UnitConverter byNSDev vs TechRef
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
UnitConverter byNSDev
This tool converts between 26 different types of units, displaying conversion rates and allowing you to specify decimal places. It supports a vast array of units across categories like length, mass, volume, and more.
- Converts 26 types of units
- Displays conversion rates
- Customizable decimal places
- Supports numerous units in various categories
- User-submitted unit requests
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Tool to convert each of 26 types of units. When you select a unit of value that you enter, you create a table to calculate all the other units. It also displays the conversion rate. You can also specify the number of decimal places. 23 units in Length 18 units in Area 31 units in Volume 15 units in Mass 5 units in Angle 4 units in Temperature 7 units in Time 3 units in Frequency 5 units in Force 17 units in Pressure 6 units in Energy 6 units in Power rate 13 units in Speed 14 units in Acceleration 2 units in Dynamic viscosity 4 units in Kinematic viscosity 3 units in Magnetic flux density 2 units in Magnetic flux 7 units in Luminance 4 units in Illuminance 3 units in Radiation - source activity 2 units in Radiation - absorbed dose 2 units in Radiation - equivalent dose 2 units in Radiation - exposure 7 units in Infomation 7 units in Resolution Because we want to support units around the world, We will wait for the name and unit conversion information. Please enter your review.
TechRef
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The drawing says 50.000 +0.200 / -0.000. The machine needs 50.100. TechRef does that math, converts it into every unit, and records what you measure. Built for the everyday questions on the shop floor. WHY THE CENTER VALUE MATTERS The center of an asymmetric tolerance is not the nominal size. TechRef calculates the true center and the full band, so you get it right in one setup. Input: 50.000 +0.200 / -0.000 Center: 50.100 Range: 50.000 – 50.200 mm 50.1000 (50.0000 – 50.2000) in 1.9724 ( 1.9686 – 1.9763) TOLERANCES FROM THE STANDARD (TechRef Pro) Pick an ISO 2768 class (f, m, c, v) or an ISO 286 fit (hole H7, shafts g6 to p6), and TechRef looks up the deviations for your size. Pick a shaft to see how it fits an H7 hole: clearance, transition or interference. Use ISO, JIS, EN, DIN or BS names; only standards officially identical to ISO are listed. TABLES AND CALCULATORS • Tolerance tables (TechRef Pro): ISO 2768 and ISO 286 (H7, g6 to p6, fits with H7), up to 500 mm • Tap drill charts (TechRef Pro): Metric, Unified and Whitworth, with minor diameter limits. Sizes that could not be verified are left out • Drill size charts: number, letter and fractional drills in inches and mm • Cutting speed and feed: spindle speed, cutting speed and feed rate, in mm and m/min or inch and SFM. Formulas only RECORD WHAT YOU MEASURE Add measured values to any point in a sheet. Each entry updates the count, mean, max, min, range, standard deviation, deviation from target, out-of-tolerance count, Cp and Cpk. Drawing: 25.000 ±0.100 Measured: 25.02 / 25.05 / 24.98 / 25.12 / 25.03 Mean: 25.040 (+0.040 from target) Out of tolerance: 1 / 5 The target is the tolerance center, so you see which way to adjust. Drawing in mm, measuring in inches? Record in your own unit. Free, and not counted toward the save limit. INSPECTION SHEETS AND CSV Create a sheet per part with points, each with its own dimension and tolerance. Export CSV per point or per measured value. 13 CATEGORIES, 100+ UNITS Length, pressure, torque, force, temperature and more. Show only the units you use, from mm and inch to bar, psi, kgf/cm², N·m and lbf·ft. Factors come from exact definitions, never rounded approximations. SAFE-SIDE ROUNDING Bands are rounded inward, so a part inside the band on screen is inside it for real. 10 LANGUAGES English, Japanese, German, French, Italian, Spanish, Portuguese, Korean, Simplified Chinese and Traditional Chinese. Follows your device, or choose in Settings. FREE, AND TechRef Pro Conversions, manual tolerances, drill charts, the cutting calculator, Sheets, measured values and CSV export are free. Saving dimensions has a limited number of free saves, then once per hour. TechRef Pro, a one-time purchase, removes the limit and unlocks tap drill charts, tolerance tables and tolerances from the standard. No subscription. EVERYTHING STAYS ON YOUR DEVICE No server, fully offline. No ads, no tracking, no analytics, no account. ALSO History with search, labels and memos · 1 to 6 decimal places · How to Use · Dynamic Type · Light and dark · iPhone and iPad
Screenshots
Verdict
The clearest difference is in-app purchases: UnitConverter byNSDev at none against TechRef's 1. UnitConverter byNSDev also leads on iOS requirement (15.6 vs 17.6). TechRef's advantage is update cadence (every 3 days vs every 5 months). On price, 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
Both are free to download. TechRef sells 1 one-off in-app purchase. UnitConverter byNSDev asks for nothing beyond the download.
UnitConverter byNSDev ships an update every 5 months, TechRef every 3 days. The most recent releases landed on October 4, 2026 and October 11, 2026 respectively.
| Parameter | UnitConverter byNSDev | TechRef |
|---|---|---|
| Price | Free | Free |
| Positive reviews | 20.0% of reviews | — |
| Update frequency | Every 5 months | Every 3 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.6 — better | 17.6 |
| Further details — not scored | ||
| Size | 4 MB | 4 MB |
| Age rating | 4+ | 4+ |
| Developer | NIHON SYSTEM DEVELOPER CORPORATION | MASARU KATO |
In-app purchases
UnitConverter byNSDev
No in-app purchases
TechRef
- TechRef Pro$6.99
Questions
Is UnitConverter byNSDev free?
Is TechRef free?
Do UnitConverter byNSDev or TechRef have ads?
Which is updated more often, UnitConverter byNSDev or TechRef?
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