HOAI Calculator for Architects and Engineers

HOAI in Brief

The Honorarordnung für Architekten und Ingenieure (HOAI) is the “price regulation” for planning and consulting services in Germany. It defines how architects and engineers can bill for their services, thereby ensuring transparency and comparability. Since its introduction in 1977, the HOAI has been revised several times to align it with current legal and economic developments. The HOAI 2009 was the first to introduce minimum and maximum rates. The current version has been in force since 2021, in which fees are still recommended but are no longer mandatory — providing greater flexibility while also requiring a little more negotiating skill on both sides.

Automatically Calculate Fees According to HOAI

There are numerous free tools available online for calculating fees according to HOAI — for example the calculator at HOAI.de. These helpers are always practical, because the legal text runs to around 120 pages and contains a large number of tables in which finding the right rates requires considerable patience.

But simply calculating the fee rates is only the first step. Ultimately, a complete quote also needs to be created. This is exactly where projectfacts comes in: the software features an integrated HOAI calculator, so there is no need to switch to external tools and tediously transfer figures. Instead, you simply enter the key base data such as construction costs and service description — and projectfacts automatically determines the correct rates. These flow directly into your quote, which is then available as a PDF in your corporate design and can be sent immediately. Creating quotes according to HOAI has never been so straightforward!

Select the Appropriate Fee Scale

To calculate the appropriate fees for your quote, you first define some general parameters. These include in particular:

• HOAI version: The two most recent versions from 2013 and 2021 are available for selection.
• Service description: Here you determine the type of service, for example a development plan, landscape plan, or traffic facilities. The service description also defines which service phases and how many are required for the overall service.
• Fee zone: The fee zone indicates the level of difficulty of the planning service. Depending on the service description, different numbers of zones are available — from Zone I (very low requirements) to Zone V (very high requirements). For guidance, the HOAI contains concrete examples for the correct classification.
• Fee rate: The fee tables in the HOAI define a range within which the fee moves — from the minimum to the maximum rate.

Intermediate values such as the quarter rate, middle rate, or three-quarter rate can also be selected in between, resulting from linear interpolation.

The actual calculation is then based on a key figure that varies depending on the service description — for example the chargeable construction costs in euros or an underlying area in hectares. From this reference value and the selected general parameters, the system automatically determines the fees for the individual service phases.

Break Down Service Phases in the Quote

With just the click of a button, projectfacts calculates the desired fees and automatically transfers all service phases of the selected service description into your quote. If you wish, you can store templates so that the names and descriptions of the line items are predefined. A finished structure might then look something like this:

1. Preliminary investigation	2%	1,413.49€
2. Preliminary design	7%	4,947.22€
3. Design development	15%	10,601.18€
4. Approval planning	3%	2,120.24€
5. Detailed design	25%	17,668.63€
6. Preparation of tendering	10%	7,067.45€
7. Participation in tendering	4%	2,826.98€
8. Project supervision – construction supervision and documentation	32%	22,615.84€
9. Project support	2%	1,413.49€
Total		70,674.50€

You can see the result in real time as a PDF file and can send or print it immediately.

Changes to the quote are possible at any time: simply adjust the general parameters and the service phases are updated on request. Additional cost components can also be added without any difficulty, such as percentage surcharges or additional services with fixed amounts. Several areas or objects can even be combined in a single quote and billed according to different service descriptions.

Create HOAI Invoices Simply and Flexibly

With projectfacts you not only create convincing HOAI quotes, but also bring your projects to billing quickly and straightforwardly. You have full flexibility here:

• Billing according to payment plan: You define fixed dates — projectfacts creates your invoices automatically at the desired time.
• Billing according to project progress: As soon as a project section is completed, the corresponding service item automatically becomes billable. This keeps you fully informed at all times and saves valuable time.

And that is just the beginning: with many further options, you can adapt the billing process exactly to your way of working — efficiently, transparently, and without detours.

Try it out: arrange an appointment now with our consulting team and discover how simple and professional HOAI billing can be with projectfacts!