What your readers can do with it
Anyone who has added 12' 7-3/8" to 9' 10-5/8" on a phone calculator knows the problem: the phone wants decimals and the tape measure reads in sixteenths. The construction calculator takes lengths the way people say them, Feet, Inch and a fraction, and answers to the nearest 1/16 inch unless the reader picks another fraction.
- Keypad: add, subtract, multiply and divide lengths, square and cube them for areas and volumes, and convert to metres or decimal feet. Every entry lands on a paper-style tape.
- Triangle and pitch: any two of rise, run, diagonal and pitch give the other two, with the plumb and level cut angles.
- Stairs: risers, treads, stringer length and a check against IRC R311.7 or England's Approved Document K.
- Roof framing: common rafter, hip or valley, a jack rafter cut list and the roof area in squares.
Where it fits
A deck or stair building guide is the obvious home: readers enter their own floor-to-floor height instead of copying your example. Lumber yards and remodelling firms can add it to a "plan your project" page, and carpentry instructors can put it on a course site so apprentices check their fraction arithmetic before they cut.
Suggested size
The default frame is 780 px high and up to 960 px wide, which fits the keypad tab with its tape. The Stairs and Roof framing tabs list far more: the full stair result with its code checks runs to about 1,770 px at that width. If your page is about stairs or roofs, set the height to 1,200 px or more so the main results show without scrolling inside the frame. On a phone the keypad fits in about 1,050 px.
Open it on a stair problem
A link can choose the tab and fill it in. This one lays out a stair with a 9 ft rise, a 7-1/2 inch target riser and 10 inch treads, checked against the IRC:
https://widemath.com/embed/construction-calculator/?tab=stairs&code=irc&rise=9%20ft%200%20in&target=7-1/2%20in&tread=10%20in
The widget answers 14 risers of 7-11/16" and 13 treads of 10", a total run of 10' 10", and shows that the layout passes the IRC riser and tread checks. The stair result is long, so raise the frame to about 1,200 px when you use this link.
Add it in three steps
- Set the height for the tab your page is about, then press Copy embed code.
- Paste the code into a Custom HTML block (WordPress), an Embed HTML element (Wix) or a Code block (Squarespace).
- Check the preview on a phone: tradespeople often read on one at the job site.
Frequently asked questions
Is it a Construction Master calculator?
It is a Construction Master style calculator: an independent design by WideMath that follows the same key sequences, such as 5 Feet 3 Inch 1 / 2 for 5' 3-1/2". WideMath is not affiliated with Calculated Industries.
Does it work in metric?
Yes. Metres, centimetres and millimetres work on the keypad and in every form, and the stair tab can check a metric stair against Approved Document K for England.
Can readers rely on the code check?
It covers the riser, tread and related rules it lists, not handrails, guards or stair width, and the widget says so. Readers should still check their local building code and use a qualified builder for structural work.
More calculator widgets
Want the explanations and worked examples as well? They are on the full Construction Calculator page. All 24 widgets, each with a Copy code button, are in the calculator widget gallery.
Unit Converter
19 engineering quantities, every unit at once, and a free-form box for compound units.
Moment of Inertia Calculator
Centroid, Ix, Iy and section moduli for 11 shapes or built-up sections, with the working table.
Scientific Calculator
A Casio-style keypad with exact fractions and eight modes, narrow enough for a sidebar.