GD & T Guide vs PrepFE
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
GD & T Guide
This app provides a digital version of a pocket guide to Geometric Dimensioning and Tolerancing (GD&T). It explains GD&T symbols, their application on engineering drawings, and common inspection techniques. It also includes tools for converting measurements and calculating position tolerances.
- GD&T symbol descriptions
- Engineering drawing application
- Inspection techniques
- Reporting methods
- Measurement conversion tool
- Fastener formula calculator
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This is an App version of our best-selling printed pocket guide on Geometric Dimensioning and Tolerancing (GD&T). In its 77 pages, it will give a description of GD&T symbols and their use on engineering drawings. Common inspection techniques and reporting methods are also included in the descriptions. There is a conversion app for X, Y rectangular measurements to position tolerance zones. There is a fixed and floating fastener formula App to calculate position tolerances using the standard screw and drilled clearance holes. Available in both inch and mm.
PrepFE
Prepare for the FE Mechanical exam with practice problems and flashcards. Learn by doing with expert-curated content, track your progress, and identify areas for improvement. Study conveniently on your mobile device, anytime, anywhere.
- Practice FE exam questions
- Interactive practice exams
- Hundreds of practice questions
- Detailed step-by-step explanations
- Reinforce learning with flashcards
- Breakdown of strengths and weaknesses
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Don't spend time relearning topics from scratch and using poor resources. Jump right into practice problems and learn by doing! Supplement your learning with flash cards to learn the FE Reference Handbook and be familiar with your discipline's concepts. Take your exam practice on the go and learn with our curated content by engineering experts. Study whenever and wherever it’s convenient with PrepFE™. No need to carry around books and study guides. All you need is your phone and determination. Start your Professional Engineer journey and download the PrepFE - Mechanical app. Install the free version today and jump start your studying! We have provided a limited free version of the app that you can try before deciding to upgrade. This version includes a limited set of practice questions, flash cards, and basic progress metrics. *Practice FE exam questions* *Interactive Practice Exams* *Hundreds of Practice Questions* *Detailed & Step-by-Step Explanations* *Reinforce learning with Flash Cards* *Breakdown of strengths and weaknesses* *Updated for 2020* We have up to date content for the new category specifications: • Mathematics • Probability and Statistics • Ethics and Professional Practice • Engineering Economics • Electricity and Magnetism • Statics • Dynamics, Kinematics, and Vibrations • Mechanics of Materials • Material Properties and Processing • Fluid Mechanics • Thermodynamics • Heat Transfer • Measurements, Instrumentation, and Controls • Mechanical Design and Analysis
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Verdict
The clearest difference is rating: GD & T Guide at 3.0 against PrepFE's 2.0. GD & T Guide also leads on iOS requirement (11.0 vs 13.0). PrepFE's advantage is update cadence (every 2 months vs every 5 months) and ratings volume (57 vs 9). On price, review sentiment, ads and in-app purchases 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. GD & T Guide sells 2 one-off in-app purchases and PrepFE sells 6 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.
GD & T Guide holds the better App Store score, 3.0 against 2.0. That said, the two scores are not equally well evidenced: PrepFE has 57 ratings behind it against 9, so its average is the more settled of the two. Written reviews point the same way: 20% of GD & T Guide's written reviews are positive against 17% of PrepFE's.
GD & T Guide ships an update every 5 months, PrepFE every 2 months. The most recent releases landed on October 14, 2026 and October 8, 2026 respectively.
| Parameter | GD & T Guide | PrepFE |
|---|---|---|
| Price | Free | Free |
| Rating | 3.0 (9 ratings) — better | 2.0 (57 ratings) |
| Positive reviews | 20.0% of reviews — better | 16.7% of reviews |
| Number of ratings | 9 | 57 — better |
| Update frequency | Every 5 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 11.0 — better | 13.0 |
| Further details — not scored | ||
| Size | 55 MB | 288 MB |
| Age rating | 17+ | 4+ |
| Developer | GeoTol Inc. | PrepFE, Inc. |
Customer experience
GD & T Guide
PrepFE
In-app purchases
GD & T Guide
- Full Book$1.99
- Geometric Dimensioning and Tec$3.99
PrepFE
- 1 Month Access Renewal$47.99
- 1 Month Access2 variants$59.99
- 3 Months Access Renewal$61.99
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- 6 Months Access Renewal$75.99
- 3 Months Access2 variants$79.99
- 6 Months Access2 variants$99.99
