The calc engine, in your browser

Your arithmetic, on the record.

The Calculation Canvas is a live worksheet with units. You write the calc the way you would on paper, the engine checks the units on every line and converts to the pay unit, and the finished sheet files with the quantity it supports. This page runs the same engine.

The calc engine at work

Each line is an equation; each result carries its unit and the conversion it used, and the reference library is one click from any calc box. Captured and calculated in the field on a tablet or phone, and open on your computer when it needs refining.

A site photograph of a formed concrete face in the markup editor: three areas shaded and labelled A1, A2 and A3, each dimensioned in inches, an inset close-up joined by a leader, and a calc box on the photo that computes A1 = 1.91 sy, A2 = 0.18 sy and A3 = 0.92 sy from those dimensions and totals 4.01 cubic yards, with a measured-by / calculated-by / checked-by block beneath. — The programA quantity worked on the photo.Three areas shaded and dimensioned on the photo, and the calc box beside them turning those dimensions into square yards and then cubic yards — each line an equation, each result with its unit and the conversion it used. Measured by, calculated by and checked by sit on the same page.

Three calc boxes: ASTM A615 nominal properties for a #4 bar and a #10 bar (diameter, area and weight per foot), a bar weight of 2182.25 lb from a length, a count and the unit weight, and a spiral rebar worksheet that takes height, pitch, core diameter and end turns through body turns, circumference and helix length per turn to a length of 616.53 ft and a weight of 411.84 lb, with its references cited at the foot. — The programFull equations, with their sources.A spiral bar taken from height, pitch and core diameter to its length and weight, one named step per line, beside the bar properties it draws on. The worksheet cites where its method comes from.

The reference library dialog: on the left, groups for rebar and steel, geometry (rectangle, triangle, Heron, trapezoid, irregular quadrilateral, Bretschneider, area by coordinates, circle, circular segment), earthwork volumes (average end area, prismoidal), helical rebar and concrete; on the right, the ASTM A615 table of nominal diameter, area and weight per foot for bar sizes #3 through #18. — The programThe reference library.Civil formulas and quantities already in the program: bar properties by size, areas from a rectangle to a traverse by coordinates, average-end-area and prismoidal volumes, spiral rebar, concrete. Pick one and it drops into the calc box as lines you can read and change.

A calc box: a drilled shaft volume from a 30 ft length and a 36 inch diameter, 7.85 cubic yards; a mud slab of 70 by 98 by 6 inches, 0.88 cubic yards; their total 8.74; and under a clouded heading "Yield Check" the total required for two, 17.47 cubic yards, against 27 delivered, a yield of 1.55. — The programA yield check.A shaft as a cylinder in feet and inches, a slab in inches, both converted to cubic yards by the engine — then the yield against what was delivered, clouded for the checker.

Units ride along

Feet, inches, yards, pounds, tons, square and cubic units, and the pay units your contract uses. Add feet to inches and the engine converts; add feet to pounds and it refuses that line.

Every step stays visible

A worksheet is a list of lines, each one a named value or a result. The checker reads it top to bottom, the way a hand calc is read, with nothing hidden in a cell formula.

Conversions are recorded, not assumed

When a result is converted to the pay unit, the factor the engine actually applied is printed under the line. A quantity is never a number without its unit.

It lives on the record

Inside a project the worksheet is a Calculation Canvas: it references plan sheets, embeds on markups, and forks a copy into the submittal package so the quantity and its arithmetic are filed together.

Three worksheets, evaluated by the engine on this page

These results are not typed in. The same engine that runs inside a project computed them when this page rendered.

Structure excavation, paid by the cubic yard

Field dimensions go in feet. The engine carries the units through the arithmetic and converts the result to the pay unit on request.

L := 120 ftsta 12+00 to 13+20

L = 120 ft

w := 4 fttrench width

w = 4 ft

d := 5.5 ftaverage depth

d = 5.5 ft

V := L * w * d

V = 2640 ft^3

V to CY =

97.78 CY= 2640 ft^3 × (1 CY / 27 ft^3) = 97.78 CY

Reinforcing bars, paid by the pound

A count, a length and a unit weight. Every step is on the sheet, so the checker sees where the number came from.

n := 24#4 bars

n = 24

L := 20 fteach

L = 20 ft

w := 0.668 lb/ft#4 unit weight

w = 0.67 lb / ft

W := n * L * w

W = 320.64 lb

Mixed units are added correctly, or refused

Feet plus inches is fine. Feet plus pounds is an error on that line, and the rest of the sheet keeps evaluating.

2 ft + 12 in =

3 ft

1 CY to ft^3 =

27 ft^3= 1 CY × (27 ft^3 / 1 CY) = 27 ft^3

3 ft + 2 lb =

Units do not match

5 + 5 =

10

Try it with your own numbers

Change a dimension, add a line, convert to a different pay unit. What you type stays in your browser.

Try the worksheet yourself

Your name and work email unlock the live worksheet on this browser. No account, no card. We will follow up once by email.

A worksheet for a structure excavation: length 120 ft, width 4 ft, depth 5.5 ft, the volume 2640 cubic feet, and its conversion to 97.78 cubic yards with the factor printed under the line. — The programWritten the way it is on paper. The engine carries the units through every line and prints the factor it used to reach the pay unit.

Inside a project, the worksheet is part of the record

It references the plan sheet, sits on the markup, and forks into the submittal package with the pay item it supports.

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