Sources
Three kinds of number go into these planners, and they are not equally solid. This page says which is which.
1. Exact by definition
Unit conversions. An inch is exactly 25.4 mm and a foot is exactly 0.3048 m, both fixed by international agreement in 1959. Every calculation on this site is done in metres and converted at the edges, so switching between feet and metres never changes an answer.
2. Published standards
Real documents, published by bodies that can be cited. Only three figures on this site come from one.
| Figure | Where it comes from | Used by |
|---|---|---|
| VESA mounting hole patterns — 75×75, 100×100, 200×100, 200×200, 400×200, 400×400 mm | The Flat Display Mounting Interface, published by VESA | Monitor arm |
| 32 in minimum clear width for an accessible doorway | 2010 ADA Standards, section 404.2.3 | Through a door |
| 32 in clear width and 78 in clear height for a home's required exit door | International Residential Code, section R311.2 | Through a door |
3. Trade conventions
Numbers the relevant trade quotes, repeats and mostly agrees on, with no single body behind them. They are reasonable starting points and they are not rules. Every one of them is a field you can change.
| Convention | What it rests on | Used by |
|---|---|---|
| 24 in to pull a dining chair out, 36 in to walk behind a seated person, 44 in to serve past one | Widely repeated kitchen and dining design guidance. No single publisher. | Dining table |
| 24 to 30 in of table edge per person | The same body of guidance. The range is the honest form of it. | Dining table |
| US mattress sizes: twin 38×75, twin XL 38×80, full 54×75, queen 60×80, king 76×80, California king 72×84 in | An industry convention, not a standard issued by any authority. Makers vary by an inch either way. | Bed size |
| About 30 in to walk at the side of a bed, 36 in at the foot | Residential layout guidance. The 36 in figure for a main walking route is the most consistently quoted number in the whole set. | Bed size, Murphy bed |
| Room needed for a pool table = playing surface + two cue lengths on each axis | The chart every table maker publishes, in the same form. A standard two-piece cue is 58 in; shorter ones are sold at 52, 48, 42 and 36 in. | Pool table |
| Playing surfaces: 7 ft table 39×78, 8 ft 44×88, 8½ ft 46×92, 9 ft 50×100 in | The sizes the trade builds to. Individual makers differ slightly, which is why the custom fields are there. | Pool table |
| Operating and safety space around gym equipment | Manufacturer manuals, which disagree with each other. Treadmill run-off in particular is a safety figure your own manual will state. | Home gym |
4. One maker's published figures
Wall bed cabinet depths and floor projections vary far too much to average. The defaults on the Murphy bed planner are taken from Bedderway's published dimensions — a vertical queen at 65 in wide, 87¾ in tall and 16⅝ in deep closed, projecting 86⅞ in when down. They are one manufacturer's numbers, shown as a starting point. Use your own model's spec sheet.
What you can change
Everything in sections 3 and 4. No planner here hard-codes a clearance as a requirement, because there is no requirement to hard-code. Each tool shows the figure it is using, in a field, next to a note saying what the number buys you. Change it and the answer moves while you watch.
The two code figures in section 2 are stated as facts about the code, not applied as constraints. The planner will happily tell you a 28 inch door works, because in a house it usually does.
What is not here
No figure on this site was invented to fill a gap. Where a number could not be verified, the page says so in words rather than printing a confident value — the headroom a wall bed needs above its cabinet is the clearest example, quoted as a range because makers quote a range.
The methodology page covers how the geometry itself works and what these plans do not model. If a figure here looks wrong to you, say so and say what you use instead.