GO-25 SciRPN simulates the venerable HP-25C Programmable Scientific Calculator. The HP-25C was released in 1976 and sold for a MSRP of $195. Virtually indistinguishable from the real item in operation, GO-25 is a powerful yet simple retro calculator.

•Requires iOS 8.0 or higher
•Copy / Paste
•Shake to clear X
•Programmable with 99 program steps, conditionals, full-speed or single step operation
•Built-in library of sample programs
•iTunes File Sharing
•Swipe-up gesture that displays the stack and memory registers, and the program listing views
•For iPad two finger drag operations for displayed views
•Addition, subtraction, multiplication, division
•Trigonometric functions : sin, cos, tan, sin⁻¹, cos⁻¹, tan⁻¹, degrees, radians or grads
•Rectangular/polar coordinate conversion
•Hours, minutes, seconds to decimal degrees conversion, and vice-versa
•Logarithmic functions : log, 10**x, ln, e**x
•Summation Σ+, mean, standard deviation
•Other functions : Y**x,1/x, √x, π, FRAC, INT, ABS, %
•Display : LED, 10 significant digits (8 + 2 digit exponent in scientific notation), 10-99 to 10+99
•Memory : 4 register stack, stack roll down, X-Y interchange, 10 memory registers with register math
•Optional thousands separator

What's New

Version 2.14

- Update for iOS 12.0.
- Do not raise the stack when using the EEX shortcut immediately after an ENTER.

Ratings and Reviews

4.6 out of 5
11 Ratings
11 Ratings

Amazing Rendition


When the on-off switch on my 25C gave out I got a 32SII.

For those that had a 25C, the faithfulness of this rendition is amazing.

I prefer the 25C emulation to a 42S emulation because it is more Spartan. For those that want more keys to fat-finger (37 instead of 30 is noticeably more crowded) and more programmability (why when for anything serious you have something like Mathematica?) there are at least two emulations of the 42S on the App Store.


The tiny green LEDs, the blue info button, and the fact that the iPhone's status bar are not hidden all distract from the purity of the experience. How about an super-retro mode where all those are gone?

A more evocative app icon? Maybe just 0.00 in red LEDs?

I didn't find either of the keystroke sounds satisfying so I had to turn sounds off. The 25C had a padded yet definite click that I guess is hard to duplicate.

Needs some finger grime and a flaky on/off switch to be like I remember.

A welcome blast from the past


It was December 1975 when I bought my very first HP calculator, an HP-25, at the Harvard Coop for US$199, a cost about US$1,000 in 2014 dollars. It was a great product which got me hooked on RPN. When I saw this app, I bought it for the awake of nostalgia and also as a tool. Let me say that it is totally faithful to the original, except that the original had only 49 (not 99) program steps and lost all memory contents when switched off. Strongly recommended from an old timer who has seen the rest and knows the best.

Jcc3rd RPN user


I've used the SciRPN-25 for about 3 months. The calculator emulates the original HP25c accurately, but with more programmable steps. The panel showing the stack and register content make the calculator easier to use compared to the original. No bugs detected yet. The SciRPN-25 replaced my buggy HP-11c emulator. I've written my own programs including: combinations, permutations, amortization, and linear regression. Highly recommended for those who want to replace their aging or non-working Woodstock class HP calculators: 25, 25c, or 29c. In summary, I love this calculator.


Technology Man IR
17.9 MB
Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
Copyright (©) 2010-2018 Stephen O. Lidie


  • Family Sharing

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