# CalcStak — A RPN Calculator

> A RPN Calculator (iPhone/iPad app by JOEL ANDREW ROSINBUM.)

- Source: https://appshunter.io/ios/app/calcstak/id6766592809 (this page in markdown: same URL + `.md`)
- Developer: [JOEL ANDREW ROSINBUM](https://appshunter.io/developer/1896305700)
- Category: Utilities, Finance
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-06-02
- Data updated: 2026-07-17
- User reviews in markdown: https://appshunter.io/ios/app/calcstak/id6766592809/reviews.md

## What is CalcStak?

A reverse-Polish-notation calculator built for the keyboard-first crowd: enter, op, done. No equals key, no parentheses, no nested expressions to babysit.

WHY RPN
If you've used an HP-12C, a Forth REPL, or any stack-based calculator, you already know: RPN is faster once your fingers know the moves. This app puts that experience on your phone without the skeuomorphic clutter.

FEATURES
• Stack display - see four levels at a glance, scroll deeper.
• Full keyboard - numeric pad, operators, and stack manipulation (swap, drop, roll, LASTX).
• Configurable angle mode (degrees / radians), stack mode (unlimited or HP-classic four-deep), and ENTER behavior.
• Storage registers (STO/RCL 0–9) for holding values across calculations.
• History - every operation, scrollable; tap a row to push that past result onto the stack. Capped at the most recent 150 entries.
• Optional Scientific pack (one-time in-app purchase): trig + inverses, log/ln, 10^x/e^x, powers, roots, π and e.
• Dark mode and a calm, monospace-forward design.
• Offline-only. No tracking, no analytics, no network calls. Your math stays on your phone.

NOT INCLUDED (BY DESIGN)
• No "infix mode." This is RPN. If that's not what you wanted, this isn't your app.
• No cloud sync. Yet.
• No ads, ever.

PRIVACY
CalcStak collects nothing. The app does not make network requests. Settings and history are stored on-device.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Scientific Functions | $2.99 | one-time |



## Version history (last 1 release)

### 1.0 — 2026-06-02

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-17.*