Plus42 vs X CalcKits
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Plus42
This advanced scientific calculator simulates the HP-42S RPN calculator with enhanced features. It offers algebraic expressions, unit conversions, directories for storage, a larger resizable display, time value of money functions, and 2D plotting with integral and root finding.
- HP-42S RPN calculator simulation
- Algebraic expressions
- Attached units and conversions
- Program and variable directories
- Resizable 8-row, 22-column display
- Time value of money and amortization
- 2D function plotting with zoom and pan
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Plus42 is an advanced scientific programmable calculator, based on Free42. Free42, in turn, is a complete re-implementation of the HP-42S scientific programmable RPN calculator, which was made from 1988 until 1995 by Hewlett-Packard. Free42 is a complete rewrite and contains no HP code whatsoever. Plus42 builds on Free42 and adds: Algebraic expressions modeled after those used on the HP-27S and HP-17B/19B; attached units and unit conversions modeled after those used on the HP-48/49/50 series; directories for more organized storage of programs and variables; a larger display, with 8 rows and 22 columns (131x64 pixels) by default, which the user may resize at will; time value of money and amortization schedules; and two-dimensional plotting of functions, with ability to zoom and pan, and find integrals and roots from points in the plot.
X CalcKits
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This newly developed multi-functional calculator breaks the limitations of traditional calculators that only support basic four arithmetic operations. It integrates a full range of practical functions including scientific calculation, unit conversion, numeral system conversion, mortgage/personal income tax estimation, and real-time exchange rate calculation.
Screenshots
Verdict
The clearest difference is price: X CalcKits at Free against Plus42's $9.99. X CalcKits also leads on iOS requirement (13.0 vs 15.0). Plus42's advantage is ads (none vs shown) and update cadence (every 8 days vs every 4 months). On in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
X CalcKits is free to download; Plus42 costs $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Plus42 ships an update every 8 days, X CalcKits every 4 months. The most recent releases landed on November 12, 2026 and November 5, 2026 respectively.
| Parameter | Plus42 | X CalcKits |
|---|---|---|
| Price | $9.99 | Free — better |
| Rating | 4.9 (80 ratings) — better | — |
| Positive reviews | 92.5% of reviews | — |
| Number of ratings | 80 — better | — |
| Update frequency | Every 8 days — better | Every 4 months |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Paid | — |
| Best chart rank | #182 — better | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 13.0 — better |
| Further details — not scored | ||
| Size | 12 MB | 31 MB |
| Age rating | 4+ | 4+ |
| Developer | Thomas Okken | Singxi Limited |
In-app purchases
Plus42
No in-app purchases
X CalcKits
No in-app purchases
