Construction calculator for iPhone and Android
The construction calculator you pay for once.
Feet and inches with fractions, plus 100+ calculators for concrete, framing, roofing, stairs, drywall, tile, decks and more. Works with no signal. No account, no ads, no subscription.
- Every calculator free
- Pro: $24.99 one time
- Works offline
- English y español
No subscription
Pay once. Keep it.
Calculator apps moved to yearly subscriptions. Kerf didn't. Every calculator is free, and Pro is one $24.99 purchase that stays yours.
Math is never locked
Adding feet and inches, fractions, memory and the paper tape are free. So is every calculator.
No trial that bills you later
You see the price before you tap buy. Nothing renews, nothing to cancel.
No ads, free or Pro
No banners between you and the answer. Not now, not in the free version.
What you pay over time
| After | A $39.99 a year app | Kerf Pro |
|---|---|---|
| 1 year | $39.99 | $24.99 |
| 3 years | $119.97 | $24.99 |
| 5 years | $199.95 | $24.99 |
$39.99 a year is what some popular construction calculator apps charge today. Store prices can differ by country.
100+ calculators
A calculator for every trade on the job
Each one opens with real defaults, draws a dimensioned sketch from your numbers and lets you type the coverage straight off the bag or box.
Feet and inches calculator
Add, subtract, multiply and divide feet, inches and fractions down to 1/64. Backspace, memory and a paper tape you can read back.
Concrete and masonry
Slabs, footings, walls, columns and steps in yards and 40, 60 or 80 lb bags. Block, brick, mortar and rebar.
Framing
Wall and floor takeoffs, stud counts, opening framing with cut lengths, sheathing and board feet.
Roofing
Pitch, common and hip rafters, jack lengths, roof squares, bundles, underlayment, drip edge and vents.
Stairs with IRC checks
Risers, treads and stringer layout, checked against IRC riser height, tread depth and headroom.
Drywall, trim and paint
Sheets, mud, tape and screws. Baseboard, casing and crown miter angles. Gallons of paint and primer.
Flooring and tile
Boxes, tiles, thinset and grout, with waste for straight, diagonal and herringbone layouts.
Decks and fences
Deck boards, joists, posts and footings. Fence pickets, rails, posts and concrete per hole.
Landscape and sitework
Mulch, gravel, topsoil, pavers and base, retaining walls, sod and excavation in yards and tons.
Electrical
Wire size with voltage drop, circuit load, conduit fill and box fill, with the NEC table cited.
Plumbing
Drain slope, pipe volume, PEX coils and tank volume.
Level and pitch gauge
Use the phone as a level, inclinometer and roof pitch gauge, then send the pitch to the rafter calculator.
Code checks cite the rule they use. Your local building department has the final say.
Cut list optimizer
Know how many boards to buy before you leave for the yard
Enter the pieces you need and the stock length you buy. Kerf lays out every board, counts the blade kerf on each cut and shows the offcuts you keep.
- Counts the saw kerf, so two 48" pieces never come out of one 8' board
- Lengths in feet, inches and fractions, or metric
- A buy list you can text to the supplier
Free for up to 10 pieces from one stock length. Pro removes the limit and adds mixed stock lengths.
Jobs and estimates
From takeoff to a clean estimate
Save any result to a Job. Kerf builds the material list as you go, prices it from your own price book and turns it into a PDF estimate with your logo.
- Material lists build themselves from every calculator you save
- Your own unit prices, per supplier, used on every job
- Labor, markup, tax and terms on a PDF you can send from the truck
Jobs, estimates, PDF and the price book are part of Pro.
Built for the jobsite
Works in a basement. Speaks Spanish.
No signal needed
Everything runs on the phone. Crawl spaces, new subdivisions and steel buildings are fine.
No account
Open it and start working. Sign in is optional and only there to carry Pro between iPhone and Android.
English and Spanish in one app
Switch languages in settings. Your crew can run the same app in the language they think in.
Imperial first, metric too
Feet, inches and sixteenths by default, yards for concrete, and a metric switch when you need it.
Pricing
Free does the math. Pro runs the business.
Free
$0forever
- Every calculator, all 100+
- Feet and inches calculator with paper tape
- Level, inclinometer and pitch gauge
- Cut list up to 10 pieces
- Offline, no account, no ads
Pro
$24.99one time
- Unlimited Jobs with material lists
- Estimates and PDF with your logo
- Price book with your own unit prices
- Unlimited cut list, mixed stock lengths
- Backup, export and import
- Saved presets for the numbers you reuse
Pro is an in-app purchase on the App Store or Google Play. Price shown in US dollars.
Questions
What is actually free?
Every calculator, the feet and inches calculator, the level and pitch gauge, and the cut list up to 10 pieces. No ads and no account. You can use Kerf for years without paying.
What does Pro add, and is it really one payment?
Pro is $24.99 once, not a subscription. It adds unlimited Jobs, estimates and PDF, the price book, the full cut list with mixed stock lengths, backup and saved presets. Nothing renews.
If I buy on iPhone, do I get Pro on Android?
Apple and Google keep their purchases separate. If you want Pro on both, sign in with Apple or Google in the app and Pro follows your sign in. Restoring on a new phone of the same kind works without signing in.
Does it work without a signal?
Yes. Every calculator, the cut list, the level and your saved Jobs run on the phone. You only need a connection to buy Pro or restore a purchase.
Can I trust the numbers?
Formulas are tested against manufacturer charts, code tables and worked examples. Bag yields and coverage rates are editable, so you can type the number from the label you are holding. Results are estimates, so check critical work and let your building department decide on code questions.
Is Kerf in Spanish?
Yes. English and Spanish ship in the same app. Switch in settings, no second download.
Does it size beams, headers or joist spans?
Not yet. Span tables depend on species, grade and load, and we would rather leave them to your engineer or the code book than guess. Kerf counts and lays out the framing, it does not size it.
Put it in your pocket
Download Kerf free. Every calculator works the moment it opens.
Scan with your phone to download