# 100cm Ruler vs Rainfall Calculator

The clearest difference is price: 100cm Ruler at Free against Rainfall Calculator's $2.99. 100cm Ruler also leads on update cadence (every 3 months vs every 29 months). Rainfall Calculator's advantage is rating (5.0 vs 4.0) and in-app purchases (none vs 1). On ratings volume, ads, device support and iOS requirement there is nothing between them.

100cm Ruler is free to download; Rainfall Calculator costs $2.99 up front. 100cm Ruler sells 1 one-off in-app purchase. Rainfall Calculator asks for nothing beyond the download.

Rainfall Calculator holds the better App Store score, 5.0 against 4.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

100cm Ruler ships an update every 3 months, Rainfall Calculator every 29 months. The most recent releases landed on October 5, 2026 and September 28, 2026 respectively.

## The numbers

| Metric | 100cm Ruler | Rainfall Calculator |
| --- | --- | --- |
| Price | **Free** | $2.99 |
| Rating | [4.0 (1 ratings)](https://appshunter.io/ios/app/100cm-ruler/id982815744/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/rainfall-calculator/id1446150880/reviews)** |
| Number of ratings | 1 | 1 |
| Positive reviews | 45.1% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 months** | Every 29 months |
| Monetization | **Free with in-app purchases** | Paid |
| Size | 62 MB | 1 MB |
| Requires iOS | **12.0** | 13 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [ZOOMO Inc.](https://appshunter.io/developer/490112424) | [Nitrio](https://appshunter.io/developer/321121189) |

## What reviewers say

### 100cm Ruler

[App page](https://appshunter.io/ios/app/100cm-ruler/id982815744)

This app provides a digital ruler for measuring the length and diameter of small objects directly on your device. It features a millimeter scale and allows for easy sliding to measure.

**Highlights:** Digital ruler functionality, Millimeter scale, Diameter measurement, Screen sliding for measurement, Ad removal option

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove ADS | $1.99 | one-time |


### Rainfall Calculator

[App page](https://appshunter.io/ios/app/rainfall-calculator/id1446150880)

Calculate potential rainwater harvest volume and cost savings. This tool helps determine annual water collection capacity based on rainfall and roof area, recommending optimal tank sizes for efficient water storage. It also allows for cost-saving analysis by comparing harvested water to mains water prices.

**Highlights:** Instant rainwater calculation, Cost savings evaluation, Minimum tank size recommendation, Supports various input units, Formula references included, Results copyable to other apps

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is 100cm Ruler free?

100cm Ruler is free to download, with in-app purchases available.

### Is Rainfall Calculator free?

Rainfall Calculator costs $2.99, with no in-app purchases.

### Which has better reviews, 100cm Ruler or Rainfall Calculator?

Rainfall Calculator is rated higher. 100cm Ruler averages 4.0 out of 5 from 1 ratings, while Rainfall Calculator averages 5.0 from 1 ratings.

### Do 100cm Ruler or Rainfall Calculator have ads?

Neither 100cm Ruler nor Rainfall Calculator shows ads.

### Which is updated more often, 100cm Ruler or Rainfall Calculator?

100cm Ruler ships an update every 3 months, and Rainfall Calculator every 29 months. Most recently, 100cm Ruler was updated on October 5, 2026 and Rainfall Calculator on September 28, 2026.

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