# DB40X — High-precision RPL calculator

> High-precision scientific calculator with RPN, arbitrary precision, and advanced math functions. (iPhone/iPad app by Christophe de Dinechin.)

- Source: https://appshunter.io/ios/app/db40x/id6624315901 (this page in markdown: same URL + `.md`)
- Developer: [Christophe de Dinechin](https://appshunter.io/developer/1761608161)
- Category: Productivity, Education
- Price: Free
- Rating: 4.71/5 from 7 App Store ratings · 3 written reviews indexed
- Age rating: 4+
- Requires: iOS 14.0 · 7 MB
- Languages: English
- Released: 2024-08-21
- Data updated: 2026-06-04
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/db40x/id6624315901/reviews.md

## What is DB40X?

DB40X is a high-precision scientific calculator compatible with DB48X and inspired by the legendary HP48 series from Hewlett-Packard.
It is not an emulator, but a redesign from scratch, which is faster, and delivers never seen before capabilities like computations in arbitrary precision.

Like the original HP48, DB40X supports an unlimited stack, RPN and algebraic operations, complex numbers, based numbers, vectors, matrices, text, symbolic computations, numerical solving and integration, graphing and plotting, statistics, engineering units, and well over 1000 built-in functions. DB40X adds several HP50G capabilities, including a library of equations and constants covering mathematics, physics or chemistry.

Using modern technologies, DB40X goes well beyond the original HP48 in many ways:
- It is significantly faster, uses less memory, and features a higher-resolution 240x400 pixels graphical display.
- Integer and decimal values can have an arbitrarily large number of digits, so you can compute log(pi) with 200 digits in a few keystrokes.
- The six function keys feature up to three function per key, giving quick access to up to 18 related functions at a time.
- Complex numbers can mix and match polar and rectangular form.
- Symbolic operations extend to complex numbers, vectors and matrices.
- Based numbers can be in any base from 2 to 36, and support any number of bits, making it easy to emulate a 23-bit or 512-bit processor.
- Text is represented using Unicode instead of the proprietary HP encoding, facilitating data exchange with the rest of the world.
- Multiple graphs can be distinguished using bitmap patterns.
- Engineering units include all the modern evolutions of the SI system, and can be configured by the user, e.g. to integrate currency units with the exchange rate du jour. Converting between USD/hour and EUR/day has never been so easy!
- A built-in hyperlinked help system documents functions simply by holding the corresponding key, and combine a quick start guide, a user manual and a reference manual.

DB40X will run many user RPL programs as is.
However, since it is not an emulator, it will not run any HP binary object, and notably will not run HP48 games or anything involving system RPL.

Version 0.7.14 is an early-access release. Please consult https://github.com/c3d/db48x/blob/stable/doc/5-Unimplemented.md for a list of HP48 commands that are not yet implemented.
DB40X is part of a family of compatible RPL calculators that include DB48X and DB50X.
DB40X lacks the ability to write programs or data to disk, and RPL programs are limited to 40K.

## Key features

- Arbitrary precision computations
- RPN and algebraic operations
- Complex numbers, vectors, and matrices
- Graphing and plotting
- Engineering units and conversions
- Hyperlinked help system

## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/db40x/id6624315901/reviews.md

### 3/5 — Nice but too cluttered looking

*2026-05-09*

I have pretty much every HP emulation that has shown up on the App Store and I still have numerous real ones including a 15, a 16, a 34, a 48, a 67 and a 97 and two from Swiss Micro including their 42. My introduction to computing was the 25C some fifty years ago.

While this new 40 has some incredible functionality, cosmetically it looks far too cluttered. Maybe it’s the wrong fonts, or the fonts are too big and though it’s clearly very powerful, it loses  the HP realism, which frankly is a big reason to collect them.

I would love to see an update that addresses the cosmetics.

### 5/5 — Cool program

*2025-09-13*

If you’ve used the hp48, 28, or 50g then do yourself a favor and try it.  Much more advanced but faithful to the vision for the 48sx.  This is a much more appropriate successor to the hp48sx than the 50g was.

### 5/5 — Amazing

*2024-09-22*

This is an incredible calculator whether or not you have used an HP48. It does everything and is easy and intuitive to use, and is getting regular updates. Amazing work!

## Frequently asked questions about DB40X

### What is DB40X?

DB40X is a high-precision scientific calculator designed from scratch, inspired by the HP48 series. It offers advanced features like arbitrary precision computations, complex numbers, matrices, and graphing, with over 1000 built-in functions.

### Does DB40X support RPN?

Yes, DB40X fully supports Reverse Polish Notation (RPN) operations, along with algebraic operations, catering to users familiar with this input method.

### Can DB40X perform calculations with arbitrary precision?

Yes, DB40X allows for computations with an arbitrarily large number of digits for integer and decimal values, enabling high-precision calculations like log(pi) with 200 digits.

### What types of mathematical objects does DB40X support?

DB40X supports complex numbers (in polar and rectangular forms), vectors, matrices, text, symbolic computations, numerical solving, integration, graphing, and statistics.

### Is DB40X compatible with HP48 programs?

DB40X can run many user RPL programs as is, but it is not an emulator and will not run HP binary objects or system RPL, including HP48 games.

### How is the help system in DB40X?

DB40X features a built-in hyperlinked help system that documents functions by holding the corresponding key. It combines a quick start guide, user manual, and reference manual for easy access to information.

### What devices is DB40X available on?

DB40X is available for iPhone, iPad, and iPod, running on iOS devices.

### How often is DB40X updated?

The latest version is 0.9.17, last updated on March 10, 2026. Version 0.7.14 was an early-access release, indicating ongoing development and updates.

## Version history (last 5 releases)

### 0.9.19 — 2026-05-25

This release brings an improved constants library with Astronomy and Materials sections, the Quote command, GCD and LCM commands, and several other improvements.

See release notes (https://github.com/c3d/db48x/releases/tag/v0.9.19) for details.

### 0.9.18 — 2026-04-17

New features:
* Implement the `Chuck` command
* Make `xq` recognize more patterns during simplification
* List the menus in the help file
* Support for tables in the help file
* `ListRecursionDepth` setting for `map`, `reduce`, `filter`

Bug fixes:
* Fix incorrect evaluation of constants during simplification

Improvements:
* Improve solver shuffle around singularities and errors

### 0.9.17 — 2026-03-10

Extended support for quotients, algebraic notation for array/list indexing (e.g. 'L(1;2)' ), copy-paste support.

### 0.9.16 — 2026-03-07

0.9.16 adds a number of new features and bug fixes, detailed in the release notes in the built-in help file. The primary new features include: prime numbers and factorization, displaying keyboard shortcuts in the built-in help, extended rational approximation (→Qπ).

### 0.9.14 — 2025-11-10

Immediate rendering for off-screen graphics, bug fixes.

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## More apps by Christophe de Dinechin

- [DB48X](https://appshunter.io/ios/app/db48x/id6615086535)
- [DB50X](https://appshunter.io/ios/app/db50x/id6625971367)

All apps by Christophe de Dinechin: https://appshunter.io/developer/1761608161

## Related topics

[db40x](https://appshunter.io/ios/topics/db40x) · [db48x](https://appshunter.io/ios/topics/db48x) · [hp 48gx](https://appshunter.io/ios/topics/hp-48gx) · [hp48gx](https://appshunter.io/ios/topics/hp48gx)

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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 2026-06-04.*