Physical Constants vs Pocket 991
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Physical Constants
Access a comprehensive list of physical constants, organized by category for easy searching. This app supports all AppStore languages and allows users to report corrections via email.
- Physical constants database
- Categorized by topic
- Search functionality
- Multi-language support
- User feedback for corrections
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Application that displays the physical constants. Classified by category, easy to search. Supports all languages in the AppStore. If you find something to be corrected, please send an E-mail (English or Japanese).
Pocket 991
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A scientific and graphing calculator that shows you which keys to press. Pocket 991 brings together familiar EX- and CW-style scientific-calculator workflows, an independent CG50-style graphing calculator, and a large library of interactive tutorials for A-level Maths and Further Maths students. FOLLOW THE HIGHLIGHTED KEYS Choose a tutorial or ask how to do something. Clear requests start guidance; broader questions offer relevant operations. Follow a worked example on the calculator itself, then take over whenever you are ready. SCIENTIFIC CALCULATOR WORKFLOWS • Polynomial and simultaneous equations • Normal, binomial and Poisson probabilities • Statistics and regression • Matrix and vector calculations • Complex numbers • Numerical integration, differentiation and tables • Fractions, powers and calculator settings CG50-STYLE GRAPHING Explore calculations, graphs, tables, equations, statistics and distributions, matrices, recursion, conics, selected 3D workflows and more. The CG50 learning interface includes 234 worked tutorials with model-specific keys, menus and graphing steps. BUILT FOR YOUR PHONE AND TABLET Full-screen calculator layouts, tactile key feedback, an integrated question keyboard and optional dictation. Calculations and built-in tutorials work offline. Natural-language interpretation uses Apple Intelligence on compatible devices; availability depends on device, operating system, language and settings. Pocket 991 is an independent educational calculator and tutorial tool. It is not official calculator firmware and is not made by or affiliated with a calculator manufacturer. Some specialist modes, interfaces and numerical precision differ from physical calculators. Numerical calculus is supported; general symbolic algebra is not. This is a practice tool, not an examination device.
Screenshots
Verdict
The clearest difference is price: Physical Constants at Free against Pocket 991's $0.99. Physical Constants also leads on iOS requirement (12.0 vs 17.0). Pocket 991's advantage is ads (none vs shown) and update cadence (fortnightly vs every 9 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
Physical Constants is free to download; Pocket 991 costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Physical Constants ships an update every 9 months, Pocket 991 fortnightly. The most recent releases landed on November 1, 2026 and October 31, 2026 respectively.
| Parameter | Physical Constants | Pocket 991 |
|---|---|---|
| Price | Free — better | $0.99 |
| Rating | 3.3 (3 ratings) — better | — |
| Positive reviews | 33.3% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 9 months | Fortnightly — better |
| Ads | Yes | No — better |
| In-app purchases | No | No |
| Monetization | Ad-supported | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 12.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 25 MB | 12 MB |
| Age rating | 4+ | 4+ |
| Developer | Takuya Ishikawa | Charlie Candlish |
In-app purchases
Physical Constants
No in-app purchases
Pocket 991
No in-app purchases
Questions
Is Physical Constants free?
Is Pocket 991 free?
Do Physical Constants or Pocket 991 have ads?
Which is updated more often, Physical Constants or Pocket 991?
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