HOAI Calculator (Quick Estimate)
Use this free hoai rechner online to estimate planning fees for building services based on cost, fee zone, selected service phases (Leistungsphasen 1–9), and fee level.
Disclaimer: This calculator is an educational estimate, not legal or tax advice and not a binding HOAI offer. Always confirm with an architect/engineer for contract-ready numbers.
What is a HOAI Rechner Online?
A HOAI Rechner online is a digital tool that helps estimate architect and engineer fees according to the German fee framework (HOAI). In practice, many people use a quick calculator before requesting proposals, preparing budgets, or discussing scope with planning partners.
The biggest benefit is speed: you can test different project sizes, fee zones, and service phases in seconds. That makes it easier to understand how planning scope affects total cost.
How this calculator works
1) Construction cost as the starting point
The calculation starts with your net chargeable construction cost. The fee estimate scales with this value.
2) Fee zone for complexity
Projects with higher technical or planning complexity typically map to higher zones. As the zone increases, the estimated fee rate also increases.
3) Selected service phases (LPH 1–9)
Not every project needs all phases. If you only commission selected phases (for example LPH 1–4), this tool adjusts the result by the associated percentage weights.
4) Fee level: min, middle, max
Many fee discussions happen around a minimum, middle, or maximum level. The calculator shows all three, and highlights your selected level for quick comparison.
Why this is useful for clients and planners
- Budget planning: Get a rough planning-fee corridor early.
- Scope clarity: See the cost effect of removing or adding LPH phases.
- Negotiation support: Prepare better for fee discussions.
- Scenario testing: Compare small, medium, and large project assumptions quickly.
Example use case
Imagine a residential project with €500,000 net chargeable costs in Zone III. If all LPH phases are included, the fee estimate is naturally much higher than a limited commission (say LPH 1–4 only). This is exactly why online calculation is practical: you can visualize differences before contract drafting.
Important limitations to keep in mind
- Real projects may include special services and surcharges not reflected here.
- Actual contract terms can vary based on discipline and scope details.
- Regional market dynamics and project risks may influence final offers.
- This page provides a simplified model for orientation, not a legally binding result.
Frequently asked questions
Is this calculator legally binding?
No. It is a planning aid only. Treat it as a first estimate.
Can I use only selected phases?
Yes. Check or uncheck LPH 1–9 to reflect your intended commission scope.
Does the calculator include VAT?
Yes, if you activate the VAT option. You can also view net-only values by switching VAT off.
Final thoughts
A clear estimate can reduce uncertainty and improve project decisions. Use this hoai rechner online as your starting point, then verify final scope and fee details with a licensed professional before signing any agreement.