Best construction calculator apps

The feature matrix

Forty apps and tools, ten capabilities each, every claim checked against the developer's own store listing or documentation. This is the broadest side-by-side matrix we could assemble from first-party sources. Where a listing does not state a capability we say “Not documented” instead of guessing: an empty-looking cell means the developer never claimed the feature, not that we skipped checking.

The ten worth using

Ranked deep dives, equal depth for every app. Competitor cards are text only: their screenshots belong to their developers, so we link you to their listings instead of borrowing images.

1. 01

   CutOnce

   Ours · Top pick

   Best for form-based entry, code checks, and printed plans

   Our app, so weigh this entry accordingly. Every calculator is a labeled form: the stair calculator takes one total-rise measurement and returns the whole layout with IRC R311.7 riser and tread checks shown pass or fail, and rafters cover common, hip, valley, and jack including irregular pitch, with backing angles and hip drop. Results come back as dimensioned drawings, and PDF plans print from stairs, rafters, hip and valley, rake walls, spacing, fencing, polygon, and masonry. Imperial math runs in exact 64ths of an inch using integer arithmetic, entered the way a tape reads. The toolbox includes Fencing, Roofing Materials, Polygon, Trig, and Masonry. Version 1.17 added Polygon and expanded Roofing Materials. Version 1.12 added a dedicated trig mode with degree and degrees-minutes-seconds entry plus five memory registers. One-time purchase after a 7-day trial, English and Spanish, iOS and Android, no account.

   • +Labeled forms instead of keystroke sequences
   • +IRC R311.7 stair checks shown pass or fail
   • +Dimensioned drawings and printable PDF cut plans
   • +One-time purchase with free updates

   • −Imperial or metric per calculation is a settings choice
   • −No saved jobs, and no tile or excavation calculators
   • −Straight and deck stairs only, no L- or U-shaped layouts
   • −No laser-measure input

   Where it loses: there are no saved jobs, no tile or excavation calculators, and no L- or U-shaped stair layouts, laser-measure input is not supported, and you pick imperial or metric in settings rather than mixing both inside one calculation.

2. 02

   Construction Master Pro

   The standard

   Best if you already know the handheld

   Calculated Industries' app runs the same key sequences as the handheld Construction Master Pro and Pro Trig that have sat in gang boxes for decades, and its listing bundles both. Dimensional math in imperial and metric, stairs with riser limits and stairwell openings, rafters including regular and irregular hip, valley, and jacks with plumb, cheek, and level cut angles, full trig with degrees-minutes-seconds entry, board feet, and footing and block math. It saves and shares calculations and cut lists with the crew. Ask CMPro guidance, Bosch GLM laser input, and Project Notes round it out. Free download; the iOS listing offers a 14-day trial, then a subscription.

   • +Deepest keystroke-for-keystroke handheld emulation
   • +Regular and irregular hip, valley, and jack rafters
   • +Full trig with DMS entry
   • +Actively updated on both platforms
   • +Ask CMPro guidance, Bosch GLM laser input, and Project Notes

   • −Everything happens through calculator keystrokes
   • −Results read back one value at a time
   • −Full access after the trial is an auto-renewing subscription

   Where it loses: there is no drawn layout or printed plan, PDF export is not documented, Ask CMPro needs a connection while offline use of the calculators is not documented, and as of this writing full access after the trial is an auto-renewing subscription rather than a one-time purchase.

3. 03

   BuildCalc

   Power users

   Best one-time purchase for advanced stair options

   BuildCalc is where Construction Master users tend to land when they want off the subscription: it stays a single up-front purchase on both stores. It emulates the Construction Master keypad with a more modern interface, goes further on framing specifics with interactive stair, baluster, compound miter, diagonal, and hip and valley functions, switches between regular and irregular hip analysis, and draws dimensioned stringer, installation, and staircase diagrams you can email as a PDF. Swiping switches between imperial and metric, a trig display mode is included, and results save with labels. The iOS and Android builds both picked up new releases in 2026 after a quiet stretch.

   • +One-time purchase on iOS and Android
   • +Advanced stair options with dimensioned drawings
   • +Regular and irregular hip analysis
   • +PDF export of layout drawings

   • −Keeps the calculator-keypad entry model
   • −Documented PDFs are its stair drawings
   • −Stair code checks are not documented
   • −English only per its listings

   Where it loses: it keeps the calculator-keypad entry model, its documented PDFs are stair drawings, stair code checks are not documented, and its listings are English only.

4. 04

   Carpenter Tools - Calculator

   Closest new rival

   Best new form-based toolbox with scale drawings on Apple devices

   A new form-based toolbox for iPhone, iPad, and Mac that draws every answer to scale. It pairs a tape-style fraction keypad with framing, roof, site, finish, and trim tools, and checks stairs against common code limits. Metric and feet-inch-fraction entry are both listed. The core is free and a one-time Pro unlock covers the rest.

   • +To-scale drawing with every answer
   • +Tape-style fraction keypad
   • +Stairs checked against common code limits
   • +One-time Pro unlock rather than a subscription

   • −Apple platforms only
   • −Drawings share as images; PDF export is not documented
   • −Hip and valley detail, including irregular pitch and jacks, is not documented

   Where it loses: it is Apple-only, drawings share as pictures with PDF export not documented, offline use is not stated on its listing, and hip and valley detail is not documented.

5. 05

   Chippy Tools: Construction

   Forms-first rival

   Best forms-first toolbox for site work

   The closest competitor to CutOnce's entry model: Chippy Tools is a modern, forms-first toolbox from an Australian developer, with calculators for stairs, roof pitch, concrete slabs and post holes, decking, equal spacing, running measurements, and triangle trig. It supports millimeters through fractional inches, switches between metric and imperial instantly, states plainly that it works offline, and shows no ads. It requires an in-app account sign-in with an emailed code. The free tier includes the baluster spacing calculator; the rest sits behind a Pro unlock sold as a subscription or a comparatively steep lifetime purchase.

   • +Modern forms-first entry like a checklist, not a keypad
   • +Metric and imperial switch instantly
   • +Documented offline support, no ads
   • +Strong site-work coverage: spacing, levels, soil, asphalt

   • −No rafter calculator in the listed toolset
   • −No board feet
   • −Pro unlock is subscription-first
   • −Requires an in-app account sign-in

   Where it loses: there is no rafter calculator in its listed toolset and no board-feet math, so framers still need a second app, an account sign-in is required before use, and most of the toolbox sits behind a subscription-first Pro unlock.

6. 06

   Construction Calculator: Pro²

   Stair shapes

   Best for L, U, and spiral stair shapes on iPhone

   A form-based calculator for iPhone that lays out straight, L, U, and spiral stairs in plan and elevation views, with feet-inch-fraction math in a Quick Calc, saved and named calculations, and 44 languages. It works offline and exports PNG and PDF. Individual calculators unlock separately, or a subscription opens them all.

   • +Straight, L, U, and spiral stairs with plan and elevation views
   • +Saved and named calculations
   • +Documented offline use, with PNG and PDF export
   • +44 languages

   • −iPhone only
   • −Per-calculator unlocks or a subscription
   • −Code checks beyond a comfort check, hip and valley, and trig are not documented

   Where it loses: it is iPhone-only, full access is per-calculator unlocks or a subscription, and its listing documents a comfort check rather than code limits, with hip and valley and trig math not documented.

7. 07

   Construction Calculator (xNeat)

   iOS · Feet-inch

   Best lightweight feet-inch keypad on iOS

   A focused feet-inch-fraction calculator for iPhone that converts between all the building formats: feet-inch-fractions, inch fractions, yards, decimal feet and inches, and metric. As a plain tape-math keypad it is quick and unfussy, which is what a lot of finish carpenters actually want on the jobsite. The catch is the upgrade path: stairs, common rafters, and hip and valley rafters are each sold as separate paid add-ons on top of a premium tier, so the sticker price of the full toolbox is easy to underestimate.

   • +Clean, fast feet-inch-fraction math
   • +Converts across every building dimension format
   • +Free to start

   • −iOS only
   • −Stairs and rafters cost extra as add-ons
   • −Listing documents little beyond the core calculator

   Where it loses: it is iOS-only, the stair and rafter calculators are separate paid add-ons rather than part of the app, and its listing leaves board feet, concrete, trig, PDF, and offline support undocumented.

8. 08

   Construction Calculator A1

   Estimator

   Best material estimator and BOQ generator

   A1 is a different kind of tool from the framing calculators above: a materials and quantities estimator aimed at civil work, with concrete for slabs, beams, columns, footings, staircases, and retaining walls, roofing area and pitch with rafter lengths for gable and flat roofs, brickwork, steel shapes, and excavation, plus feet-inch-fraction entry with a running tape. It exports branded PDF and Excel reports, works offline, and syncs to a web version. The free tier caps you at five calculations a day; a Pro unlock or a separate Pro app on Android removes the caps and ads.

   • +Widest material and BOQ coverage on this list
   • +PDF and Excel reports with your logo
   • +Phone, tablet, watch, and web
   • +Documented offline support

   • −Estimating depth, not cut-layout depth
   • −Free tier caps daily calculations
   • −No stringer or hip-valley cut layouts

   Where it loses: it estimates quantities rather than laying out cuts, so there are no stringer diagrams or hip and valley cut angles, and the free tier's daily calculation cap makes the paid unlock close to mandatory for real use.

9. 09

   Concrete Calc Pro

   Concrete specialist

   Best dedicated concrete calculator

   Calculated Industries' concrete specialist, and the strongest single-trade pick in the matrix. It covers slabs, footings, columns, and walls in feet-inch-fraction, yards, or metric, converts between cubic yards, feet, and meters instantly, figures loads, truckloads, and bag counts, and covers what general apps leave out: rebar spacing, sizing, quantities, linear feet, and weight. It even lays out code-aware concrete stairs. Like the rest of the current Calculated Industries line, full access after the free trial is a subscription.

   • +Deepest rebar support of any app here
   • +Loads, truckloads, and bag counts
   • +Code-aware concrete stair layouts
   • +Feet-inch-fraction and metric

   • −Concrete scope only
   • −Subscription after the trial
   • −DMS conversion but no full trig

   Where it loses: it is concrete-only by design, so framers need a second app, its trig stops at degrees-minutes-seconds conversion, and full access is a subscription as of this writing.

10. 10

    Blocklayer.com

    Free · Web

    Best pick straight from the browser

    Blocklayer has been the free answer for years, even though app roundups rarely mention it. It is a sprawling website of interactive construction calculators: straight and spiral stairs, hip, gable, gambrel, and saltbox roofs, concrete slabs with rebar spacing and premix bags, framing, decks, fencing, and printable templates for protractors, arcs, and rafter cuts, all with diagrams and an imperial-metric toggle. For one-off math at a desk it is excellent, and it costs nothing. It is also a fair benchmark: if an app charges a subscription for math this site does free, the app needs a better reason than the math.

    • +Free, no install, no account
    • +Unusually broad calculator coverage with diagrams
    • +Printable templates for real layout work
    • +Imperial and metric throughout

    • −Needs a browser and a connection
    • −Desktop-era interface on a phone
    • −No saved projects or code checks

    Where it loses: it needs a signal and a browser, the interface predates modern phones, and nothing checks your stairs against code or hands you a dimensioned cut plan at the saw.

Best pick by trade

Framer

CutOnce for drawn layouts and irregular hip and valley math; Construction Master Pro if your hands already know the keystrokes.

Roofer

CutOnce or Construction Master Pro for rafter math; RedX Roof, now in the matrix, if you want full 3D roof modeling.

Concrete

Concrete Calc Pro for rebar depth; Construction Calculator A1 if you also estimate quantities and costs.

Deck and stair builders

CutOnce for IRC-checked stringers from one rise; BuildCalc for its advanced stair options on a keypad; StringerPro for single-purpose code-checked stringers and Pro² for L, U, and spiral shapes.

DIY

Blocklayer.com or the free web calculators below before installing anything; RedX Construction Calculator for a free keystroke calculator, or Construction Calculator Lite on Android, free with ads, for feet-inch math plus concrete and triangle modules.

Prefer a browser tool?

Most searches for construction math actually land on free web calculators. If a browser tab fits how you work better than an app does, these are the ones worth bookmarking. Our own free web calculators run the CutOnce app's tested stair, rafter, and tape-math code with no install and no sign-up.

• Inch Calculator

  Huge library of clearly explained construction and conversion calculators.

• Omni Calculator, Construction

  Hundreds of construction calculators with formulas shown.

• MyCarpentry

  Carpentry-focused calculators alongside plans and how-tos.

• SBE Builders

  Free deep roof-framing geometry from a working framer.

• Concrete Network

  Concrete volume tools plus contractor-grade pours and finishes guidance.

• Blocklayer.com

  The broadest of the web tools; covered in the matrix above.