ISO Fits vs Thread Calculator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ISO Fits
Calculate ISO fits and tolerances for shafts and bores. Supports metric and inch units, displays detailed fit definitions, and includes visual charts and educational videos.
- ISO fits calculation
- Tolerance class display
- Metric/inch unit switching
- Tolerance charts
- Updated YouTube videos
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It includes the following features: - Fits calculation: Upon entering the nominal diameter (of either bore or shaft), users select their tolerance classes for bore and shaft. The app then provides the complete ISO fits definition with all relevant values. - Tolerances: Shows the tolerances for the most commonly used ISO tolerance classes. - switch between metric and inch version. - Charts: Shows the most common ISO tolerances classes in a diagram. - Videos: Features the automatically updated latest TSS youtube videos. The results of this application are based on DIN ISO 286 Nominal dimension: 1-3150mm following tolerances included: Shaft: a9, a10, a11, a12, a13, b8, b9, b10, b11, b12, b13, c8, c9, c10, c11, c12, cd5, cd6, cd7, cd8, cd9, cd10, d5, d6, d7, d8, d9, d10, d11, d12, d13, e5, e6, e7, e8, e9, e10, ef3, ef4, ef5, ef6, ef7, ef8, ef9, ef10, f3, f4, f5, f6, f7, f8, f9, f10, fg3, fg4, fg5, fg6, fg7, fg8, fg9, fg10, g3, g4, g5, g6, g7, g8, g9, g10, h1, h2, h3, h4, h5, h6, h7, h8, h9, h10, h11, h12, h13, h14, h15, h16, h17, h18, js1, js2, js3, js4, js5, js6, js7, js8, js9, js10, js11, js12, js13, js14, js15, js16, js17, js18, j5, j6, j7, j8, k3, k4, k5, k6, k7, k8, k9, k10, k11, k12, k13, m3, m4, m5, m6, m7, m8, m9, n3, n4, n5, n6, n7, n8, n9, p3, p4, p5, p6, p7, p8, p9, p10, r3, r4, r5, r6, r7, r8, r9, r10, s3, s4, s5, s6, s7, s8, s9, s10, t5, t6, t7, t8, u5, u6, u7, u8, u9, v5, v6, v7, v8, x5, x6, x7, x8, x9, x10, y6, y7, y8, y9, y10, z6, z7, z8, z9, z10, z11, za6, za7, za8, za9, za10, za11, zb7, zb8, zb9, zb10, zb11, zc7, zc8, zc9, zc10, zc11 Bore: A9, A10, A11, A12, A13, B8, B9, B10, B11, B12, B13, C8, C9, C10, C11, C12, C13, CD6, CD7, CD8, CD9, CD10, D6, D7, D8, D9, D10, D11, D12, D13, E5, E6, E7, E8, E9, E10, EF3, EF4, EF5, EF6, EF7, EF8, EF9, EF10, F3, F4, F5, F6, F7, F8, F9, F10, FG3, FG4, FG5, FG6, FG7, FG8, FG9, FG10, G3, G4, G5, G6, G7, G8, G9, G10, H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, H16, H17, H18, JS1, JS2, JS3, JS4, JS5, JS6, JS7, JS8, JS9, JS10, JS11, JS12, JS13, JS14, JS15, JS16, JS17, JS18, J6, J7, J8, J9, K3, K4, K5, K6, K7, K8, K9, K10, M3, M4, M5, M6, M7, M8, M9, M10, N3, N4, N5, N6, N7, N8, N9, N10, N11, P3, P4, P5, P6, P7, P8, P9, P10, R3, R4, R5, R6, R7, R8, R9, R10, S3, S4, S5, S6, S7, S8, S9, S10, T5, T6, T7, T8, U5, U6, U7, U8, U9, U10, V5, V6, V7, V8, X5, X6, X7, X8, X9, X10, Y6, Y7, Y8, Y9, Y10, Z6, Z7, Z8, Z9, Z10, Z11, ZA6, ZA7, ZA8, ZA9, ZA10, ZA11, ZB7, ZB8, ZB9, ZB10, ZB11, ZC7, ZC8, ZC9, ZC10, ZC11
Thread Calculator
This app provides a quick and easy way to calculate thread dimensions for various units, including tap hole sizes and bolt specifications. It helps metalworkers find precise measurements for internal and external threads without consulting tables.
- Thread cutting calculator for multiple units
- Cold forming calculator
- Thread repair calculator
- Tap hole and bolt diameter calculation
- Saves time compared to tables
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The app includes: - A calculator for thread cutting for the following units: M, MF, UNC, UNEF, UNF, UNR, UNS, NPT, NPTF, NPSC, NPSF, NPSL, NPSM, BA, BSP, BSF, BSW, BSPP, TR, and TRF - A calculator for cold forming - A calculator for thread repair You want to know which tap hole you should drill for threading or which bolt you should use? With this app, you will find the desired measures in no time: Simply select the desired thread type, nominal size, and pitch and you will get the matching diameter for your project. This saves precious time you would have spent tediously searching for internal and external thread dimensions in tables. As this app is still in its development phase, new features will follow soon, so stay tuned! GSR Gustav Stursberg GmbH is a manufacturer for high-quality thread cutting tools with 130 years of operational experience in the area of threading tool production. The product portfolio includes a wide selection of tools for different areas of application. GSR taps, twist drills, round dies, and tool holders are manufactured to the highest quality standards in our own production facilities. The constant quality control during the production process guarantees a consistent good quality in all national as well as international production facilities. This requires enormous precision, which is reflected by our tools. Precision is in the details. Since 1889.
Screenshots
Verdict
ISO Fits and Thread Calculator both sit at 4.2 stars, but that hides the real split: 95% of ISO Fits's written reviews are positive against 33% of Thread Calculator's. ISO Fits also leads on ads (none vs shown) and update cadence (every 5 months vs every 18 months). Thread Calculator's advantage is in-app purchases (none vs 1). On price, rating, ratings volume 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
Both are free to download. ISO Fits sells 1 one-off in-app purchase. Thread Calculator asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 4.2 for ISO Fits against 4.3 for Thread Calculator. Both are backed by a comparable volume of ratings — 6 and 13 respectively. Written reviews are what separate them: 95% of ISO Fits's written reviews are positive against 33% of Thread Calculator's.
ISO Fits ships an update every 5 months, Thread Calculator every 18 months. The most recent releases landed on September 12, 2026 and September 9, 2026 respectively.
| Parameter | ISO Fits | Thread Calculator |
|---|---|---|
| Price | Free | Free |
| Rating | 4.2 (6 ratings) | 4.3 (13 ratings) — better |
| Positive reviews | 94.6% of reviews — better | 33.3% of reviews |
| Number of ratings | 6 | 13 — better |
| Update frequency | Every 5 months — better | Every 18 months |
| Ads | No — better | Yes |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Ad-supported — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.6 | 15.0 — better |
| Further details — not scored | ||
| Size | 66 MB | 25 MB |
| Age rating | 4+ | 4+ |
| Developer | Trelleborg Sealing Solutions | GSR Gustav Stursberg GmbH |
Customer experience
ISO Fits
Thread Calculator
In-app purchases
ISO Fits
- Full Version with complete ISO286 Standard$1.99
Thread Calculator
No in-app purchases
Questions
Is ISO Fits free?
Is Thread Calculator free?
Which has better reviews, ISO Fits or Thread Calculator?
Do ISO Fits or Thread Calculator have ads?
Which is updated more often, ISO Fits or Thread Calculator?
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