Cost estimate to DIN 276 using your own benchmark figures

A cost estimate to DIN 276 becomes reliable when its benchmark figures come from your own completed projects, are updated to today’s price level and all assumptions are laid open. The result is a range with an assumptions list. It is not a cost commitment, and it does not replace a designer’s service under the HOAI (German fee regulations for architects and engineers). It is meant for clients, property owners and project managers who have to estimate a budget before a designer is appointed or can deliver. Position as of November 2026.

Where the cost estimate stands

DIN 276 is titled “Kosten im Bauwesen” (costs in construction) and applies in the 2018-12 edition. I have not read the text of the standard for this article, because it is chargeable. I rely on several freely available sources: the DIN Media product page with its notes on replacement and changes, the table of contents from DIN, a seminar handout from the Baden-Württemberg Chamber of Architects that reproduces table 1 of the standard, lecture slides from the BKI cost information centre of the chambers of architects, a technical article from the Bavarian Chamber of Architects, and the HOAI. I have not seen a complete list of the stages from the text of the standard itself. Check the designations against the text of the standard before you copy them into your forms.

Together these sources name six stages of cost determination: cost framework (Kostenrahmen, lecture slides), cost estimate (Kostenschätzung), cost calculation (Kostenberechnung) and cost determination (Kostenfeststellung), all three from the HOAI, as well as Kostenvoranschlag and Kostenanschlag (technical article; roughly a priced forecast and a cost order estimate). The Kostenvoranschlag has been new since 2018 and sits between the cost calculation and the Kostenanschlag. The further a project advances, the deeper the cost breakdown goes. For the cost estimate the Chamber of Architects names the second level (previously the first) and for the cost calculation the third (previously the second). For the December 2008 edition, the HOAI requires at least the first level for the cost estimate and at least the second level for the cost calculation.

1. Cost framework earliest stage, before the cost estimate
2. Cost estimate preliminary design, HOAI work stage 2
3. Cost calculation design stage, HOAI work stage 3
4. Kostenvoranschlag new in 2018, priced bills of quantities
5. Kostenanschlag follows the Kostenvoranschlag
6. Cost determination at the end, HOAI work stage 8

Text version of the graphic

• 1. Cost framework: earliest stage, before the cost estimate
• 2. Cost estimate: preliminary design, HOAI work stage 2
• 3. Cost calculation: design stage, HOAI work stage 3
• 4. Kostenvoranschlag: new in 2018, priced bills of quantities
• 5. Kostenanschlag: follows the Kostenvoranschlag
• 6. Cost determination: at the end, HOAI work stage 8

Since 2018 the first level of the cost breakdown has eight cost groups. New is group 800, which was split off from the ancillary construction costs. The names come from table 1 of the standard as the Baden-Württemberg Chamber of Architects reproduces it (translations added by me):

Cost group	Designation
100	Land (Grundstück)
200	Preparatory measures (Vorbereitende Maßnahmen)
300	Building, construction (Bauwerk – Baukonstruktionen)
400	Building, technical services (Bauwerk – Technische Anlagen)
500	External works and open spaces (Außenanlagen und Freiflächen)
600	Fittings and works of art (Ausstattung und Kunstwerke)
700	Ancillary construction costs (Baunebenkosten)
800	Financing (Finanzierung)

In the HOAI, the cost estimate and the cost calculation are basic services of the designer. Annex 10 names in work stage 2 the “cost estimate to DIN 276, comparison with the financial framework” and in work stage 3 the “cost calculation to DIN 276 and comparison with the cost estimate” (my translation). For chargeable costs the HOAI still refers to DIN 276-1:2008-12 (section 4(1) HOAI, in the version retrieved on 13 November 2026). Under section 2(10) HOAI, the cost estimate is the approximate determination of costs on the basis of the preliminary design and the provisional basis for financing considerations. The Chamber of Architects points out that the new edition of DIN 276 does not change the basic services under the HOAI. In my assessment, a client who estimates a budget is not producing a designer’s service but comes close to its scope. That is why the estimate carries the note “budget estimate”.

Why your own benchmark figures

A benchmark figure is a cost value per reference unit, for example euros per square metre of gross floor area or usable floor area, broken down by cost group. The most reliable source is completed projects of your own house. There you know the standard, the location and the special features. The work lies in the preparation: invoice items must be assigned to cost groups, special cases adjusted and the reference quantity recorded for each project. How to track costs by cost group on an ongoing basis is covered in Cost monitoring to DIN 276: an overview.

A language model helps with the assignment. It reads invoices and cost determinations and proposes a cost group for each item. A specialist approves every assignment. The calculation is done in a spreadsheet or a fixed program. Without a project history of your own, the route would be licensed collections of benchmark figures. They may only be used within the terms of their licence, and I deliberately name no values from them here. The more completed projects there are, the more meaningful their spread is. With a single project there is no range but a single value, and it is marked as such.

1. Completed projectsFinal accounts, cost determinations, your archive
2. Benchmarks per cost group€ per m² of gross or usable floor area, with source
3. Price levelUpdated with the construction price index
4. ReserveContingencies as a separate line, with assumption
5. Estimate with rangeAssumptions list, method, no cost commitment

Text version of the graphic

• Layer 1 from the bottom: Completed projects, Final accounts, cost determinations, your archive
• Layer 2 from the bottom: Benchmarks per cost group, € per m² of gross or usable floor area, with source
• Layer 3 from the bottom: Price level, Updated with the construction price index
• Layer 4 from the bottom: Reserve, Contingencies as a separate line, with assumption
• Layer 5 from the bottom: Estimate with range, Assumptions list, method, no cost commitment

Price level: updating with the construction price index

Benchmark figures from older projects stand at the price level of their time. The construction price index of the Federal Statistical Office is used to update them. It applies to the new construction of conventionally built residential buildings, has the base year 2021 equal to 100 and includes VAT. It covers only the building. For land, external works or ancillary construction costs it therefore does not fit without further thought, and that belongs in the assumptions list. The reporting months of the statistic are three months apart, most recently August 2026, before that May 2026.

The latest publication of 9 October 2026 reports for August 2026 an increase of 5.5 per cent on August 2025 and of 1.0 per cent on May 2026. In May 2026 the year-on-year increase was 5.0 per cent. For office buildings the office reports 5.7 per cent, for the maintenance of residential buildings 6.0 per cent. So the residential building index does not automatically fit every type of building, and whether it is the right one for your project belongs in the assumptions list.

Two rules keep the calculation clean. First, the index includes VAT, so the estimate must be gross throughout or net throughout. Second, a fixed program works out the factor from the ratio of the index levels. Adding up annual rates would be wrong.

An example with invented data: five projects have benchmark figures for the building (cost groups 300 and 400) between 1,650 and 2,050 euros per square metre of gross floor area, all including VAT and at the price level of August 2025. A year later the increase of 5.5 per cent gives the factor 1.055, so 1,741 to 2,163 euros per square metre. For 3,000 square metres that comes to about 5.2 to 6.5 million euros. The spread of your own benchmark figures supplies the range, and it is part of the result.

What the AI does not do here

It does not read drawings and does not determine quantities. The reference quantity, that is the gross floor area or usable floor area of the new project, comes from your information, for example from a room schedule or a feasibility study. How certain that area is belongs in the assumptions list. If it changes later, the program recalculates the estimate, and the range shifts in a traceable way.

The language model does not pull the index together from memory either. A person reads the index levels from the publication of the Federal Statistical Office and enters them in the table with the reporting month. Every line of the estimate carries quantity, reference unit, benchmark figure, price level and source.

Contingencies, assumptions list and method

Contingencies appear as a separate line and are not built into the benchmark figures. The assumption behind it belongs with it, for example a percentage allowance with its reasoning. Which value you use is your decision. I name none here, because I could not substantiate one with a source.

The assumptions list records what is assumed, what is documented and what is still open: reference quantity, location, price level, index, type of building and share of external works. A short description of the method goes with it. Anyone who later has to explain why the figure came out as it did needs both.

What you can do now

1. Pick out two or three completed projects and take the costs per cost group of the first level from the final accounts.
2. Fix the reference quantity, for example the gross floor area, and work out the benchmark figure for each cost group. Note the price level and whether figures are gross or net.
3. Write down which assumptions an estimate for a new project would need, and mark what you are still missing.
4. If you hold a licence for collections of benchmark figures, clarify what you may use them for.