CalcBoard / For Engineers

Convert in One Panel, Calculate in the Next

The workflow engineering actually has — a conversion feeding a formula — without copying numbers between screens.

Download CalcBoard Free

Conversion and calculation are one task

Engineering arithmetic almost never starts in the units the formula wants. Pressure arrives in psi and the equation wants pascals; a flow rate is in gallons per minute and the model is metric; a datasheet is in BTU and the report is in kilowatts.

Every single-calculator app treats conversion as a detour: switch mode, convert, memorise, switch back, retype. CalcBoard puts the converter in one panel and the calculation in the next, both visible, with the Premium shared value tray moving results between them — up to 50 values, each labelled with the panel it came from.

Units that cover real work

79 units across 10 categories: length, mass, temperature, area, speed, time, data, volume, energy, and pressure. The factors are exact where the definitions are exact — an inch is 0.0254 m, a pound is 0.45359237 kg, a BTU is 1055.05585262 J — and the app carries conversions to 18 decimal places internally rather than rounding at display precision.

Pressure

PSI, bar, kPa, atm, mmHg, torr.

Energy

Joules, kWh, BTU, calories, eV.

Speed

m/s, km/h, mph, knots, ft/s.

Area

m², ft², hectares, acres.

Named variables instead of memory keys

A calculator with one memory register is a calculator you have to keep notes for. Define rho=1.225, cd=0.32, a=2.2 once, and use them by name in any panel and any mode, for as long as you keep them. They persist between sessions, so a project's constants stay put — more on how that works.

Exactly how precise, and where

Engineers care about this more than most users, so here is the specification rather than a slogan. Arithmetic and unit conversion — addition, subtraction, multiplication, division, powers, and every one of the 79 conversions — run on arbitrary-precision decimal numbers, carried to 15 decimal places on division and 18 on conversion. There is no floating-point drift, which is more than most calculators can say. Transcendental functions — sin, cos, tan, ln, log — are computed in double precision to roughly 15 significant digits, as in any calculator short of a symbolic algebra system.

Exact for dimensions, money, and conversions; conventionally accurate for trigonometry.

Free vs. Premium, honestly: the free app includes 2 panels, basic mode, 3 converter categories, and your last 10 history entries — no ads, no time limits. A one-time $2.99 purchase (no subscription) unlocks scientific and programmer modes, up to 8 panels, the shared value tray, all 10 converter categories, full history with search and CSV export, and all themes and button styles.

Frequently Asked Questions

How many units does CalcBoard convert?
79 units across 10 categories: length, mass, temperature, area, speed, time, data, volume, energy, and pressure. Length, mass, and temperature (13 units) are free; the rest come with the one-time $2.99 unlock.
Can I convert and calculate at the same time?
Yes — that is the core feature. Put the converter in one panel and a calculator in another, and move results between them with the shared value tray or a named variable.
Is the arithmetic exact?
Arithmetic and unit conversion use arbitrary-precision decimal, so there is no floating-point rounding error. Trigonometric and logarithmic functions are computed in double precision to about 15 significant digits.
Does it handle units inside expressions?
No. Conversion happens in the converter mode rather than in expressions — you cannot type '5 ft + 3 in' and get an answer. If unit-aware expressions are essential, a notepad calculator like Soulver is a better fit.
Does it do currency?
No. The converter covers physical and digital units only. There are no exchange rates in the app.

Convert and compute together

Up to 8 panels, 79 units, exact decimal arithmetic. Free to download.

Download Free on App Store

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