Sources and updates
Every figure that is not arithmetic, with its source, its date and its limits.
Every figure that is not arithmetic comes from somewhere. This page says where, when it was consulted, what exactly it backs up and what its limitations are. Where something could not be verified, that is stated too.
Unit definitions
These need no external verification because they are definitions, not measurements.
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| Figure | Source | Nature | Used in |
|---|---|---|---|
| Inch = 25.4 mm · foot = 0.3048 m · yard = 0.9144 m | International yard and pound agreement (1959) | Exact definition | All length and area conversions |
| Pound = 0.45359237 kg · ounce = 1/16 lb | International agreement (1959) | Exact definition | Ounces to grams, grams to ounces |
| US gallon = 231 in³ = 3.785411784 L | US definition | Exact definition | Paint, fluid ounces |
| Imperial fluid ounce = 28.4130625 ml | Imperial definition | Exact definition | Fluid ounces to ml |
| US legal cup = 240 ml | Nutrition labelling (FDA) | Regulatory definition | All cup conversions |
| BTU (International Table) = 1055.05585262 J | IT definition | Exact definition | BTU to kW, BTU to frigories, EER, SEER |
| Frigorie/h = 1 kcal/h = 1.163 W | Derived from 4186.8 J ÷ 3600 s | Exact calculation | All frigorie conversions |
| Ton of refrigeration = 12,000 BTU/h | US industry convention | Standardised convention | BTU to kW |
Ingredient densities
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| Source | What it backs | Where to check it | Reviewed | Status |
|---|---|---|---|---|
| King Arthur Baking, Ingredient Weight Chart | Solids and granulates: flours, sugars, cocoa, grains, nuts, seeds, leaveners, salts and dry dairy | kingarthurbaking.com | September 19, 2026 | Consulted |
| USDA FoodData Central | Dry lentils: weight per cup | fdc.nal.usda.gov | September 19, 2026 | Consulted |
| Codex Alimentarius standard for olive oils | Relative density of olive oil (0.910–0.916 at 20 °C) | fao.org | September 19, 2026 | Consulted |
| Reference physical densities | Water, milk, cream, yoghurt, honey and vegetable oils | Reference values at 20 °C, shown in every result | September 19, 2026 | Within the usual range |
One decision worth understanding
US recipe books round any liquid to 8 ounces per cup (227 g), which is its weight in ounces and not its real density. A cup of water weighs 236.6 g, not 227 g. DomusCalc uses the physical density, which is why its liquid figures do not match many American tables.
Stated limitations
- Dairy and oil densities vary with temperature and with the actual fat content of the product. The values used sit inside the usual range and are shown in the result so you can judge them.
- Couscous uses the cracked wheat value from the same source, on grain-size grounds. It is flagged as a borrowed figure and will be replaced if a better specific one appears.
Building materials
These values come from no standard. They are common-use figures that make a reasonable starting point, all editable and all written into the result.
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| Figure | Default | Nature | Used in |
|---|---|---|---|
| Paint coverage | 350 sq ft/gal · 10 m²/L | Usual for interior emulsion; the real figure is on the tin | Paint |
| Door area | 1.6 m² (80 × 200 cm leaf) | Standard size | Paint, wallpaper |
| Window area | 1.5 m² | Indicative average | Paint, wallpaper |
| Loose dry sand density | 1,500 kg/m³ (range 1,400–1,600) | Editable assumption | Sand |
| Loose gravel density | 1,550 kg/m³ (range 1,400–1,700) | Editable assumption | Gravel |
| Cement grout density | 1,600 kg/m³ | Usual for cement-based product | Grout |
| Plaster coverage | 0.9 kg/m²·mm (range 0.8–1.0) | The bag states it | Plaster |
| Brick or block joint | 10 mm | Common practice | Bricks, blocks, mortar |
| Tile joint | 2 mm | Common indoor practice | Tiles, grout |
| Sealant cartridge | 300 ml (formats from 280 to 310) | Most common format | Caulk |
| Waste | 5 – 15 % depending on the job | Widely shared trade judgement | Almost every home-improvement tool |
HVAC
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| Figure | Value | Nature | Used in |
|---|---|---|---|
| Specific load by volume | 30 / 40 / 50 W per m³ by insulation level | Usual range for dwellings | Cooling capacity, unit size |
| Climate factor | 0.85 / 1.00 / 1.15 | Proportional adjustment in the model | Unit size |
| Heat per person | 120 W (seated adult, light activity) | Usual order of magnitude | Unit size |
| Solar gain per m² of glazing | 60 (north) · 110 (south) · 150 (east/west) W/m² | Simplified design load | Unit size |
| Shading factors | 1.0 unshaded · 0.7 blind or curtain · 0.45 awning | Estimated reduction in radiation | Unit size |
| Safety margin | +10 % | The model's own criterion | Unit size |
| Commercial sizes | 6,000 to 60,000 BTU/h | Market steps | All capacity tools |
External resources
There is exactly one: the Bricolage Grotesque and Instrument Sans typefaces, which your browser requests from Google Fonts. No analytics, no libraries, no other call. The calculation happens entirely on your device.
What you will not find here
Because it could not be verified against a reliable source, or because it would have to be made up:
- Search volumes or traffic estimates.
- Specific material brands: the pack sizes quoted are standard market formats, not products.
- Material or electricity prices: you enter those.
- Ratings, reviews, user counts or testimonials. They do not exist and are not simulated.
Review schedule
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| Block | Last verified | How it is reviewed |
|---|---|---|
| Unit definitions | September 19, 2026 | They do not expire |
| Ingredients | September 19, 2026 | Re-consult the source table and regenerate the database |
| Building materials | September 19, 2026 | Check against data sheets from common manufacturers |
| HVAC | September 19, 2026 | Watch for changes in labelling rules (SEER2 and successors) |