A little less working out.
A little more making.

Free online tools for architects, designers and builders

Harth's free tools cover the small calculations and file jobs that interrupt design and construction work: converting a drawing scale, checking a stair, estimating concrete or paint, reading an IFC model, plotting the sun or drafting an RFI. Each tool opens with a worked example, shows its formula and assumptions, and exports a PDF, CSV, SVG or file you can keep.

Nothing needs installing and nothing is uploaded. The tools run in your browser, so they also work on client and site data you cannot share with a cloud service.

Drawing & geometry

Convert drawing scales, add feet and inches, and work out roof pitch, ramp gradients, stair risers and treads, floor and wall areas, and occupant loads.

Start with: Architectural scale calculator, Roof pitch & roof area calculator, Stair geometry calculator, or see all 7 drawing & geometry tools.

BIM & files

Open, inspect, check and merge IFC models in the browser: orbit and section a model, search its property sets and quantities, validate its structure, and combine compatible files. Files are parsed locally and never uploaded.

Start with: IFC viewer, IFC property inspector, IFC file health checker, or see all 4 bim & files tools.

Materials & quantities

Estimate concrete, brick and block, tile, drywall, paint, decking, fencing, excavation and fill, steel and rebar weight, and insulation, with explicit waste allowances.

Start with: Concrete quantity calculator, Tile quantity & layout calculator, Paint quantity calculator, or see all 10 materials & quantities tools.

Site & solar

Check floor area ratio and site coverage, draw sun-path diagrams for any latitude, and size overhangs and shadows from sun angles.

Start with: Floor area ratio & site coverage, Sun-path diagram generator, Shadow length & overhang calculator, or see all 3 site & solar tools.

Building performance

Convert R-values and U-values, compare envelope heat loss, compare embodied carbon using your EPD factors, and estimate solar PV yield.

Start with: R-value / U-value converter, Envelope heat-loss comparison, Solar PV yield estimator, or see all 4 building performance tools.

Documents & presentation

Build room schedules and area programs, design briefs, construction RFIs, rendering prompts and material mood boards, then export them.

Start with: Room schedule & area program, Construction RFI form builder, Material palette & mood-board maker, or see all 5 documents & presentation tools.

Frequently asked questions