# PerfectFit® Ring Sizer vs One OS

The clearest difference is review sentiment: One OS at 100% against PerfectFit® Ring Sizer's 0%. One OS also leads on price (Free vs $0.99) and iOS requirement (14.0 vs 16.0). PerfectFit® Ring Sizer's advantage is chart position (#198 vs unranked). On update cadence, ads, in-app purchases and device support there is nothing between them.

One OS is free to download; PerfectFit® Ring Sizer costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

PerfectFit® Ring Sizer ships an update every 2 months, One OS every 3 months. The most recent releases landed on October 14, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | PerfectFit® Ring Sizer | One OS |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | **[2.5 (2 ratings)](https://appshunter.io/ios/app/perfectfit-ring-sizer/id1525643957/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 0.0% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 3 months |
| Monetization | Paid | **Free** |
| Best chart rank | **#198** | — |
| Size | 6 MB | 155 MB |
| Requires iOS | 16.0 | **14.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Radius Technologies](https://appshunter.io/developer/1452970152) | [Wearatec Inc](https://appshunter.io/developer/1291493037) |

## What reviewers say

### PerfectFit® Ring Sizer

[App page](https://appshunter.io/ios/app/perfectfit-ring-sizer/id1525643957)

**Currently charting:** #198 Top Paid · Lifestyle (US App Store)

Accurately measure your ring size for any finger using advanced technology. This app eliminates the need for manual fittings and seamlessly integrates with online jewelry stores, solving sizing issues for e-commerce.

**Highlights:** Accurate to 1/8 sizes, Works on any mobile device, International sizing conversion, E-commerce integration, Customizable skinning

**In-app purchases:** none


### One OS

[App page](https://appshunter.io/ios/app/one-os/id6472438941)

This app transforms luxury watches into smart companions by integrating health monitoring, contactless payments, and access to connected luxury experiences. Manage multiple devices, secure your data, and add payment cards, keys, and access cards to your wearable.

**Highlights:** Health monitoring and fitness tracking, Contactless payments via NFC, Manage multiple connected watches, Securely store payment cards and access keys, Access connected luxury experiences, Full data control and anonymity

**In-app purchases:** none


## Frequently asked questions

### Is PerfectFit® Ring Sizer free?

PerfectFit® Ring Sizer costs $0.99, with no in-app purchases.

### Is One OS free?

One OS is free to download, with no in-app purchases.

### Do PerfectFit® Ring Sizer or One OS have ads?

Neither PerfectFit® Ring Sizer nor One OS shows ads.

### Which is updated more often, PerfectFit® Ring Sizer or One OS?

PerfectFit® Ring Sizer ships an update every 2 months, and One OS every 3 months. Most recently, PerfectFit® Ring Sizer was updated on October 14, 2026 and One OS on October 10, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*