# Slide Rule vs Solar Panel Calculator Plus

The clearest difference is review sentiment: Slide Rule at 75% against Solar Panel Calculator Plus's 25%. Slide Rule also leads on price ($0.99 vs $2.99). Solar Panel Calculator Plus's advantage is rating (3.3 vs 1.0) and ratings volume (23 vs 1). On update cadence, ads, in-app purchases and monetization model there is nothing between them.

Slide Rule costs $0.99 and Solar Panel Calculator Plus $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Solar Panel Calculator Plus holds the better App Store score, 3.3 against 1.0. That said, the two scores are not equally well evidenced: Solar Panel Calculator Plus has 23 ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 75% of Slide Rule's written reviews are positive against 25% of Solar Panel Calculator Plus's, so the app with the better star average is not the one people write more warmly about.

Slide Rule ships an update every 29 months, Solar Panel Calculator Plus every 47 months. The most recent releases landed on September 21, 2026 and August 22, 2026 respectively.

## The numbers

| Metric | Slide Rule | Solar Panel Calculator Plus |
| --- | --- | --- |
| Price | **$0.99** | $2.99 |
| Rating | [1.0 (1 ratings)](https://appshunter.io/ios/app/slide-rule/id288454455/reviews) | **[3.3 (23 ratings)](https://appshunter.io/ios/app/solar-panel-calculator-plus/id1358184660/reviews)** |
| Number of ratings | 1 | **23** |
| Positive reviews | **75.0% of reviews** | 25.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 29 months** | Every 47 months |
| Monetization | Paid | Paid |
| Size | 3 MB | 8 MB |
| Requires iOS | 17.0 | **12.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Masayuki Akamatsu](https://appshunter.io/developer/284722836) | [Nitrio](https://appshunter.io/developer/321121189) |

## What reviewers say

### Slide Rule

[App page](https://appshunter.io/ios/app/slide-rule/id288454455)

Simulates a mechanical analog computer for scientific and engineering calculations. Perform multiplication, division, roots, and trigonometric functions with a digital slide rule.

**Highlights:** Multiplication and division, Square and cube roots, Trigonometry functions, Logarithm calculations, Digital slide rule simulation, Mechanical analog computer

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

**In-app purchases:** none


### Solar Panel Calculator Plus

[App page](https://appshunter.io/ios/app/solar-panel-calculator-plus/id1358184660)

Calculate custom off-grid solar home power systems. Determine the exact number of solar panels and battery capacity needed for your energy usage. Helps plan system size, inverter requirements, and battery bank specifications.

**Highlights:** Calculate solar panel requirements, Determine battery capacity, Calculate inverter size, Estimate daily energy usage, Plan days of autonomy, Optimize battery life calculations

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

**In-app purchases:** none


## Frequently asked questions

### Is Slide Rule free?

Slide Rule costs $0.99, with no in-app purchases.

### Is Solar Panel Calculator Plus free?

Solar Panel Calculator Plus costs $2.99, with no in-app purchases.

### Which has better reviews, Slide Rule or Solar Panel Calculator Plus?

Solar Panel Calculator Plus is rated higher. Slide Rule averages 1.0 out of 5 from 1 ratings, while Solar Panel Calculator Plus averages 3.3 from 23 ratings.

### Do Slide Rule or Solar Panel Calculator Plus have ads?

Neither Slide Rule nor Solar Panel Calculator Plus shows ads.

### Which is updated more often, Slide Rule or Solar Panel Calculator Plus?

Slide Rule ships an update every 29 months, and Solar Panel Calculator Plus every 47 months. Most recently, Slide Rule was updated on September 21, 2026 and Solar Panel Calculator Plus on August 22, 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.*