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 as a pass/fail. In our device session on the Android build, its stair function reported the layout and drew the stringer, but did not flag a riser or tread against a code limit, and its baluster function did not warn about wide openings. Its drawings carry a general note that you are responsible for a code-compliant design. CutOnce shows the IRC R311.7 riser and tread checks next to the numbers.

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.

Can I save calculations in either app?

BuildCalc saves the full results of its advanced functions under a name you choose and recalls them later. 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. 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 with streamlined keystrokes 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 2026-10-17

The short version

BuildCalc is a keypad construction calculator from 42nd Parallel with streamlined keystrokes and interactive stair, baluster, compound miter, and rafter functions with named save and recall. Its stair function draws the stringer, the stringer installation, and the finished staircase, and emails them as a PDF. 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 with streamlined keystrokes, and an input checklist on the advanced functions	Labeled forms; type each measurement into a named field
Feet-inch-fractions	Yes, plus metric	Yes, entered the way a tape reads, with a setting that runs the whole app in imperial or metric
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	No pass/fail against code limits; the drawings carry a general disclaimer	Riser, tread, total rise, and baluster opening checked against IRC defaults you can review and override in Settings
Balusters	Rail and stair baluster layout; results export as a data file	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, regular and irregular hip, and valley, with sheathing, purlin, backing, and plan angles, and a miter saw or protractor readout	Common, hip, valley, and jack, including irregular pitch, with sheathing, backing, and plan angles and hip drop
Materials	Masonry, drywall, footings, shingles, sheathing, and fence, with custom sizes and a room mode	Concrete, masonry, rebar, drywall, roofing, decking, paint, and fence, from your dimensions
Saving work	Named save and recall of advanced results	A tape that keeps 500 calculations, and inputs restored when you return to the app; no named saves yet
Output	Dimensioned stringer, installation, and finished staircase drawings by email as a PDF	Printable PDF plans with the layout drawn and every cut dimensioned
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 jobs and roof detail. BuildCalc lets you save the full results of an advanced function under a label and recall them later, which CutOnce does not do yet. Its roof functions report purlin angles, which CutOnce does not, and switch the cut angles between miter saw and protractor settings with one tap. Its material functions take as many custom brick, block, sheet, and shingle sizes as you store, and a room mode takes the drywall or masonry for walls and ceiling from one stored room. If your hands already know a keypad construction calculator, 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 stair and baluster functions report the geometry but leave the code check to you. 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 or protractor settings.

Get CutOnce if you want labeled inputs, stair and baluster layouts checked against code, 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 as a pass/fail. In our device session on the Android build, its stair function reported the layout and drew the stringer, but did not flag a riser or tread against a code limit, and its baluster function did not warn about wide openings. Its drawings carry a general note that you are responsible for a code-compliant design. CutOnce shows the IRC R311.7 riser and tread checks next to the numbers.
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.
Can I save calculations in either app?: BuildCalc saves the full results of its advanced functions under a name you choose and recalls them later. 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. 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.