Calculator tools
Find The Right Tools For Your Project.
Promax calculator tools are grouped below by application, including rainwater, underground tank design, stormwater compliance, and wastewater planning. Start with the section that best fits your project, then choose the calculator that matches the decision you need to make.
Rainwater
Rainwater & domestic water
Promax rainwater tools are designed to make early planning easier, whether you are working out how much water storage a property needs or selecting the right slimline solution for a tighter site. These tools help turn broad requirements into more practical next steps, giving homeowners, builders, and specifiers a clearer path forward.
Rainwater Tank Size Calculator
The Rainwater Tank Size Calculator helps estimate an appropriate storage volume based on roof catchment area, rainfall zone, and expected water demand. It is a practical starting point for households looking to improve water security, reduce reliance on mains supply, or plan a rainwater system with greater confidence before moving into product selection.
Rainwater Tank Size Calculator
Slimline Specification Tool
The Slimline Specification Tool helps identify the right slimline tank setup for sites where space, access, and layout all play an important role. It is designed to guide users through the selection of tank size, fittings, and pump configuration so the final solution is better matched to the realities of the site and the intended use of the system.
Slimline Specification Tool
Underground
Underground tank design
Promax underground tools are built to support more informed planning and specification for projects where below-ground storage is required. Whether the focus is installation conditions, system layout, or hydraulic performance, these tools help users work through the key variables before moving further into design, documentation, or procurement.
Underground Specification Tool
The Underground Specification Tool helps match Promax underground tanks to site conditions such as cover depth, traffic loading, riser requirements, and installation setup. It is intended to support builders, contractors, and installers who need a clearer understanding of what configuration is suitable for the project and what practical factors need to be considered before installation begins.
Underground Specification Tool
Enduro Partial Volume Calculator
The Enduro Partial Volume Calculator helps determine partial fill volumes and critical invert levels for Promax Enduro underground tanks. This is especially useful on projects involving detention, retention, or controlled outflow, where accurate volume and level calculations are important for design confidence, system performance, and more effective project planning.
Enduro Partial Volume Calculator
Stormwater
Stormwater compliance
Promax stormwater tools are designed to simplify key calculations for detention and retention planning, helping engineers, developers, and specifiers work through project requirements with greater clarity. These tools provide practical support during early assessment and design development, making it easier to understand likely system needs before progressing further.
SMAF Calculator
The SMAF Calculator is designed to support stormwater planning by simplifying Auckland SMAF detention and retention calculations. It helps users assess stormwater outcomes more efficiently and provides a clearer starting point for projects where compliance, attenuation, and site performance all need to be considered together.
SMAF Calculator
Stormwater Detention PRE-POST Calculator
The Stormwater Detention PRE-POST Calculator helps compare pre- and post-development runoff to support detention planning and broader stormwater assessment. It is a useful tool for projects where development changes site hydrology and where a clearer understanding of runoff impact is needed to inform design decisions, consent pathways, and detention requirements.
Detention PRE-POST Calculator
Wastewater
Wastewater & septic
Promax wastewater tools are intended to support early planning for on-site wastewater systems, helping users work through sizing requirements and site considerations before moving further into design or installation. They are particularly useful for rural and residential projects where a practical starting point is needed to guide decision-making.
Septic Tank & Soakage Field Sizing Tool
The Septic Tank & Soakage Field Sizing Tool helps estimate suitable septic tank and soakage field requirements based on site-specific conditions and wastewater design needs. It gives homeowners, plumbers, and specifiers a more informed starting point for planning on-site wastewater systems, making it easier to understand likely system requirements before progressing to detailed design or approval.
Septic Tank & Soakage Field Sizing Tool
Need help with product selection?
If your project needs more guidance, the Promax team can help you work through tank selection, site considerations, and the next steps from early sizing through to a suitable solution. This is a useful option for projects that fall outside a straightforward calculator pathway or where extra support is needed to confirm the right approach.
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- Spec, compliance and sizing guidance included
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