Ruler vs CPD Mastery
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Ruler
This app displays various measurement scales for length, including meters and inches. It allows users to set magnification ratios and reduced scales for different applications. Users can calibrate the ruler and adjust PPI settings for accurate measurements.
- Display various measurement scales
- Set magnification ratios
- Set reduced scales
- Measure in meters and inches
- Free mode for custom scales
- Calibration for accuracy
- PPI setting
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Scale Ruler is the simple application to display the scale of various measurement units. ※ Warning: - The accuracy of the scales cannot be guaranteed. - Calibration and PPI values will be reset when the model changes. - Set the PPI value only when the model is undecided. - When you change the PPI value, perform calibration after the change. ■How to use: ■Select mode In UNLOCKED state, after choosing measurement unit, magnification ratio and reduced scale, the scale is displayed. ■Free mode When dragging the screen at UNLOCK, you can set the scale in the range 1: 1 to 1: 100. When you press and hold the scale value, the keyboard is displayed and you can enter the scale. You can lock the scale on the ruler with a switch. Sorry for the advertisement during unlocking. After In-App Purchase, your ads will no longer be displayed. Specification of Scale Ruler - measure length meter,inches - magnification ratio 50% , 70.7% , 100% , 141% , 200% - reduced scale for meter 1:100 , 1:150 , 1:200 , 1:250 , 1:300 , 1:400 , 1:500 , 1:600 for inch 1:1 , 1:1.5 , 1:2 , 1:2.5 , 1:3 , 1:4 , 1:5 , 1:6 for inch(Architectural) 1:1 , 1:2 , 1:4 , 1:8 , 1:12 , 1:16 , 1:24 , 1:32 , 1:48 , 1:64 1:96 , 1:128 , 1:192 , 1:384 for inch(Engineering) 1:120 , 1:240 , 1:360 , 1:480 , 1:600 , 1:720 1:800 , 1:960 , 1:1080 ■ Settings - Calibration - PPI (pixels per inch) setting - In-app purchase (ads not displayed) - In-app purchase restoration ■ Calibration Adjust the length of the ruler. Use the correct ruler for adjustment. "Calibration" button: Records the adjusted state and reflects the calibration result on the ruler. "Reset" button: Returns the adjustment status to the specified value. It will not be recorded. "Initialize" button: Returns the adjustment status to the specified value and reflects it on the ruler. * Caution: The calibration value will be reset when the model changes. ■ PPI (pixels per inch) setting If the model is undecided, check the PPI value of the model before setting the PPI value. * Please set only when the model is undecided. "OK" button: Record the entered PPI value and reflect it on the ruler display. "Initialize" button: Returns the PPI value to the specified value and reflects it on the ruler. * Caution: The PPI value will be reset when the model changes.
CPD Mastery
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Your CPD Tracker. Smarter. Simpler. More rewarding. Built for lifelong learners and professionals who need more than a spreadsheet — this app helps you document, track, and earn CPD credit hours with ease. Plus, it’s audit-ready when you need it most. Whether you're logging daily reflections, sharing research, or planning your next learning goals — everything is stored, synced, and secure in one sleek mobile App. Key Features: - Log CPD activities in minutes - Record learnings, reflect on research papers, and document your self-directed studies. - Be audit-ready anytime - Download detailed CPD reports, and store verified certificates — all organized and ready for review. - Share original research. When others download your work, you earn commissions as passive income. - Track your progress live Visualize your yearly CPD goals, sort activities by type, and monitor your hours as you go. Terms of Use (EULA): https://cpdmastery.com/terms-and-conditions/
Screenshots
Verdict
The clearest difference is ads: CPD Mastery at none against Ruler's shown. CPD Mastery also leads on update cadence (monthly vs every 5 months). On price, in-app purchases, device support and iOS requirement 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
Both are free to download. Ruler sells 1 one-off in-app purchase and CPD Mastery sells 1 in-app purchase, starting at $9.99 per month. Whichever you choose, the download price is not the number that matters.
Ruler ships an update every 5 months, CPD Mastery monthly. The most recent releases landed on October 13, 2026 and October 5, 2026 respectively.
| Parameter | Ruler | CPD Mastery |
|---|---|---|
| Price | Free | Free |
| Rating | 3.7 (3 ratings) — better | — |
| Positive reviews | 63.0% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 5 months | Monthly — better |
| Ads | Yes | No — better |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 — better | 15.1 |
| Further details — not scored | ||
| Size | 4 MB | 40 MB |
| Age rating | 4+ | 17+ |
| Developer | mitsunori oishi | Craig Bartlett |
In-app purchases
Ruler
- Hide Ads$0.99
CPD Mastery
- CPD Mastery Premium$9.991 Month









