Calculators
Calculate before the build does.
Six calculators for the questions before ground is broken — every figure sourced and dated, every result an honest range. And if you like, one click turns it into your BOB cost plan.
What will your build cost?
Construction cost calculator 2026
Construction cost range by floor area and finish level, plus a reserve recommendation. Excluding plot, outdoor works and ancillary costs. Sourced, updated 2026.
→The forgotten 15%
Ancillary cost calculator
Real estate transfer tax by federal state, notary, land registry, agent: every purchase-related cost for plot and new build — fully sourced.
→What will your renovation cost?
Renovation cost calculator
Costs for insulation, windows, roof, heat pump and full renovation as honest ranges — per measure, sourced and dated.
→Is this instalment okay?
Progress payment checker
Check a progress invoice against contract sum, change orders and § 650m BGB — the same logic as BOB’s payment guard. Developer instalments under the MaBV live in the app.
→How much house can you afford?
Affordability calculator
From net household income to maximum loan: rate, interest, repayment and equity — using the 35% rule of thumb and current interest levels.
→What does undrawn money cost?
Commitment interest calculator
Calculate what commitment interest costs you after the interest-free period — month by month, using the same engine as BOB’s funding view.
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