Is BuildCalc a subscription?

No. As of this writing BuildCalc is a paid app on both the App Store and Google Play, bought once up front. CutOnce is also not a subscription: it is a free download with a 7-day trial and a single purchase that unlocks everything permanently, with free updates.

Does BuildCalc check stairs against building code?

Not that its listings show. Its store listings and feature page describe the stair layout, the stringer drawings, and the baluster layout, but document no pass/fail check against a code limit. CutOnce shows the IRC R311.7 riser and tread checks next to the numbers and warns when a baluster opening exceeds your maximum.

Which is better for stairs?

For a code-checked layout from one total-rise measurement, CutOnce. For a keypad workflow with sub-riser and sub-tread inputs and a finished staircase drawing, BuildCalc. Both print a dimensioned stringer. Both lay out balusters, and each lets you choose where marks are measured from. BuildCalc offers three layout modes with marks at the leading edge, center, or trailing edge. CutOnce offers four modes, gives a mark for every baluster from the back of the tread, the nosing, or the riser face, warns when an opening exceeds your maximum, and prints a dimensioned PDF page. Its Spacing calculator also lays out marks along a sloped run.

Which app exports PDF plans?

BuildCalc documents PDF drawings for stairs only: the stringer layout, the stringer installation, and the finished staircase. CutOnce prints PDF plans in 13 calculators: stairs, rafters, hip and valley, rake walls, spacing, fencing, roofing, polygons, wall studs, box and frame miters, crown molding, masonry, and concrete.

Can I save calculations in either app?

BuildCalc saves labeled results, recalls them later, and emails or AirPrints them. CutOnce keeps a running tape of your last 500 calculations and restores your inputs when you come back to the app, but does not yet save named jobs.

Is BuildCalc available in Spanish?

Its App Store listing lists English only, and neither its Google Play listing nor its website mentions Spanish. CutOnce runs in English and Spanish, including its PDF plans.

Compare

CutOnce vs BuildCalc

Both are one-time purchases on iPhone and Android, and both print dimensioned stair drawings. BuildCalc keeps a calculator keypad that emulates Construction Master Pro and adds interactive advanced functions. CutOnce uses labeled forms and checks stairs and balusters against the IRC. Here is where each one is stronger.

Updated 2026-10-22

The short version

BuildCalc is a keypad construction calculator from 42nd Parallel that emulates Construction Master Pro and adds interactive stair, baluster, compound miter, diagonal, and hip and valley functions, with labeled save and recall. Its stair function draws the stringer, the stringer installation, and the finished staircase, and emails them as a PDF; stairs are the only PDF drawings it documents, while CutOnce prints PDF plans in 13 calculators. CutOnce solves the same stair, rafter, and feet-inch-fraction math from labeled input forms, derives the whole stair from one total-rise entry, and checks risers, treads, and baluster openings against IRC limits you can review and override. Pick BuildCalc if you want the keypad and saved jobs; pick CutOnce if you want code checks and forms.

Side by side

	BuildCalc	CutOnce
Entry model	Calculator keypad that emulates Construction Master Pro, and an input checklist on the advanced functions	Labeled forms; type each measurement into a named field
Feet-inch-fractions	Yes; metric too, switched by swiping the display	Yes, entered the way a tape reads, with one app-wide imperial or metric setting that carries entered values across a switch
Stairs	Basic and Advanced analysis, with riser, tread, sub-riser, and headroom inputs and a stringer throat result	Whole layout derived from one total-rise entry, with IRC R311.7 pass/fail shown inline
Stair code checks	Not documented in its store listings or on its website	Riser, tread, total rise, and baluster opening checked against IRC defaults you can review and override in Settings
Balusters	Limited-opening, evenly spaced, and on-center layouts, with marks at the leading edge, center, or trailing edge	Four layout modes, a warning when an opening exceeds your maximum, a choice of where marks are measured from, and a dimensioned PDF page
Rafters and roofs	Common rafters with height above plate (HAP) and D/3 and D/4 tests, and hip and valley with major and minor cheek, backing, plan, purlin, and sheathing angles, a jack cut list sorted longest or shortest first, and a miter saw or protractor readout	Common, hip, valley, and jack, including irregular hips, with sheathing, backing, and plan angles, cheek cuts, a jack schedule listed longest first, hip drop, and an optimized cut map, and its rafter and hip and valley PDF plans warn when a birdsmouth notch is deeper than a third of the rafter
Materials	Masonry with brick, block, tile, and pavers, drywall with a Room Mode, footings and slabs, shingles, sheathing, fence, and board feet through volume conversion, with custom sizes	Concrete, masonry, rebar, drywall, roofing, decking, paint, fence, and board feet, from your dimensions
Saving work	Saves and recalls labeled results, and emails or AirPrints them	A tape that keeps 500 calculations, and inputs restored when you return to the app; no named saves yet
Output	Dimensioned stringer layout, stringer installation, and finished staircase drawings, emailed as a PDF; stairs are the only PDF drawings it documents	Printable PDF plans in 13 calculators, with layouts drawn and measurements dimensioned: stairs, rafters, hip and valley, rake walls, spacing, fencing, roofing, polygons, wall studs, box and frame miters, crown molding, masonry, and concrete
Languages	English	English and Spanish
Pricing	Paid up front on both stores; no free trial listed	Free download with a 7-day trial, then a one-time purchase with free updates; free web calculators

Where BuildCalc is stronger

Saved results and roof detail. BuildCalc saves labeled results, recalls them later, and emails or AirPrints them; CutOnce has no saved jobs yet. Its roof functions report purlin angles, add a D/4 test to the D/3 test, let you sort the jack rafter cut list longest or shortest first, and give cut angles as miter saw or protractor settings. CutOnce has no purlin angles or D/4 test yet and lists jacks longest first only, though its rafter and hip and valley PDF plans warn when a birdsmouth notch is deeper than a third of the rafter. Its material functions keep custom brick, block, tile, paver, and sheet sizes, and a Room Mode works out drywall for a room. If your hands already know a Construction Master Pro keypad, BuildCalc is the shorter move.

Where CutOnce is different

CutOnce treats the building code as part of the answer. The stair calculator derives the layout from one total-rise measurement and marks each riser and tread limit pass or fail next to the number, and the baluster layout warns when an opening is wider than your maximum. BuildCalc's listings describe stair and baluster geometry but document no code check. CutOnce also prints PDF plans in 13 calculators, from stairs and rafters to fencing and concrete, where BuildCalc documents PDF drawings for stairs only. Every code value CutOnce uses can be reviewed and overridden in Settings for a local amendment. Inputs are labeled forms rather than key sequences, the app and its PDFs run in English or Spanish, and you can try it free for 7 days before you pay.

Which one should you get

Get BuildCalc if you want a keypad calculator without a subscription, need named saves of finished calculations, or cut roofs that call for purlin angles, a D/4 test, a shortest-first jack list, or protractor settings.

Get CutOnce if you want labeled inputs, stair and baluster layouts checked against code, baluster layouts in four modes with a mark for every baluster, measured from the point you choose and printed on a PDF page, Spacing marks along sloped runs, a Spanish-language app and PDFs, or a trial before you buy. The free web calculators below run the same math, so you can try the approach first.

Common questions

Is BuildCalc a subscription?: No. As of this writing BuildCalc is a paid app on both the App Store and Google Play, bought once up front. CutOnce is also not a subscription: it is a free download with a 7-day trial and a single purchase that unlocks everything permanently, with free updates.
Does BuildCalc check stairs against building code?: Not that its listings show. Its store listings and feature page describe the stair layout, the stringer drawings, and the baluster layout, but document no pass/fail check against a code limit. CutOnce shows the IRC R311.7 riser and tread checks next to the numbers and warns when a baluster opening exceeds your maximum.
Which is better for stairs?: For a code-checked layout from one total-rise measurement, CutOnce. For a keypad workflow with sub-riser and sub-tread inputs and a finished staircase drawing, BuildCalc. Both print a dimensioned stringer. Both lay out balusters, and each lets you choose where marks are measured from. BuildCalc offers three layout modes with marks at the leading edge, center, or trailing edge. CutOnce offers four modes, gives a mark for every baluster from the back of the tread, the nosing, or the riser face, warns when an opening exceeds your maximum, and prints a dimensioned PDF page. Its Spacing calculator also lays out marks along a sloped run.
Which app exports PDF plans?: BuildCalc documents PDF drawings for stairs only: the stringer layout, the stringer installation, and the finished staircase. CutOnce prints PDF plans in 13 calculators: stairs, rafters, hip and valley, rake walls, spacing, fencing, roofing, polygons, wall studs, box and frame miters, crown molding, masonry, and concrete.
Can I save calculations in either app?: BuildCalc saves labeled results, recalls them later, and emails or AirPrints them. CutOnce keeps a running tape of your last 500 calculations and restores your inputs when you come back to the app, but does not yet save named jobs.
Is BuildCalc available in Spanish?: Its App Store listing lists English only, and neither its Google Play listing nor its website mentions Spanish. CutOnce runs in English and Spanish, including its PDF plans.

Try the math before the app

The free web calculators run the same tested code as the app. If labeled forms and code-checked stairs suit you, the app adds the full toolbox and printable PDF plans.