Calculators usable in dim light


I work at a computer most of the day and I like keeping the lighting in the office pretty dim.

I will often pick up a calculator to do a quick calculation and inevitably I have to turn up the desk lamp and sit up so that I can read the LCD. And my aging eyes don't help the situation.

I have a variety of calculators but all of them have LCD displays that are hard to see in poor light, with the exception of my TI-55 whose keyboard is too annoying for regular use (and the display isn't the best either), and an old Sharp with a fluorescent green display that doesn't have the functionality I need.

I would like to buy a handheld calculator which is easy to see in dim light - meaning LED or fluorescent I assume. I prefer RPN but as long as it has the trignonometric functions (and supports operator precedence) I'd be happy with anything. Although some level of programmability would be truly helpful.

I have read about all sorts of calculators but one thing that descriptions and photographs don't really convey very well are the attributes of the displays.

I know that not all LED displays were equal and since my reason for getting this calculator would be solely for usability in dim lighting, I thought I would throw it out to the group here for advice:

Which of the LED HP calculators had the most readable displays? Are there other scientific handhelds that would serve better (I do like the old fluorescent displays)

Edited: 8 Mar 2013, 4:50 p.m.


IMHO, by far the most readable calculators in dim (or no) light are the Casio fx-9860g series with back-lit displays It would be nice if they had back-lit keys too, but you can generally see the keys in the dark from the display light on the Slim model.


It didn't even occur to me that some of the newer calculators have backlit displays. Thanks for the advice.


Agreed. The fx-9860g Slim really does have an outstanding screen in nearly any light, and the folding design means you'll probably be able to get enough backlight spilling on the keys to read them as well. It's a pretty speedy machine, if you don't mind the fact that it isn't RPN/RPL.


Try the fx9860g RPN apps written by a couple of the regulars on this forum:

Hugh Steers


Nigel Dowrick


First of all, thanks for the recommendations everyone.

I did not see a Slim version for sale, so I ordered the newer model.

This new info about the RPN apps is exciting. Does it work on the newer models? Or will I have to find a Slim?


Yeah, it looks like Casio stopped making the "slim" some time ago. My guess is that the RPN programs will work on the current models but you'll need to check with the program authors (or someone else here might know).


Of course, the HP-97 has easily readable LEDs along with only two functions per key and a built-in printer. For desktop use, it's a fine machine. Card read/write programming as well. Due to the many keys, only one shift key and larger labels, it may well be easier to see what key to press in low light than many others.

While not backlit, the large segmented numbers of the HP-41 and WP 34S may serve in a fairly low light location as well. Both have excellent high contrast LCDs that are easy on the eyes.

When driving up California's Interstate 5 in the wee hours back circa 1978, I'd often program my HP-67 by feel in the dark to stay alert during the 700+km overnight trips. Only the display was visible for seeing the results of a program. Knowing all four functions on every key by feel helped but I don't recommend pushing use *that* hard...


I wonder if the anti-texting-while-driving laws these days would cover your programming while driving...

Although the 97 is tempting, it just is not practical for me, given the way that I tend to use a calculator.

Since I have never seen a 97 in person, I am curious: what size are the LEDs compared to the handheld ones?

I do have a WP-34S and I guess my lighting conditions are a bit darker than most because I have a pretty hard time reading it at my office. Of the LCD calculators I have, I find the HP-15CLE the easiest to work with it. Keys are nicely spaced and the LCD screen is a bit more readable than the others. Now if it was backlit - that would make me very happy.


How about adding a little LED (plus a shield) for lighting the keyboard? If you've got a WP 34S with Harald's USB board, you can power the calc and the LED via USB - and USB supplies should be found everywhere nowadays. Just speculating but sounds viable to me.



Casio Prizm, fx-9860g series with the backlit panel

TI nSpire CX has a nice lit display too

I can't think of an HP with backlit panels for the moment.

Edited: 9 Mar 2013, 1:09 p.m.

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