Craft Quantities
Plan & Takeoffs

Reference data

The data these calculators run on

Every figure here is one this site’s calculators already compute with, published as a table you can read, cite and download — each row saying where it came from, and each table backed by the calculators that use it.
  • 3Reference tables
  • 93Rows, each with its source
  • CC BY 4.0Free to reuse, with credit

Only what the calculators use

A reference table here is a view onto the data behind the calculators, never a table assembled for its own sake. A row with no calculator behind it would have no verification behind it either, so it is not published.

Every row names its source

A standard, a manufacturer, trade practice or arithmetic — those carry different weight, and a bibliography at the bottom of a page flattens them into one claim. Where a property varies, the range is published rather than a single figure.

Free, and machine-readable

All of it is CC BY 4.0 and machine-readable at the same address, and every table downloads as CSV, Excel and PDF. Use it, build on it, and credit Craft Quantities.

The tables

Pick a table

3 tables · 93 rows · 217 calculators behind them

Electrical

Copper conductor sizes and ampacity

15 rows11 calculators compute with itArithmetic · Standard

Every copper conductor size this site computes with, in both systems, with the NEC ampacity beside it. AWG runs backwards and then turns over — 14 is thinner than 12, and above 1 the sizes are written 1/0 to 4/0 rather than 0 to −3 — which is the single commonest way a size is read wrong off a drawing. The area and diameter columns are not measurements: AWG is a defined geometric series, 36 AWG at 0.005 in and 4/0 at 0.46 in with a constant ratio across the 39 steps between them, so both follow by arithmetic from the gauge number alone.

Trade practice

Production rates by operation

68 rows156 calculators compute with itTrade practice

How long each operation takes one person, in person-hours per unit of work. Read the units before the numbers: every figure here is PERSON-hours, not crew-hours, so a two-person crew hanging fifty sheets in a day is 16 person-hours for 50 sheets rather than 8. Reading a crew-day as a person-day is the commonest way a labour figure comes out wrong, and it comes out wrong by the size of the crew.

Materials and physical properties

Bulk densities of construction materials

10 rows53 calculators compute with itTrade practice

What a cubic metre of loose material actually weighs, in both systems, as this site's calculators compute it. These are bulk densities — the weight of the material as it sits in a heap or a lorry, air gaps included — and not the density of the substance itself. A cubic metre of gravel is nowhere near the weight of a cubic metre of the rock it was crushed from, because roughly a third of it is the space between the stones.

Why this is free when the same data is not

Most organisations holding construction reference data either sell access to it or leave it inside a PDF nobody can link to a single row of. This site has no subscription to protect and nothing to upsell, so publishing the tables costs it nothing and makes the calculators above them checkable — which is the point.

What is deliberately absent

Several tables a reference library of this kind would normally carry — thermal conductivity by material, timber nominal-versus-actual by market, pipe wall thickness by schedule — are not published, because this site does not hold them: those calculators ask you for the figure rather than looking one up. Publishing a table the calculators do not use would be exactly the unverified data this library exists to avoid being.

Reference data

The documents behind the figures

The standards page lists every document the calculators cite, and the methodology pages set out how each result is worked.

Standards citedMethodology

  • A source on every row

    A standard, a manufacturer, trade practice or arithmetic — named where the figure is.

  • A range where reality is one

    A band prints whole, never flattened to a single figure.

  • Free to reuse

    CC BY 4.0, and the same rows as JSON. Credit Craft Quantities.

Frequently asked questions

Can I use these tables in my own work?
Yes. Everything here is published under CC BY 4.0: copy it, adapt it, use it commercially, and credit Craft Quantities. Each row's source travels with it, and it should stay with the figure wherever the figure goes.
Is there a machine-readable version?
Yes. Each table is at /api/v1/reference/ followed by the table's name and .json — the same rows the page prints, with each row's source and the calculators that compute with it. Every table page also downloads as CSV, Excel and PDF.
Why is there no table of thermal conductivity or timber sizes?
Because this site's calculators do not look those figures up — they ask you for them. A table here is published only when the calculators compute with it, and a table nothing computes with would be exactly the unverified data this library exists to avoid being.
Why are some values printed as a range?
Where a property really varies, one figure would be a fabrication however confidently it was printed. A band prints whole, with the usual figure in brackets where one can be defended, and the note under the row says what moves it within the band.