# Harth free tools

> 33 free browser tools for architecture, BIM, construction quantities, site and solar studies, building performance and project documents. No signup, no upload: every calculation, IFC parse, image process and export runs locally in the browser. Calculators with dimensions default to imperial units and switch to metric.

Hub: https://harth.build/free-tools/
XML sitemap: https://harth.build/sitemap.xml

Each tool page is static HTML with the tool's method and formulas, a worked example in both unit systems, step-by-step instructions, reference sections and FAQs, so the content below can be read without running the tool. Results are estimates from the values a user enters; the tools do not look up codes, prices or climate data and make no compliance claims.

## Drawing & geometry

- [Free Drawing & Geometry Calculators](https://harth.build/free-tools/category/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.
- [Architectural scale calculator](https://harth.build/free-tools/architectural-scale-calculator/): Move between drawing and real dimensions, resize a print, and export a scale bar. Imperial or metric.
  - Imperial example: A 2 in line at 1:48 (¼″ = 1′-0″) represents 8 ft. At 1:96 (⅛″ = 1′-0″) it becomes 1 in, a 50% print resize, and a 120 × 80 ft plan fits an Arch D sheet at that scale.
  - Metric example: A 100 mm line at 1:100 represents 10 m. At 1:50 it becomes 200 mm, requiring a 200% print resize.
- [Roof pitch & roof area calculator](https://harth.build/free-tools/roof-pitch-calculator/): Convert roof pitch and total the sloping area and covering strips of your roof planes. Imperial or metric.
  - Imperial example: A 20 ft eave and 12 ft horizontal run at a 6:12 pitch form a 268.33 ft² sloping plane.
  - Metric example: A 6 m eave and 4 m horizontal run at 30° form a 27.71 m² sloping plane.
- [Ramp gradient calculator](https://harth.build/free-tools/ramp-gradient-calculator/): Convert rise and run to gradient, angle and sloping length. Imperial or metric.
  - Imperial example: A 30 in rise over 30 ft of horizontal run is a 1:12 gradient, 8.33% slope and 30.10 ft sloping length. At the ADA 30 in maximum rise per run it needs one run and no intermediate landing.
  - Metric example: A 0.5 m rise over 6 m horizontal run has a 1:12 gradient, 8.33% slope and 6.021 m sloping length.
- [Stair geometry calculator](https://harth.build/free-tools/stair-geometry-calculator/): Find straight-flight riser and tread options using your own design limits. Imperial or metric.
  - Imperial example: A 9 ft floor-to-floor height and 12.5 ft run can use 14 risers at 7.71 in and 13 goings at 11.54 in, within the 2021 IRC R311.7.5 limits of 7¾ in and 10 in.
  - Metric example: A 2.8 m floor height and 3.9 m run can use 15 risers at 186.67 mm and 14 goings at 278.57 mm.
- [Occupant load & egress worksheet](https://harth.build/free-tools/occupant-load-egress-worksheet/): Calculate occupant loads and width allowances using factors from your chosen code. Imperial or metric.
  - Imperial example: A 1,000 ft² space with a supplied 20 ft²/person factor gives 50 occupants. At 0.2 in/person, the width worksheet gives 10 in before any code minimums.
  - Metric example: A 100 m² space with a supplied 2 m²/person factor gives 50 occupants. At 5 mm/person, the width worksheet gives 250 mm before any code minimums.
- [Feet, inches & construction units](https://harth.build/free-tools/construction-unit-calculator/): Add mixed feet-and-inch lengths and convert length, area, volume and mass. Imperial or metric.
  - Example: 5′ 6½″ + 2′ 3¼″ = 7′ 9¾″, or 2.38125 m.
- [Floor & wall area calculator](https://harth.build/free-tools/floor-wall-area-calculator/): Total rectangular floor zones, wall faces and openings with a labelled plan. Imperial or metric.
  - Imperial example: A 16 × 12 ft room has 192 ft² of floor area and a 56 ft perimeter. At 8 ft height, walls total 448 ft² before openings; the ceiling is 192 ft² and trim runs 53 ft after a 3 ft door.
  - Metric example: A 5 × 4 m room has 20 m² floor area and 18 m perimeter. At 2.4 m height, walls total 43.2 m² before openings.

## BIM & files

- [Free BIM & IFC File Tools](https://harth.build/free-tools/category/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.
- [IFC viewer](https://harth.build/free-tools/ifc-viewer/): Open a local IFC model, orbit its geometry, isolate an element, and inspect its data.
  - Example: Load the bundled two-wall IFC4 sample to explore two elements and their dimensions.
- [IFC property inspector](https://harth.build/free-tools/ifc-property-inspector/): Search element classes, GlobalIds, property sets, quantities and project units.
  - Example: The sample wall has a named property set and a length quantity; search ‘Sample’ or its GlobalId.
- [IFC file health checker](https://harth.build/free-tools/ifc-file-health-checker/): Check STEP structure, references and duplicate IDs, then download the findings.
  - Example: The included valid sample should have no duplicate IDs or dangling references. A removed referenced record produces a finding.
- [IFC merge](https://harth.build/free-tools/ifc-merge/): Combine compatible IFC files into one project while remapping entity references.
  - Example: Merge the bundled sample and companion model to place three walls in one project.

## Materials & quantities

- [Free Material & Quantity Calculators](https://harth.build/free-tools/category/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.
- [Concrete quantity calculator](https://harth.build/free-tools/concrete-quantity-calculator/): Estimate slabs, walls, footings and columns, including waste and premix bags. Imperial or metric.
  - Imperial example: A 20 × 12 ft slab, 4 in thick, needs 2.96 yd³ net or 3.26 yd³ with 10% waste.
  - Metric example: A 6 × 4 m slab, 0.1 m thick, needs 2.4 m³ net or 2.64 m³ with 10% waste.
- [Brick & block quantity calculator](https://harth.build/free-tools/brick-block-calculator/): Estimate masonry units from wall area, openings, joints and waste. Imperial or metric.
  - Imperial example: A 240 ft² wall using a 16 × 8 in nominal block module needs 270 blocks before waste.
  - Metric example: A 10 m² wall using a 400 × 200 mm nominal block module needs 125 blocks before waste.
- [Tile quantity & layout calculator](https://harth.build/free-tools/tile-layout-calculator/): Compare an area allowance with a rectangular tile layout and box count. Imperial or metric.
  - Imperial example: A 12 × 10 ft room using 12 × 12 in tiles and no joints takes 120 tiles before waste.
  - Metric example: A 3 × 3 m room using 600 × 600 mm tiles and no joints takes 25 tiles before waste.
- [Plasterboard / drywall sheet calculator](https://harth.build/free-tools/drywall-sheet-calculator/): Compare sheet orientations and an area estimate for a rectangular wall. Imperial or metric.
  - Imperial example: A 16 × 8 ft wall fits four 4 × 8 ft sheets vertically before waste.
  - Metric example: A 4.8 × 2.4 m wall fits four 1.2 × 2.4 m sheets vertically before waste.
- [Paint quantity calculator](https://harth.build/free-tools/paint-quantity-calculator/): Calculate paint for walls and optional ceilings, including coats and tin sizes. Imperial or metric.
  - Imperial example: 448 ft² of surface, two coats and 350 ft²/gal coverage require 2.56 gal before allowance.
  - Metric example: A 6 × 4 × 2.4 m room has 48 m² of wall; two coats at 10 m²/L need 9.6 L before allowance.
- [Decking board calculator](https://harth.build/free-tools/decking-board-calculator/): Calculate board rows, linear metres and a conservative stock-length order. Imperial or metric.
  - Imperial example: A 12 ft wide deck with 5.5 in boards and ¼ in gaps needs 26 rows.
  - Metric example: A 3 m wide deck with 140 mm boards and 5 mm gaps needs 21 rows.
- [Fence material calculator](https://harth.build/free-tools/fence-material-calculator/): Build a material list for separate fence runs, panels or palings and gates. Imperial or metric.
  - Imperial example: A 40 ft run with no gate and 8 ft bays needs five bays and six posts. With two rails per bay, it needs ten rails.
  - Metric example: A 12 m run with no gate and 2.4 m bays needs five bays and six posts. With two rails per bay, it needs ten rails.
- [Excavation & bulk materials](https://harth.build/free-tools/excavation-bulk-material-calculator/): Estimate excavation or fill volume and material mass with explicit allowances. Imperial or metric.
  - Imperial example: A 30 × 10 ft area filled 4 in deep is 3.7 yd³ in place. A 1.2 loose-to-compacted multiplier means ordering 4.44 yd³.
  - Metric example: A 10 × 3 × 0.1 m fill layer is 3 m³ in place. A 1.2 loose-to-compacted multiplier means ordering 3.6 m³.
- [Steel & rebar weight calculator](https://harth.build/free-tools/steel-rebar-weight-calculator/): Calculate weights for round bars, plates, hollow sections and entered section masses. Imperial or metric.
  - Imperial example: A ½ in round bar at 490 lb/ft³ weighs approximately 0.668 lb/ft; ten 20 ft bars weigh 133.6 lb.
  - Metric example: A 12 mm round bar at 7,850 kg/m³ weighs approximately 0.888 kg/m; ten 6 m bars weigh 53.27 kg.
- [Insulation quantity calculator](https://harth.build/free-tools/insulation-quantity-calculator/): Calculate coverage and packs for batts or rolls with your waste allowance. Imperial or metric.
  - Imperial example: 1,000 ft² with one layer, 10% waste and 80 ft² per pack requires 14 packs.
  - Metric example: 100 m² with one layer, 10% waste and 8 m² per pack requires 14 packs.

## Site & solar

- [Free Site & Solar Tools](https://harth.build/free-tools/category/site-solar/): Check floor area ratio and site coverage, draw sun-path diagrams for any latitude, and size overhangs and shadows from sun angles.
- [Floor area ratio & site coverage](https://harth.build/free-tools/floor-area-ratio-calculator/): Calculate FAR and footprint coverage separately against your own planning limits. Imperial or metric.
  - Imperial example: A 60 × 100 ft site with two 2,400 ft² levels (4,800 ft² gross) and a 2,400 ft² footprint has FAR 0.8 and 40% coverage. Setbacks of 25 ft front, 5 ft each side and 15 ft rear leave a 50 × 60 ft, 3,000 ft² buildable envelope.
  - Metric example: A 600 m² site with 480 m² gross floor area and a 240 m² footprint has FAR 0.8 and 40% coverage.
- [Sun-path diagram generator](https://harth.build/free-tools/sun-path-diagram-generator/): Plot the sun for a selected day and both solstices; export SVG, PNG and hourly data.
  - Example: At the equator near the March equinox, the sun passes close to the zenith around solar noon.
- [Shadow length & overhang calculator](https://harth.build/free-tools/shadow-overhang-calculator/): Explore ground shadows and wall shading from entered sun angles and orientation. Imperial or metric.
  - Imperial example: At a 45° sun altitude, an 8 ft object casts an 8 ft ground shadow. A 2 ft overhang shades 2 ft down a directly facing wall.
  - Metric example: At a 45° sun altitude, a 3 m object casts a 3 m ground shadow. A 0.6 m overhang shades 0.6 m down a directly facing wall.

## Building performance

- [Free Building Performance Calculators](https://harth.build/free-tools/category/building-performance/): Convert R-values and U-values, compare envelope heat loss, compare embodied carbon using your EPD factors, and estimate solar PV yield.
- [R-value / U-value converter](https://harth.build/free-tools/r-value-u-value-converter/): Convert thermal resistance and transmittance with explicit SI and US units, or sum a layer stack with surface resistances. Imperial or metric.
  - Imperial example: R-20 h·ft²·°F/Btu corresponds to U-0.05 Btu/(h·ft²·°F) and approximately R-3.52 m²·K/W.
  - Metric example: R-3.5 m²·K/W corresponds to U-0.2857 W/(m²·K) and approximately R-19.87 in US units.
- [Envelope heat-loss comparison](https://harth.build/free-tools/envelope-heat-loss-comparison/): Compare two envelope schemes by steady-state heat loss, annual degree-day energy and heating cost. Imperial or metric.
  - Imperial example: 1,000 ft² at U = 0.05 Btu/(h·ft²·°F) and a 36 °F difference loses 1,800 Btu/h; with 6,000 °F·days, 90% efficiency and 1.50 per therm, the whole example Scheme A costs about 420 a year.
  - Metric example: 100 m² at U = 0.3 W/(m²·K) and a 20 K difference loses 600 W.
- [Material embodied-carbon comparison](https://harth.build/free-tools/embodied-carbon-comparison/): Compare material options using EPD factors or illustrative presets, per unit floor area, for A1–A3 or whole life. Imperial or metric.
  - Imperial example: 13 yd³ at a user-supplied 190 kg CO₂e/yd³ gives 2,470 kg CO₂e for the declared modules, or 2.47 kg CO₂e/ft² over 1,000 ft².
  - Metric example: 10 m³ at a user-supplied 250 kg CO₂e/m³ gives 2,500 kg CO₂e for the declared modules.
- [Solar PV yield estimator](https://harth.build/free-tools/solar-pv-yield-estimator/): Estimate annual and monthly PV output from capacity and a regional or documented specific yield, with savings and simple payback.
  - Example: A 5 kWp system at an assumed net yield of 1,200 kWh/kWp/year produces an estimated 6,000 kWh/year.

## Documents & presentation

- [Free Document & Presentation Builders](https://harth.build/free-tools/category/documents-presentation/): Build room schedules and area programs, design briefs, construction RFIs, rendering prompts and material mood boards, then export them.
- [Room schedule & area program](https://harth.build/free-tools/room-schedule-builder/): Build an editable room program with counts, areas and circulation allowance. Imperial or metric.
  - Imperial example: Four 200 ft² rooms give 800 ft² net. A 20% added circulation allowance gives 960 ft² total.
  - Metric example: Four 20 m² rooms give 80 m² net. A 20% added circulation allowance gives 96 m² total.
- [Architectural rendering prompt builder](https://harth.build/free-tools/architecture-rendering-prompt-builder/): Assemble a precise, editable rendering prompt from your design choices.
  - Example: A courtyard house in pale brick, viewed at eye level in soft morning light, can become a reusable rendering instruction.
- [Architectural design brief builder](https://harth.build/free-tools/architectural-design-brief-builder/): Turn project facts, priorities and constraints into a structured editable brief.
  - Example: A family house brief can list three bedrooms, accessible living, a budget and a desired completion date without inventing site facts.
- [Construction RFI form builder](https://harth.build/free-tools/construction-rfi-builder/): Prepare a clear request for information with drawing references and a response field.
  - Example: RFI-001 can reference drawing A-102 revision C and ask the design team to confirm a conflicting opening dimension.
- [Material palette & mood-board maker](https://harth.build/free-tools/material-palette-maker/): Arrange local images, name your materials and export a board with sampled colors.
  - Example: Combine timber, stone and textile photographs into a labelled three-material board with a color strip.

## Optional

- [Harth resource library](https://harth.build/resources/): building codes, zoning and design guides
- [Site llms.txt](https://harth.build/llms.txt): the rest of harth.build
- [Harth](https://harth.build/): the workspace these tools sit beside