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Best Unit Conversion Apps for iPhone (2026)
Quick answer
Unit Converter - Convert all is the top-ranked of the 19 tiered unit conversion apps on iPhone, at S tier with 4.6/5 from 67,673 ratings.
Tier list
Top 5
- 1
- 2
- 3
★ 4.7 · 23.6K ratings · Free + IAP - 4
★ 4.8 · 114K ratings · Free + IAP - 5
★ 4.6 · 26.0K ratings · Free + IAP
Key takeaways
- Unit Converter - Convert all ranks #1 of the 19 tiered unit conversion apps, S tier with a score of 95 out of 100.
- The highest-ranked free app with no in-app purchases is Metric Conversion tool (#2).
- Unit Converter - Best Unit App has the most App Store ratings here: 403,031, averaging 4.8/5.
- 11 of the 19 tiered apps reach S or A tier.
What belongs in this list
Convert a value from one unit of measurement to another.
Not here: currency conversion alone; image, audio or video file conversion alone; a basic calculator alone; a general chatbot that can do unit math alone
How we pick
For this list we ask the App Store the same searches a person would, in several countries, and keep every app it returns. A model reads each app's listing and rejects the ones that only mention the use case. Every app that stays is scored out of 100 from four parts, each 0 to 100 and averaged: its App Store rating, how many people rated it, where the App Store itself ranks it for this list's searches, and how recently its current version shipped. An app showing Apple's Editors' Choice badge gets a fifth part of 100, which can only lift its score. Apps whose maker has verified ownership get a small score component, because an active maker is a sign the app is kept up to date. It never decides a tier on its own. Updated daily. Tiers follow fixed score bands: S from 90, A from 80, B from 70, C from 60, D from 50, F below. On a list of 20 or more ranked apps, a tier from S to D takes in new apps only up to a quarter of the top 40: an app pushed out of a full tier falls to the next tier with room, and F takes the rest. Read the full method →
Compare every app
| # | App | Tier | Score | Rating | Ratings | Price | Updated |
|---|---|---|---|---|---|---|---|
| 1 | Unit Converter - Convert allBest overall | S | 94.5 | 4.6 | 67,673 | Free + IAP | |
| 2 | Metric Conversion toolBest free | S | 94.1 | 4.8 | 25,199 | Free download | |
| 3 | S | 93.5 | 4.7 | 23,565 | Free + IAP | ||
| 4 | S | 93.4 | 4.8 | 114,199 | Free + IAP | ||
| 5 | S | 93.3 | 4.6 | 26,029 | Free + IAP | ||
| 6 | S | 92.7 | 4.7 | 7,428 | Free + IAP | ||
| 7 |  CalConvert: Currency ConverterMost recently updated | A | 90.0 | 4.4 | 200,411 | Free + IAP | |
| 8 | A | 88.4 | 4.7 | 2,642 | Free + IAP | ||
| 9 | A | 87.8 | 4.6 | 30,487 | Free + IAP | ||
| 10 | A | 86.8 | 4.6 | 7,898 | Free download | ||
| 11 |  Unit Converter - Best Unit AppMost rated | A | 86.5 | 4.8 | 403,031 | Free + IAP | |
| 12 | B | 76.6 | 4.6 | 85,091 | Free download | ||
| 13 | C | 69.6 | 4.8 | 12,600 | $9.99 | ||
| 14 | C | 63.5 | 4.7 | 4,643 | Free + IAP | ||
| 15 | C | 62.2 | 4.7 | 3,370 | Free + IAP | ||
| 16 | C | 61.5 | 4.8 | 14,092 | $19.99 | ||
| 17 |  Units Converter & Calculatorprovisional | C | 60.0 | 4.7 | 32 | Free + IAP | |
| 18 |  Measure Master Pro Calculatorprovisional | D | 59.5 | 4.8 | 4,696 | Free + IAP | |
| 19 | D | 57.5 | 4.7 | 2,860 | Free + IAP |
New in the last 30 days
Questions people ask
What is the best unit conversion app for iPhone?
Unit Converter - Convert all, S tier, ranked #1 of 19, rated 4.6 by 67,673 people.
Which unit conversion apps are free?
17 of 19 are free to download: Unit Converter - Convert all (S), Metric Conversion tool (S), Conversion Calculator Plus (S), GlobeConvert Currency & Units (S) and more. 14 of them sell in-app purchases. 3 report no in-app purchases.
Which unit conversion app has the best App Store rating?
Measure Master Pro Calculator at 4.8 from 4,696 ratings.
How many unit conversion apps reach S or A tier?
11 of 19.