Comparison

InkCalc vs Sigma Notepad Calculator

Price, ratings, monetisation and update history for both apps, side by side β€” with what reviewers say about each.

Head to head
About

InkCalc

Features
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Write "29 dollars an hour, 22 hours a week, for 4 weeks." Tap AI. Get 2,552. InkCalc is a calculator you write in sentences. No re-punching numbers into a keypad, no wondering what that figure was for. Units, live currency, dates and percentages all work inline, right in your notes. Write expressions line by line and results appear on the right, accumulating over time alongside written notes β€” a calculator built to be kept open as a long-running notebook, not a scratchpad. For iPhone, iPad and Mac. Universal Purchase means one subscription covers all three. Starts with a 1-month free trial (auto-renews after that β€” see SUBSCRIPTION below for details). β€” AI-NATIVE ACTIONS (subscription required) β€” AI β€” Natural language to expression Write "29 dollars an hour, 22 hours a week, for 4 weeks", tap the AI button in the toolbar, and AI converts it to `29 * 22 * 4`. Fix β€” AI fixes errors With one tap, AI replaces a parser-failed line with a corrected expression. Summary β€” One-to-three-line note summary AI reads your whole note and summarizes the intent and conclusion in plain natural language. Intent β€” Intent inference from comments Write a question comment like `# Monthly communications total?`, and AI analyzes the relevant lines and inserts a summing formula directly below the question. Backends: Apple Intelligence (default, on-device or via Apple Private Cloud Compute with end-to-end encryption β€” neither the developer nor any third party can read the data), or bring-your-own-key options. With a bring-your-own-key backend, the user supplies their own credentials and prompts are sent to the chosen provider. β€” CALCULATOR FEATURES β€” β€’ Unit math: `5 km in miles`, `1 kg as lb`, `100 USD in JPY` β€’ Real-time currency conversion (USD, EUR, JPY, GBP, and more) β€” subscription required β€’ Percent: `20% of 100`, `1000 + 10%` β€’ Hex / binary / octal literals + bitwise ops: `0xff & 0x0f`, `255 in hex` β€’ Line references: `ans`, `line2`, `sum above`, `avg above`, `total` β€’ Dates: `2025-04-25 + 7 days`, `today + 30 days`, date diff in days β€’ Functions: sqrt, sin/cos/tan, ln/log, round/floor/ceil, sum/min/max/avg, and more β€’ Constants: pi, e, tau β€’ Variables: assign with `x = 5` and reuse on later lines β€” AS A CALCULATION NOTE β€” β€’ Multiple notes + folder selection. Each note is a local `.inkcalc` file. β€’ iCloud Drive sync keeps your notes up to date across iPhone, iPad, and Mac. β€’ Open `.inkcalc` files directly from the Files app. β€’ Export to Markdown / CSV. β€” UI β€” β€’ Designed for iPhone and iPad (two-pane list + editor layout on iPad) β€’ Quick bar above the keyboard: comment toggle and one-tap calculator symbols β€’ Dark, minimal UI with a light/dark appearance setting β€’ Adjustable font size and decimal precision β€” PRIVACY β€” The developer collects nothing β€” no server, no telemetry, no analytics. With Apple Intelligence as the backend, requests stay on-device or are processed through Apple Private Cloud Compute with end-to-end encryption β€” neither the developer nor any third party can read the data. See the in-app privacy policy for details. β€” SUBSCRIPTION β€” β€’ Title: InkCalc Monthly (auto-renewable subscription) β€’ Length: 1 month, auto-renewing β€’ Price: $1.99 / month (Apple displays your local price in-app) β€’ Free trial: 1 month for new subscribers β€’ Payment is charged to your Apple ID after the trial. The subscription auto-renews unless canceled at least 24 hours before the end of the current period. β€’ Manage or cancel in Settings β†’ [your name] β†’ Subscriptions, or right from the app's own settings screen. β€’ Privacy Policy: https://inkcalc.app/privacy β€’ Terms of Use (Apple Standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ β€” REQUIREMENTS β€” iPhone and iPad: iOS 17.0 or later Mac: macOS 13.0 or later (Apple Silicon and Intel) Universal Purchase β€” one subscription covers all three devices.

About

Sigma Notepad Calculator

Features
Read full description

$610 left this month, before rent went out, and you never typed a sum. Sigma is a notepad that does the math while you write: every line shows its answer, and the total stays in view above the keyboard. Know what’s left before you spend it. Write "pay = $2400", then your bills, "rent: $1200" and "food: $380", and "left = pay - total" shows $820. Rent goes up? Change one number and everything below follows. Split the bill at the table. Dinner for four, tip included, comes to $51.75 each before anyone reaches for a card. Then send the whole note to the group chat as one image, every line and the total included. Know what the trip costs before you book. Flights in dollars, the hotel in euros, the train in Swiss francs: one total, all in, in your own currency. Rates stay live and keep working offline. Never add up the same list twice. Tick what’s paid and the total shows what’s still to pay. Give each part of a list a heading and each part gets its own total. And all the everyday math around it. How many days until an invoice is due. Whether a 220 cm sofa fits an 8 ft wall. What you really saved at the sale. What a week of freelance work comes to. Percentages, units, dates and currencies, written the way you’d say them, with square roots, hex and trigonometry when you need them. Every line answers as you type. No formulas, no grid, and one rule to learn: a colon counts, an equals sign doesn’t. Free: three notes and the full calculator. No ads, no time limit. Sigma Pro keeps every month: unlimited notes, iCloud sync, export to PDF, Markdown and plain text, and five more themes. Sigma Pro is a single payment or monthly. Your notes stay on your iPhone, and iCloud sync uses your own private iCloud database, never our servers. Works in English and French. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://getsigma.app/privacy

Screenshots

InkCalc4 screens
Sigma Notepad Calculator4 screens

Verdict

The call

The clearest difference is device support: InkCalc at 3 against Sigma Notepad Calculator's 1. On price, update cadence, ads and in-app purchases there is nothing between them.

Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. InkCalc sells 1 in-app purchase, starting at $1.99 per month and Sigma Notepad Calculator sells 3 in-app purchases, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

InkCalc ships an update fortnightly, Sigma Notepad Calculator every 2 weeks. The most recent releases landed on October 28, 2026 and October 31, 2026 respectively.

Scorecard1 real difference Β· 5 level
InkCalc versus Sigma Notepad Calculator: the parameters behind the verdict, then further details
ParameterInkCalcSigma Notepad Calculator
PriceFreeFree
Update frequencyFortnightly β€” betterEvery 2 weeks
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, Mac β€” betteriPhone
Requires iOS17.017.0
Further details β€” not scored
Size2 MB18 MB
Age rating4+4+
DeveloperKENTARO SOGASoules Studio Ltd

In-app purchases

1 purchases

InkCalc

Subscriptions1
  • InkCalc Monthly1 Month trial$1.991 Month
3 purchases

Sigma Notepad Calculator

Subscriptions2
  • Monthly$1.991 Month
  • Annual7 Days trial$14.991 Year
One-time1
  • Lifetime$29.99

Questions

Is InkCalc free?
InkCalc is free to download, with in-app purchases available.
Is Sigma Notepad Calculator free?
Sigma Notepad Calculator is free to download, with in-app purchases available.
Do InkCalc or Sigma Notepad Calculator have ads?
Neither InkCalc nor Sigma Notepad Calculator shows ads.
Which is updated more often, InkCalc or Sigma Notepad Calculator?
InkCalc ships an update fortnightly, and Sigma Notepad Calculator every 2 weeks. Most recently, InkCalc was updated on October 28, 2026 and Sigma Notepad Calculator on October 31, 2026.

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