Slate: Calculator

Eight calculators. One slate.

Sums, percent, dates, tips, units, loans, GST and exchange, on one keypad that clicks like it means it.

  • No ads
  • No accounts
  • No subscriptions
Get it on Google Play

Try the keys

50 + 10% =

55

Slate's basic keys, working. Percent works the desk way: 50 + 10% is 55. Type on your keyboard too; arrow keys move around the pad.

Skin

Chalk is free. The other six come with Slate Pro.

At a glance

What Slate is for

The everyday jobs that usually end up in a browser tab, or a guess.

Add GST, or take it back out. Inc and ex prices, at any rate.
Count the days to the big day. Days between dates, or a date plus days.
Cast your sums to the TV. Because why not.

Backgrounds are illustrations; the phone screens are the real app.

The tools

Eight tools, one keypad

Calculator, Percent and Date are free, and complete. The other five come with Slate Pro.

  • Calculator Free

    Basic for everyday sums, and one tap opens the scientific keys: trig and inverses, logs, roots, powers, factorials, π and e. The tape above the display remembers recent results.

  • Percent Free

    Discounts, markups, and "what percent of what" sums.

  • Date Free

    Days between dates, add or subtract days, work out an age.

  • Tip Pro

    Split the bill fairly, down to the cent.

  • Units Pro

    Length, weight, volume, temperature and more.

  • Loan Pro

    Repayments and total interest at a glance.

  • GST Pro

    Add it to a quote or pull it out of a total, at any rate.

  • Exchange Pro

    Convert currencies on European Central Bank reference rates, and keep the last table on the phone.

Every tool runs on the same skinned keypad, and the system keyboard never appears.

History

Every sum remembered

Slate keeps the calculations you finish, newest first. Tap one and it loads straight back into the tool that worked it out, ready to change. Clearing the list is two taps.

Skins and sounds

Seven skins, each with its own key sounds

Slate ships in chalk. Slate Pro re-dresses every tool, and every skin pairs with its own set of key sounds.

  • Chalk

    Chalk taps

    Free

  • Ledger

    Typewriter, with a carriage bell on equals

    Pro

  • Terminal

    Beeps, in green phosphor

    Pro

  • Porcelain

    Droplets, on clean white

    Pro

  • Ember

    Woodblock, by warm coals

    Pro

  • Drift

    Hush, in dusk violet

    Pro

  • Blueprint

    Abacus, in cyanotype lines

    Pro
  • Try them on the slate
The calculator in Chalk: a worked sum on the slate board, the result tape above the display, the scientific keys open and the cast button in the top bar
The chalk board, and the tape that remembers
The calculator dressed in Blueprint: cyanotype blue board with pale line-work keys, a multiplication in progress
Blueprint's cyanotype lines
The Loan tool in Ledger: paper-and-ink board with amount, rate and years filled in, repayment and total interest worked out
Loan, in Ledger's paper and ink
The Date tool in Porcelain: a clean white board showing the days between two dates in July and December 2026
Date, in Porcelain's clean white
The Units tool in Terminal: green phosphor glow on a dark board, kilometres converted to miles
Units, in Terminal's phosphor glow
Settings in Ember: warm coals palette, the seven skins listed with their key sounds
Every skin pairs with its own key sounds

Six screens from the Google Play listing, captured from the app on a phone.

Cast it

Your working, on the big screen

Cast to a TV and Slate mirrors whichever tool is up: same numbers, same skin, while your phone stays the keypad. Walk away and an idle cast tidies itself up after a few minutes.

Cast to your TV from Android or iPhone

Casting needs the internet: your TV loads Slate's display page from our studio site, zone7studios.com, and casting uses Google's Cast framework, which is covered by Google's privacy policy.

Free, and Pro

Complete without paying

Slate

  • The full basic and scientific calculator
  • Percent and Date
  • The tape, and the History
  • The Chalk skin and its key sounds
  • Casting to your TV

Slate Pro one purchase

  • Tip, Units, Loan, GST and Exchange
  • The other six skins, and every sound set
  • The skins and sounds we add later, too

A single one-time purchase inside the app. Pay once, own it forever, and no subscription, ever.

Not sure yet? Pick a Pro calculator from the menu and it works for real for ten seconds, once a day for each one.

Quiet by design

What Slate will never do

Your sums are yours. Slate keeps your settings and calculation history on your device.

Slate uses the network for Exchange's published reference rates, for the store's billing for the one-time purchase, and for casting to your TV if you use it.

We receive anonymous usage stats. Read the privacy page

Not settings you have to find and switch off. Not in the app at all.

  • Ask for an account or a sign-in
  • Carry an ad, or an ad SDK
  • Charge you weekly, monthly or yearly
  • Upload your sums anywhere
  • Pop up the system keyboard
  • Beg you for a rating
  • Interrupt you with an upsell

Get Slate

On Google Play. Calculator, Percent and Date are yours from the first tap, and Slate Pro is one purchase inside the app.

Get it on Google Play

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