# Digital Slide Rule

> Digital simulation of historical slide rules with advanced features and a historical slideshow. (iPhone/iPad app by Ace Hoffman.)

- Source: https://appshunter.io/ios/app/digital-slide-rule/id1116881577 (this page in markdown: same URL + `.md`)
- Developer: [Ace Hoffman](https://appshunter.io/developer/704983956)
- Category: Education, Reference
- Price: Free
- Rating: 5.00/5 from 14 App Store ratings · 7 written reviews indexed
- Age rating: 4+
- Requires: iOS 6.0 · 59 MB
- Languages: American English
- Released: 2016-05-25
- Data updated: 2026-06-01
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/digital-slide-rule/id1116881577/reviews.md

## What is Digital Slide Rule?

The slide rule was used for over 400 years as a calculating/estimation tool. Abandoned with the advent of hand-held calculators, computers and smart phones, their elegant simplicity is still a thing of wonderment. This program replicates the most common types of slide rules: Straight, circular, spiral and cylindrical. Dozens of scales are included and numerous features that could never exist on a physical slide rule are also included, such as color options, numeric displays of the values under the hairlines, and so on.
Slide rules were used to go to the moon and to build bridges, skyscrapers, tunnels, aqueducts and nearly everything else. Slide rules were simple to use and accurate enough for most occasions.

Also, note that this program is processor-intensive and with heavy use, will probably drain your battery quickly. Every effort has been make the program efficient, but nevertheless, some functions take a few moments to occur, including initial load, which can take three or four seconds, or perhaps a little longer. Nearly 30,000 "nibs" are created during this time, as well as over 3,000 labels, so please be a little patient! Because of all the detail, it looks best and runs best on a large-format machine such as a tablet. Also because of all the detail, the 30-loop spiral slide rule converts to a low-rez "bitmap data image" while you move it, then back to a "vector based image" as soon as you release.

Includes a brief side show slide show of famous and interesting slide rules, most of which are in the author's collection. Two are public-domain photographs of antique slide rules.

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Notes on usage: Program features include "two-finger pinch/zoom." Slide rule slide show images can also be rotated. Enlarge an image by double-tapping in the same place. Tapping three times in the same place will return the program to the home position. Tapping four times will bring up an intro-screen message which requires tapping anywhere to remove.

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This program was first released in 2016 and is the product of a lifelong love of numbers (and 30+ years of programming experience!).

Special thanks to the Oughtred Society for their member's invaluable help in evaluating the earliest versions of this program.

## Key features

- Simulates straight, circular, spiral, and cylindrical slide rules
- Dozens of scales included
- Color options and numeric value displays
- Includes a slideshow of famous slide rules
- Supports two-finger pinch/zoom and image rotation

## Recent user reviews (7 of 7)

All indexed reviews: https://appshunter.io/ios/app/digital-slide-rule/id1116881577/reviews.md

### 5/5 — Brilliant!!!

*2024-05-11*

Well done. Thank you.

### 4/5 — Excellent app

*2023-04-02, version 4.06.08*

Only, resizing and moving the ruler across the screen is very difficult

### 5/5 — Absolutely Beautiful

*2022-10-14*

Beautiful simulation of an actual slide rule with many variations of older slide rules.

### 5/5 — An amazing app!

*2019-08-22, version 4.06.08*

As a slide rule collector I was sceptical that such a complicated device could be modelled with such precision. The inclusion of scales devised after the end of the slide rule’s demise in 1974 is quite remarkable. There are so many wonderful features. I dont find battery drain to be a problem. The only very minor improvement would be to correct a few unusual scale divisions 
(eg between 2 and 5x10^-5 on the LL03 scale, 2 and 3 x 10^4 on LL3 scale, and most notably between 2 and 3 on the A scale where divisions increase in 0.25 steps instead of 0.2). However these errors do not change the fact that this is a brilliant app.

### 5/5 — Excellent — This program really surprised me.

*2019-04-30*

The slide rules are rendered realistically — you get a sense of what it was like to use them. Plus I also love that the text and the slide rules are integrated.  Great job!

### 5/5 — Calculate without using buttons!

*2016-09-29*

This is awesome an App and it will help introduce the slide rule to those that were not required to use them prior to electric calculators being developed.
+ Using this App in landscape mode really makes it wonderful!

### 5/5 — Digital Sliderule

*2016-06-09*

This is way cool. I love the variety. Just needs to have the pay for add free version.

## Frequently asked questions about Digital Slide Rule

### What types of slide rules does Digital Slide Rule simulate?

Digital Slide Rule simulates the most common types of slide rules, including straight, circular, spiral, and cylindrical models. It offers dozens of scales and advanced features not possible on physical instruments.

### Does Digital Slide Rule have ads?

No, Digital Slide Rule does not contain advertisements. It is a completely ad-free experience for users.

### What are the system requirements for Digital Slide Rule?

Digital Slide Rule is available on iPhone, iPad, and iPod. The description notes it looks and runs best on large-format machines like tablets due to its detailed graphics.

### How accurate is Digital Slide Rule?

The app replicates slide rules that were historically accurate enough for most occasions, used for complex engineering feats like building bridges and going to the moon. The digital simulation aims to maintain this level of utility.

### How does Digital Slide Rule handle battery usage?

The app is processor-intensive, and heavy use may drain the battery quickly. While efforts have been made to optimize efficiency, some functions, like the initial load, can take a few moments.

### What is the learning curve for Digital Slide Rule?

Slide rules were historically simple to use. This digital version aims to maintain that simplicity while offering enhanced features. The app includes a slideshow to provide historical context.

### When was Digital Slide Rule first released and how often is it updated?

Digital Slide Rule was first released on May 25, 2016. The latest version, 4.06.08, was updated on October 30, 2017, indicating a less frequent update cycle in recent years.

### What is the age rating for Digital Slide Rule?

Digital Slide Rule has an age rating of 4+. This suggests it is suitable for a wide range of users, including younger individuals interested in educational tools.

## Version history (last 5 releases)

### 4.06.08 — 2017-10-30

This app has been updated by Apple to display the Apple Watch app icon.

Faster setup time after program is loaded (as much as 50% faster); streamlined internal processing (especially of Cylindrical Slide Rule); corrected "Display Estimated Hairline Values" for several of the alternate scales.

### 3.30.08 — 2017-07-29

Items can be enlarged separately for faster response times. A rotating fine adjust button added (hold finger over slide or hairline for a few seconds to use). Several add'l old slide rules added, including a circa 1962 Nuclear Bomb Effects Computer. Digital 10-loop spiral added. Many minor enhancements, mostly for speed improvements. Uses occasional interstitials instead of banners, except for the first few minutes when small banners for our other programs are shown.

### 2.56.90 — 2017-04-28

Added 9 new scales designed by Istvan Szalkai
Minimum frame rate now 0.05 f.p.s. for iOS devices. Shortened time before going to minimum frame rate to save battery power.
Improved alignments of nibs at alignment points. Improved alignment of colorized nibs.
All descending scales now colored red.
Animated many scales in opening screen and in slide rule slide show.
Added buttons to rotate scales in slide show.
Added more environment info to settings box, added gear in upper right now brings box up.
Allowed straight slide rule upper and lower hairlines and slides to be moved separately if desired (use lock/unlock button on right lower slide to turn lockstep off/on)
Added display of hairline values when values display active and slide(s) are moved (not just when hairline is moved)
Added animation from Eadweard Muybridge's 1800s photographs when author name in title is clicked.
Other minor fixes.

### 1.74.16 — 2016-10-24

Now includes a learning slide rule with just five scales on it: A, B, C, D and CI, along with instructions for several basic mathematical operations: multiplication, division, squares and square roots.

### 1.72.12 — 2016-05-25

No release notes.

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## More apps by Ace Hoffman

- [Revitavet Infrared Therapy Protocols](https://appshunter.io/ios/app/revitavet-infrared-therapy-protocols/id704983953)
- [Fidget Spinners Galore!](https://appshunter.io/ios/app/fidget-spinners-galore/id1272524745)
- [Animated Antique Posographe](https://appshunter.io/ios/app/animated-antique-posographe/id1488545400)

All apps by Ace Hoffman: https://appshunter.io/developer/704983956

## Related topics

[slide rule](https://appshunter.io/ios/topics/slide-rule) · [digital slide rule](https://appshunter.io/ios/topics/digital-slide-rule) · [smart slide rule](https://appshunter.io/ios/topics/smart-slide-rule) · [pocket slide rule expert](https://appshunter.io/ios/topics/pocket-slide-rule-expert) · [ultimate slide rule](https://appshunter.io/ios/topics/ultimate-slide-rule) · [smalls sliders](https://appshunter.io/ios/topics/smalls-sliders) · [super cool slide rule](https://appshunter.io/ios/topics/super-cool-slide-rule)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-01.*