JobCalc Help

JobCalc is a feet-inch-fraction construction calculator for iPhone. It replaces expensive subscription calculators with a single purchase — every feature included, nothing locked behind a paywall, and every future update free. No subscription, no in-app purchases, no paid upgrades. Ever.

Getting Started

JobCalc works like a standard calculator with trade-specific function keys. Enter numbers using the keypad, then tap a function to calculate.

Tip: Long-press any key for built-in help with a worked example, and a diagram for the main construction functions. Press Conv and the green second functions stand out (press it again to cancel); long-press a key then for help on its green function. Help is available in English and Spanish.

Calculators

Roofing & Framing

Pitch — enter in rise/12, degrees, percent grade, or slope ratio
Rise, Run, Diagonal — Pythagorean calculations for any right triangle
Hip/Valley rafter length, then press Hip/V again for the hip/valley cheek cut, jack cheek cut and hip/valley plumb cut (regular hips)
Jack rafter lengths — cycles through each jack on the hip or valley
Rake wall stud lengths

Stairs

Riser height, number of risers, tread width, stringer length, and inclination angle
Saved preferences for default riser height and tread width

Geometry

Circle and arc calculations — diameter, area, circumference, arc angle

Area & Volume

Area and volume in feet, yards, or meters

Materials

Concrete — volume in cubic yards for slabs, driveways, and columns, with a waste allowance
Board Feet — lumber board feet and cost per thousand board feet (MBM)
Weight — pounds, tons, metric tons and kilograms (press Weight again to step through them), including the weight of a volume of concrete
Cost — price any quantity: × the unit price, then Conv . gives the total in dollars

Unit Conversions

Tap the Conv key to convert between:

Feet, inches, yards, meters, centimeters, millimeters
Area and volume units
Enter fractions naturally (e.g. type 3/4 for three-quarter inch)

Memory

Use M+ and Conv M+ (M−) to accumulate running totals — useful for tallying board feet, material quantities, or dimensions across multiple entries. Memory keeps the total, average, and count, plus a paperless tape of your last 20 entries (Conv = or Rcl =).

FAQ

How do I see help for a key?

Press and hold any key. To get help on a green function, press Conv first. The help explains the key and shows a worked example of exactly what the display will read.

How do I clear everything?

Press On/C twice to clear the calculation. Press Conv then × (Clear All) to also reset stored values such as on-center spacing, riser height, and memory. Your preferences stay.

How do I change fractions or decimal places?

Tap the gear (top right) for Settings, or press Conv then % on the keypad for the calculator preferences.

Does JobCalc need the internet or an account?

No. Everything runs on your iPhone, and nothing is collected. See our privacy policy.

Is there a subscription?

No, and there never will be. You pay once and every future update is free, forever. There are no in-app purchases and no paid upgrades.

Need help?

Email info@payonce.dev and we'll get back to you, usually within two business days. Please include your iPhone model, your iOS version (Settings → General → About), and the keys you pressed, so we can reproduce the calculation.

Refunds are handled by Apple: visit reportaproblem.apple.com.