Gas Pipe Sizing
Size a gas pipe run in seconds against AS 5601.
The Clarus Quick Gas Calculator handles single-run gas pipe sizing for natural gas and LP gas across six supported materials. Pick a pressure or pressure-drop preset, or drop into custom mode for non-standard supply and drop conditions. Either way, you get a recommended pipe size in the material of your choice with full calculation exports that your team can review, explain, and defend.
Modes
For the work you do most days. Choose a pressure preset (gas type, pipe material, supply pressure, allowable drop), enter the gas load in MJ/h and the index length in metres, and Clarus returns the smallest DN that passes the standard, using the same gas calculations found in AS 5601.
When the project specifies a supply pressure or pressure drop the standard presets don't cover. Enter your own supply pressure and allowable drop, and the calculator runs formula-based sizing directly, with a full Reynolds number, friction factor, and pressure-drop solve in the result.
Materials
The calculator uses the correct internal diameter and material standard table for each, so velocity and pressure-drop numbers match the pipe, not a generic estimate.
Natural gas and LP gas / propane are both supported, with gas-specific properties (density, kinematic viscosity, calorific value) wired into the hydraulics. Switching between the two is a dropdown, not a different tool.
Results
Every Quick Gas Calculation returns a complete, auditable result.
With its internal diameter, ready to specify.
Every candidate DN in the chosen material with its tabulated capacity (MJ/h) and pass/fail status against your demand.
For the selected size: supply pressure (gauge and absolute), allowable drop, calculated drop, and pass/fail flag. The numbers a reviewer needs to audit the design.
Reynolds number, friction factor, velocity, calculated pressure drop. Not just the answer, but the working.
Entered length, tabulated length used, effective length after the 1.5x fitting allowance, and the allowance factor itself. The basis the result was sized against, in writing.
When conditions fall outside the deemed-to-satisfy envelope, with reasons listed. The compliance boundary is on the result, not hidden.
Why it's used
The generated tables are Appendix F equivalents, regenerated from the same calculations used in the standard.
Generated tables for the everyday job, sized in seconds. Custom mode for the project that specifies a non-standard supply pressure or drop. Same tool, no switching, same shape of output.
Clarus shows you every candidate in the material with capacity, calculated pressure drop, velocity, and the standard's pass/fail flag per row. The "would the next size down work?" conversation is answered on screen.
Reynolds number, friction factor, velocity, calculated pressure drop, supply pressure gauge and absolute. The actual solve, not summary numbers, so the calculation defends itself in review.
When a project pushes conditions past the generated-table envelope, the formula path still calculates and raises the professional-review acknowledgement. The work continues; the compliance boundary stays visible.
Copper AS 1432 Type B, Copper NZS 3501, Steel AS 1074 Medium, Polyamide and PE for buried supply, and PVC-HI, each with the correct internal diameter and material standard reference table.
Save calculations as snapshots tied to a moment in time and attach them to a project. Each PDF is stamped with gas type, material, supply pressure, allowable drop, index-length basis, and standards table version, safeguarding you against compliance disputes.
When it grows
The Quick Gas Calculator is for single-run sizing, fast. When a design grows into a branched gas network, switch to Schematic Studio, a professional drafting environment that sizes every branch automatically as you sketch. Produce issue-ready schematics and advanced system calculations in minutes, with the same standards-aligned outputs behind every run.
Spin up a free trial and size your first run in seconds against AS 5601, with the full pressure-drop solve and a standards-stamped PDF you can defend in review.
Start your first gas pipe sizing calculation