÷ 0.79 add helium = target He bar − current He bar add oxygen = target O₂ bar − current O₂ bar − (add air × 0.21)The Trimix Blender estimates how many bar of helium, oxygen and air are needed to move from the current cylinder contents to the target mix.
Used by: Trimix Blender — BETA. This is ideal math only and must be verified with analyzer readings and proper blending procedures.
Trimix stop pressures
stop pressure after He = current pressure + added He stop pressure after O₂ = stop pressure after He + added O₂ final pressure = current pressure + added He + added O₂ + added airThese are the pressure targets shown during the ideal partial-pressure fill sequence.
Used by: Trimix Blender — BETA.
Trimix final mix verification
final O₂ % = (current O₂ bar + added O₂ + added air × 0.21) ÷ final pressure × 100 final He % = (current He bar + added He) ÷ final pressure × 100 final N₂ % = 100 − final O₂ % − final He %NordTek recalculates the final gas composition after the estimated fill steps so the displayed final mix can be checked against the target.
Used by: Trimix Blender verification summary.
Free gas litres and price estimate
free gas litres = cylinder volume × gas added in bar gas cost = free gas litres × price per litre total cost = helium cost + oxygen costWhen price estimation is enabled, NordTek converts the helium and oxygen additions into free gas litres and multiplies them by your local price per litre.
Used by: Trimix Blender optional price estimate.
What NordTek is
NordTek Dive Planner combines a personal recreational Dive Planner with a separate calculator suite for SAC/RMV, gas planning, MOD, best mix, and beta trimix blending math.
What NordTek is not
NordTek is not a dive computer, instructor, certification agency, decompression planner, gas analyzer, official dive planning service, commercial product, or replacement for training and judgment.
Dive Planner
- Single-dive and two-dive repetitive air mode in Beta v1.7.2
- Depth is rounded up to the next table depth
- NDL + Gas mode adds a gas consumption check
- More than two dives and nitrox table planning are not included yet
SAC / RMV Calculator
NordTek calculates surface-equivalent gas consumption from cylinder size, pressure used, dive time, and average depth. Use real dive data, not guessed numbers.
Gas Planner
Gas required is estimated from SAC/RMV × ATA × time. NordTek uses planned maximum depth for a conservative gas check and subtracts the selected reserve before judging usable gas.
MOD Calculator
MOD is calculated from oxygen percentage and PPO₂. The upgraded MOD tool also shows mix composition, optional END, and a cleaner cylinder label.
Best Mix Calculator
Best Mix calculates the oxygen percentage for a desired maximum depth and PPO₂ limit, then suggests a rounded fill value when appropriate.
Trimix Blender — BETA
This beta tool is only an ideal partial-pressure math estimate for trained gas blenders using appropriate oxygen-clean equipment and procedures. Always analyze the final cylinder before diving.
Accounts and saved plans
User profiles, saved dive plans, personal SAC history, and dive logs are planned for later. Beta v1.7.2 keeps the calculators usable without login.
Feedback and contact
A proper contact channel will be added later. For Beta v1.7.2, the focus is keeping the planning tools stable before adding feedback forms, accounts and saved plans.
Account
Accounts are coming later.
Accounts, saved dive plans, personal SAC/RMV history, and dive log saving will be added in a future NordTek version. For now, the calculators work without an account.
Beta v1.7.2 · Recreational mode
Dive Planner
Single or two-dive repetitive air planning with optional gas consumption for single dives.
Single-dive and two-dive repetitive air planning. Enter your own depth, time and surface interval, then calculate the plan.
Planned Maximum Depth
M
Planned Bottom Time
MIN
Safety Stop
Enter your dive details and press Calculate
NordTek will check the selected no-decompression planning limit.
Table Depth Used
—
No-Stop Limit
—
NDL Remaining
—
Safety Stop
—
Required fields are intentionally blank so the plan is based on your own inputs.
How this planner works
NordTek checks a single recreational air dive against a simple no-stop limit table. Your planned depth is rounded up to the next available table depth for a more conservative check.
What NDL means
NDL means no-decompression limit. It is the maximum planned bottom time at a given depth before mandatory decompression procedures would be required by the selected table/computer model.
Limitations and safety notes
Beta v1.7.2 is a two-dive recreational air table estimate only. It does not handle more than two dives, nitrox repetitive planning, decompression, altitude adjustments, cold/strenuous condition rules, ascent profile modelling, missed stops, emergency gas sharing, personal dive computer algorithms or mixed-gas dive profiles.
Beta v1.7.2 uses public NOAA-style air table logic for single-dive and two-dive recreational air planning only. More than two dives, nitrox repetitive planning, decompression planning, altitude/cold/strenuous adjustments and personal computer algorithms are not included.
Beta v1.7.2 · Calculator suite
SAC Calculator
Calculate your surface-equivalent gas consumption from real dive data.
Presets only fill the cylinder volume. You can still enter any size manually, for example 18L.
Cylinder Volume
L
Starting Pressure
BAR
Ending Pressure
BAR
Dive Time
MIN
Average Depth ?
M
Your Gas Consumption Rate
—L/min
—
Surface-equivalent gas consumption based on your real dive data.
SAC/RMV varies with workload, stress, equipment, current, temperature, buoyancy and experience.
How SAC / RMV is calculated
NordTek uses: gas used in litres ÷ dive time ÷ ATA at average depth. Gas used is calculated from cylinder volume × pressure used.
SAC vs RMV — what's the difference?
SAC and RMV are often used interchangeably by recreational divers. NordTek reports a surface-equivalent litres-per-minute rate that is closer to RMV, while keeping the familiar SAC wording.
Don't know your average depth?
For a more accurate SAC test, descend to a stable depth such as 10–15 m, swim normally for 10–15 minutes, and record start pressure, end pressure, time and depth.
Enter your cylinder, planned profile, safety stop, reserve and SAC/RMV, then calculate the gas estimate.
Presets only fill the cylinder volume. You can still enter any size manually, for example 18L.
Cylinder Volume
L
Cylinder Fill Pressure
BAR
Planned Maximum Depth
M
Planned Dive Time
MIN
Planned time is treated as the main dive/profile time. Add a safety stop below if you want it included in the estimate.
Safety Stop
Minimum Reserve Pressure
BAR
Your Gas Consumption Rate ?Calculate yours ›
L/MIN
SAC vs RMV — What's the difference?
SAC and RMV are often used interchangeably. NordTek calculates surface-equivalent gas consumption in L/min, which is technically RMV-style, while SAC is the familiar recreational term.
—
—
Gas Required
—
Usable Gas
—
End Pressure
—
Safety Margin
—
Reserve Remaining
—
How gas required is calculated
NordTek uses: Gas Required = SAC/RMV × ATA × Time, plus the selected safety stop if included. ATA increases with depth, so gas use rises as the dive gets deeper.
Why NordTek uses planned maximum depth
Gas planning is more conservative when it uses planned maximum depth instead of average depth. This helps account for ascent delays, workload, buddy issues and safety stops.
Why reserve pressure matters
The reserve is gas you intend not to use during the main dive. NordTek subtracts reserve gas before deciding whether the planned profile has enough usable gas.
Enter the analyzed gas mix. NordTek shows composition, MOD at PPO₂ 1.4 and 1.6, optional END, and a cylinder label.
Gas Type
O₂ Percentage
%
MOD Result
Enter the gas mix and press Calculate MOD.
Gas Mix
Mix
—
Composition
O₂
—
He
—
N₂
—
Gas Type
—
Safe Depths
MOD 1.4
—
MOD 1.6
—
Hypoxic gas warningThis mix has low oxygen content and may not be breathable at the surface. Use only with appropriate training and travel gas planning.
Enter the required gas values, then press Calculate MOD. Generate Cylinder Label creates a separate label card after the gas mix has been validated.
Cylinder Label
—
MOD 1.4
—
MOD 1.6
—
Composition
—
Calculated MODs are shown with one decimal. Label MODs should be rounded down according to your local procedure.
Date: __________ Initials: __________
What MOD means
MOD is the maximum operating depth for a gas at a selected PPO₂. Going deeper increases oxygen partial pressure and oxygen exposure risk.
END is not the same as MOD
MOD is about oxygen partial pressure. END is a narcosis comparison model for a chosen depth and gas mix. Some divers count oxygen as narcotic; others count nitrogen only. END is a comparison estimate, not a decompression or safety limit.
Limitations and safety notes
Always analyze your gas, label the cylinder, match your dive computer settings, and follow your training and agency limits. NordTek is a calculation aid only.
Calculate the oxygen percentage for a desired maximum depth and PPO₂ limit. Values outside recreational nitrox ranges are clearly flagged.
Desired Maximum Depth
M
PPO₂ Limit
Manual PPO₂ Limit
Best Mix
—
Depth
—
PPO₂ Limit
—
Calculated Max O₂
—
Practical Fill
—
Ask Fill Station For
—
PPO₂ With Suggested Fill
—
—
How Best Mix is calculated
NordTek uses: O₂ fraction = PPO₂ limit ÷ ATA. ATA is depth ÷ 10 + 1. The calculated value is then shown as a percentage.
Rounded recreational value
When the calculated result is within a normal nitrox range, NordTek suggests a rounded EAN value. Always follow your training, fill station procedures and oxygen limits.
Trimix Blender — BETA. This is an ideal math estimate only, not a complete fill procedure. For trained gas blenders using appropriate oxygen-clean equipment, analyzer verification and local procedures.
Blending Mode
Cylinder Size
L
Price Estimate
Optional. Enable this only if you want NordTek to estimate helium and oxygen cost from local price per free litre.
Helium Price / L
/L
Oxygen Price / L
/L
Current Cylinder
Current Pressure
BAR
Current Gas
Current O₂
%
Current He
%
Target Cylinder
Target Pressure
BAR
Target Gas
Target O₂
%
Target He
%
—
—
What to Add
Add Helium
—
Helium Free Gas
—
Stop Pressure After He
—
Add Oxygen
—
Oxygen Free Gas
—
Stop Pressure After O₂
—
Add Air
—
Air Free Gas
—
Final Pressure
—
Verification Summary
Final Mix
—
Final Composition
—
—
Trimix fill safety note
This is an ideal math estimate only, not a complete fill procedure. Real blending requires trained gas blender procedures, oxygen-clean equipment, temperature settling, analyzer readings, cylinder labeling and local standards. Analyze the final cylinder before diving.
Blending modes
Version 1 implements partial-pressure blending. The UI is structured so continuous-flow blending can be added later without redesigning the whole tool.