About the project
Existing online calculators typically hand you a bare number with no context: they don't show how they got there, they don't warn you when an input makes no sense, and they only handle regular rectangles. On a building site that doesn't help — floor plans are rarely regular, and ordering the wrong quantity of material costs money.
Koliko treba covers 53 calculations across fifteen areas: concrete and foundations, masonry, roofs and stairs, sheet metal and drainage, heating, tiling and flooring, finishing work, fences, metal and general-purpose tools.
What we built
Alongside the result, every calculator draws a scale technical diagram with dimensions and checks whether the input falls within usual limits — it flags when joist spacing is too wide for that board thickness, or when a staircase falls outside Blondel's formula.
The area calculators accept irregular floor plans as well: L and U shapes, trapezoids, circles and circular segments, entry by vertex coordinates, or a walk-around measurement along the walls, where the tool itself verifies whether your measurements close back to the starting point.
- 53 calculators, each pairing the result with a scale drawing
- Input validation that explains why a value falls outside the limits
- Support for irregular floor plans and walk-around measuring
- Works without an internet connection after the first visit (PWA)
- Clean printout with measurements and drawing, plus copy-to-clipboard results for quotes
Why this matters for your project
If your business depends on a calculation, a configurator, or a quote customers assemble themselves, this project shows how complex logic becomes a tool users grasp immediately — with a visual check instead of a bare number, working even in the field with no signal.