Comparison

Right Angle vs Slope Calc

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

Head to head
About

Right Angle

This app provides precise calculations for geometric shapes like triangles, trapezoids, and circles. It offers multiple angle and length formats, a custom keyboard for job site use, and helpful error messages. Designed for professionals in construction, engineering, and trades.

Highlights
  • Calculates triangles, trapezoids, and circles
  • Supports decimal degrees, radians, DMS, percent grade, and pitch
  • Handles decimal, feet/inches/fractions length formats
  • Custom on-screen keyboard with job site symbols
  • VoiceOver support for accessibility
  • Available in English and Spanish
Features
Read full description

Right Angle is a calculator built for carpenters, builders, surveyors, machinists, and engineers — anyone who needs to solve a triangle, a trapezoid, or a circle without reaching for a notepad and the law of sines. Enter any valid combination of sides and angles and Right Angle solves the rest, including perimeter and area. The right triangle calculator is included for free; every other shape unlocks with a one-time Pro purchase or subscription. SHAPES • Right triangle (free) • Oblique triangle • Isosceles, right, and general trapezoids • Full circle — enter radius, diameter, or circumference • Segment of a circle ANGLE FORMATS • Decimal degrees • Radians • Degrees / minutes / seconds (DMS) • Percent grade • Pitch (x-over-12) LENGTH FORMATS • Decimal — the original, unitless entry. Best for metric. • Feet, inches & fractions — type values like 2' 5 1/2". • Inches & fractions — type values like 40 1/2". Pick a fraction precision from 1/2 down to 1/64 inch. Inputs and outputs both use the format you choose, and you can switch any time from Settings. DESIGNED FOR THE JOB SITE • A custom on-screen keyboard puts the symbols you need — feet, inches, fraction slash, degree, prime, double-prime — one tap away. • Helpful errors when an input combination can't be solved, instead of silent failures. • Available in English and Spanish — iOS picks the language to match your device. • Full VoiceOver support across the keyboard, input fields, shape diagrams, and results. Animations respect the Reduce Motion setting. EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy policy: http://rightangleapp.com/privacy.html

About

Slope Calc

Features
Read full description

“Why is the size of Calculator each buttons same? “ “How order is the priority of Calculator button? “ “What type Calculator is designed ,According to this priority? “ From those point,I redesign Calculator. Calculator is for Calculation.Not for inputting number. Consequently, the most important button is NOT number buttons. The most important button is 4 arithmetical operation buttons. I design those 4 arithmetical operation button is bigger than 10 number buttons. I put those 4 buttons around number buttons(relative position). And if you incline your iPhone to the direction of top and bottom right and left , you can input 4 arithmetical operation. ・Future function additional plan Equal sign input by the gesture

Screenshots

Right Angle4 screens
Slope Calc2 screens

Verdict

The call

The clearest difference is price: Right Angle at Free against Slope Calc's $0.99. Right Angle also leads on update cadence (every 11 days vs every 21 months). Slope Calc's advantage is in-app purchases (none vs 9) and iOS requirement (7.0 vs 26.0). On ads 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

CostPrice · In-app purchases · Ads · Monetization

Right Angle is free to download; Slope Calc costs $0.99 up front. Right Angle sells 9 in-app purchases, starting at $2.99 per month. Slope Calc asks for nothing beyond the download.

UpkeepUpdate frequency

Right Angle ships an update every 11 days, Slope Calc every 21 months. Both last shipped on November 10, 2026.

Scorecard4 real differences · 6 level
Right Angle versus Slope Calc: the parameters behind the verdict, then further details
ParameterRight AngleSlope Calc
PriceFree — better$0.99
Rating4.0 (31 ratings) — better—
Positive reviews73.3% of reviews—
Number of ratings31 — better—
Update frequencyEvery 11 days — betterEvery 21 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPadiPhone, iPod
Requires iOS26.07.0 — better
Further details — not scored
Size8 MB1 MB
Age rating4+4+
DeveloperJerry MayersYosuke Kurashima

Bugs and requests

Right Angle

Reported bugs

5 issues
  • App crashes after startup
  • Update caused app to crash
  • Loss of previously purchased unlocked app
  • Keyboard covers input fields
  • App changes mm to unspecified units

Requested features

9 requests
  • Restore fraction support
  • Restore feet and inches support
  • Provide both angles of a right triangle
  • Allow scrolling or hiding the keyboard
  • Bundling with other tools
Show 4 more
  • Add metric units (millimeters)
  • Option to choose metric inputs
  • Dark mode option
  • Advanced analytics dashboard

Slope Calc

Not enough reviews yet to summarise bugs or requests.

In-app purchases

9 purchases

Right Angle

Subscriptions2
  • Renews Monthly14 Days trial$2.991 Month
  • Renews Yearly1 Month trial$14.991 Year
One-time7
  • Small Tip$2.99
  • Medium Tip$4.99
  • Segments Calculator$5.99
Show 4 more
  • Oblique Triangle Calculator$5.99
  • Segment & Oblique Triangle$6.99
  • Large Tip$9.99
  • Huge Tip$29.99
None

Slope Calc

No in-app purchases

Questions

Is Right Angle free?
Right Angle is free to download, with in-app purchases available.
Is Slope Calc free?
Slope Calc costs $0.99, with no in-app purchases.
Do Right Angle or Slope Calc have ads?
Neither Right Angle nor Slope Calc shows ads.
Which is updated more often, Right Angle or Slope Calc?
Right Angle ships an update every 11 days, and Slope Calc every 21 months. Most recently, Right Angle was updated on November 10, 2026 and Slope Calc on November 10, 2026.

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