Comparison

Slide Rule vs RPN

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

Head to head
About

Slide Rule

Simulates a mechanical analog computer for scientific and engineering calculations. Perform multiplication, division, roots, and trigonometric functions with a digital slide rule.

Highlights
  • Multiplication and division
  • Square and cube roots
  • Trigonometry functions
  • Logarithm calculations
  • Digital slide rule simulation
  • Mechanical analog computer
Features
Read full description

This app is a slide rule simulator. The slide rule (a.k.a. slipstick) is an mechanical analog computer which was formerly used for various scientific calculations, engineering design and surveying. It consists of three linear strips and a sliding cursor and is used for multiplication, division, square, cube, square root, cubic root, trigonometry, logarithm and so on. Please note that trigonometry and logarithm are not supported and the width of the scale is 1,000 pixels in this version.

About

RPN

This app is a detailed simulation of a 1973 scientific calculator, offering a photorealistic interface and all original functions. It includes powerful enhancements for modern use, such as complex number support and advanced date calculations.

Highlights
  • Photorealistic calculator simulation
  • Full HP-45 function implementation
  • Complex number support
  • Advanced date and time functions
  • Printer simulation for calculation records
  • Stopwatch functionality
  • Cut/copy/paste display values
Features
Read full description

RPN-45 SD is a complete simulation of the scientific hand-held calculator HP-45 from 1973. Powerful enhancements turn the calculator into an amazingly useful tool for the 21st century. Features: • Photo-realistic look based on an existing device • Original LED display or high-contrast LCD display • Printer to keep a record of calculations • Animated keys with adjustable click sound and visual feedback • Simulation of the HP-45's computation times (may be disabled) • All functions and operations of the HP-45 fully implemented • "Secret" stopwatch implemented, extensible from 12 to 100 hours capacity • Stopwatch may be preset to current time • Swipe left across display to correct wrong number entries • Cut/copy/paste of display value • Tap display to show stack and all memory registers • Complex numbers may be used in almost all operations • Non-volatile stack and registers • 18 storage locations (9 in complex number mode) • Exponentiation and factorial accept any values (incl. complex) • Optional hyperbolic functions • Logarithm to any base (incl. complex) • Solve linear equations in two or three unknowns • Solve quadratic and cubic equations • Normal distribution, Pearson correlation coefficient of paired variables • Linear regression with estimates • Weighted mean • Permutation, Combination (binomial coefficient) • Integer and fractional part of a number • Display rounding • Random numbers in any range, integer or real • Day of the week of any date between Jan 1, 0001 and Dec 31, 9999 • Easter date for any year between 1583 and 4099 • Support for Julian dates • Date and day of the week a number of days away (past or future) • Number of days between any two dates • Last Stack operation • Show display value in hexadecimal • Percentage of sum • Register arithmetic includes summation registers and LAST x • Indicators for active prefix keys • Angular mode indicator • Localized decimal point • Thousand's separator • Clear all registers • Backup registers in a protected area Double-tap the display for some basic hints. Also available for iPad (RPN-45 HD). For more information, a manual and sample calculations visit the RPN-45 website: cuveesoft.ch/rpn45/en What users said: "Have been using HP RPN calculators since HP-35 first came out. The CuVée versions for Apple products are the best emulations by far. I have, and regularly use, them all." "This app is a great emulator of the classic HP-45 Scientific Calculator, in look, feel and function. It keeps getting better and better with each update." "This is the most like the real thing that I've used. I've bought others but keep coming back to this App. It's photorealistic, the LEDs appear the way the real ones do, and the buttons almost give the same satisfying feedback of the real thing."

Screenshots

Slide Rule3 screens
RPN4 screens

Verdict

The call

The clearest difference is rating: RPN at 4.3 against Slide Rule's 1.0. RPN also leads on update cadence (every 4 months vs every 29 months) and ratings volume (15 vs 1). Slide Rule's advantage is price ($0.99 vs $1.99). On review sentiment, ads, in-app purchases and monetization model 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

CostPrice · In-app purchases · Ads · Monetization

Slide Rule costs $0.99 and RPN $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

RPN holds the better App Store score, 4.3 against 1.0. That said, the two scores are not equally well evidenced: RPN has 15 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 75% of Slide Rule's written reviews are positive against 82% of RPN's.

UpkeepUpdate frequency

Slide Rule ships an update every 29 months, RPN every 4 months. The most recent releases landed on October 27, 2026 and October 20, 2026 respectively.

Scorecard5 real differences · 5 level
Slide Rule versus RPN: the parameters behind the verdict, then further details
ParameterSlide RuleRPN
Price$0.99 — better$1.99
Rating1.0 (1 ratings)4.3 (15 ratings) — better
Positive reviews75.0% of reviews81.8% of reviews — better
Number of ratings115 — better
Update frequencyEvery 29 monthsEvery 4 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPadiPhone, iPod
Requires iOS17.012.0 — better
Further details — not scored
Size3 MB14 MB
Age rating4+4+
DeveloperMasayuki AkamatsuCuVee Software

Customer experience

Slide Rule

All ratings1 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews24 reviews
Positive75.0%
Neutral4.2%
Negative20.8%

RPN

All ratings15 ratings
Positive80.0%
Neutral0.0%
Negative20.0%
Written reviews11 reviews
Positive81.8%
Neutral0.0%
Negative18.2%

In-app purchases

None

Slide Rule

No in-app purchases

None

RPN

No in-app purchases

Questions

Is Slide Rule free?
Slide Rule costs $0.99, with no in-app purchases.
Is RPN free?
RPN costs $1.99, with no in-app purchases.
Which has better reviews, Slide Rule or RPN?
RPN is rated higher. Slide Rule averages 1.0 out of 5 from 1 ratings, while RPN averages 4.3 from 15 ratings.
Do Slide Rule or RPN have ads?
Neither Slide Rule nor RPN shows ads.
Which is updated more often, Slide Rule or RPN?
Slide Rule ships an update every 29 months, and RPN every 4 months. Most recently, Slide Rule was updated on October 27, 2026 and RPN on October 20, 2026.

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