Dozenal Calc
A calculator in base twelve
Free
A "dozenal calculator" with a novel notation for numbers.
A "dozenal calculator" — a scientific calculator that computes not in tens, but in twelves. With its own symbols for the digits.
What base 12 can do that base 10 can't
In the decimal system, 1/3 is an infinite repeating fraction (0.333…). In base 12 it's short and exact: 0.4. Sixths, ninths, and every fraction whose denominator is built from twos and threes also become finite in dozenal. No coincidence: twelve has six divisors, ten only four.
Dozenal Calc computes exactly — a rational track runs in parallel with floating-point arithmetic. Repeating fractions appear with a bar over the recurring digits, for example 1/7 as 0.186A3 with a repetend bar.
Features
• Basic arithmetic, parentheses, signs
• Power, square root, nth root, logarithm to any base
• Trigonometric and hyperbolic functions including their inverses
• Constants π, e, φ, √2; factorial, absolute value, reciprocal, modulo
• Parallel addition (a⊕b) for resistor circuits
• Memory (STO/RCL/MC) with exact rational preservation
• Angle modes DEG / RAD / GRAD
• Numeral-system switch (base 12/10) in the settings — input AND result, applies to both calculators
• Light and dark theme
Unit converter
One swipe to the left opens the second calculator: it converts imperial and metric units into one another — length, area, volume, weight, time, angle, money (£/sh/d), temperature and more. Compound entries like 3 ft 5 in, breakdown into part units, and math right inside the entry (× ÷ ⊕ ^ √ log) with memory and constants. Results travel between the two calculators at the press of a key. A color code keeps the worlds apart: green for the world of ten (metric, base 10), violet for the world of twelve (imperial, base 12).
Hands-on theory — now with pictures
A richly illustrated read explains why twelve in particular is a special number, in three blocks:
• Twelve and the World — from the dodecagon and dodecahedron through pyrite, garnet, viruses and quasicrystals to music, art, architecture and calendars
• Dozenal Mathematics — divisors and periods, the number bases compared, a history of place-value systems
• Dozenal Society — the movement for twelve, new digits for ten and eleven, the TGM measurement system and related dozenal calculators
Many chapters show public-domain historical illustrations — from Haüy's pyrite plate through Leonardo's dodecahedron to Vermeer's balance — each with a tappable source citation. Plus a dedicated unit theory on measure and number, two illustrated operating manuals for both calculators, and recommendations for dozenal-friendly calculators on every platform.
Fourteen languages
Deutsch, English, Français, Español, Italiano, فارسی, Русский, Gaeilge, हिन्दी, 简体中文, 繁體中文, Cymraeg, 日本語, العربية — freely selectable in the info menu.
What Dozenal Calc doesn't do
• No ads, no tracking, no analytics
• No internet connection, no permissions
• No personal data
The app works completely offline. What you type stays on your device.
Who is it for?
For teachers who want to show how a different number system transforms everyday work with fractions — and for anyone who wants to see mathematics from an unfamiliar perspective.
License: MIT. Contact: dozenal@weltanschauung.app
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
New in 1.5.1:
• The unit converter is now the calculator's second page — just swipe left. Results travel between the two calculators at the press of a key.
• Do math right inside the converter: × ÷ ⊕ ^ √ log, with memory and constants.
• Color code: green for the world of ten (metric, base 10), violet for the world of twelve (imperial, base 12).
• Two illustrated manuals and calculator recommendations — in 14 languages.
• Optional light theme and a new settings page.
Still no network, no trackers, no data collection.
The developer, Eric Naville, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Eric Naville
- Size
- 33.1 MB
- Category
- Education
- Compatibility
Requires iOS 13.0 or later.
- iPhone
Requires iOS 13.0 or later. - iPad
Requires iPadOS 13.0 or later. - iPod touch
Requires iOS 13.0 or later. - Mac
Requires macOS 10.15 or later. - Apple Watch
Requires watchOS 10.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Eric Naville