# William Hackett App vs Sling Load Calc

The clearest difference is in-app purchases: William Hackett App at none against Sling Load Calc's 4. William Hackett App also leads on iOS requirement (12.2 vs 15.0). Sling Load Calc's advantage is update cadence (every 2 weeks vs every 4 months). On price, ads and device support there is nothing between them.

Both are free to download. Sling Load Calc sells 4 in-app purchases, starting at $1.99 per month. William Hackett App asks for nothing beyond the download.

William Hackett App ships an update every 4 months, Sling Load Calc every 2 weeks. The most recent releases landed on September 10, 2026 and August 31, 2026 respectively.

## The numbers

| Metric | William Hackett App | Sling Load Calc |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (4 ratings)](https://appshunter.io/ios/app/sling-load-calc/id6741319888/reviews)** |
| Number of ratings | — | **4** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 weeks** |
| Monetization | — | Freemium |
| Size | 124 MB | 111 MB |
| Requires iOS | **12.2** | 15.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Lazy Grace Limited](https://appshunter.io/developer/1591406593) | [Prakash Solanki](https://appshunter.io/developer/1704788507) |

## What reviewers say

### William Hackett App

[App page](https://appshunter.io/ios/app/william-hackett-app/id1073572596)

**In-app purchases:** none


### Sling Load Calc

[App page](https://appshunter.io/ios/app/sling-load-calc/id6741319888)

This app provides precise calculations for sling tension, length, and angle, essential for safe and efficient lifting operations. It's designed for professionals in heavy lifting industries, offering detailed reports and supporting various rigging configurations.

**Highlights:** Accurate sling tension calculations, Support for vertical and multi-sling loads, Easy-to-use interface, Detailed load and tension reports, Choice of measurement systems, Ensures safety standard compliance

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 1 month plan | $1.99 | per month |
| Special 1 Year Plan | $9.99 | per year |
| Rigging Cal Pro | $14.99 | per year |
| Yearly Pro Plan | $14.99 | per year |


## Frequently asked questions

### Is William Hackett App free?

William Hackett App is free to download, with no in-app purchases.

### Is Sling Load Calc free?

Sling Load Calc is free to download, with in-app purchases available.

### Do William Hackett App or Sling Load Calc have ads?

Neither William Hackett App nor Sling Load Calc shows ads.

### Which is updated more often, William Hackett App or Sling Load Calc?

William Hackett App ships an update every 4 months, and Sling Load Calc every 2 weeks. Most recently, William Hackett App was updated on September 10, 2026 and Sling Load Calc on August 31, 2026.

---

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