HP 49g+ unit conversion problem


Much to my dismay, several years ago I had to bid farewell to my 48SX calculator as it bit the dust - nothing would resurrect it. Some time later, I decided to purchase a new calculator and ended up buying the 49 g+, as the 48SX was not available (at least, not affordably at the time). Until today, the calculator was a paperweight but I decided today to use it to do some quick and easy unit conversions. Ha! As if! I must say, based on my experience with it when I first purchased it and my experience today, that I detest the HP 49g+. With the 48SX, unit conversion was so simple that even though my calculator broke years ago I still remember that it was an easy process.

Since the conversion wasn’t intuitively obvious with this 49 g+, I looked online for assistance. I found some in archives from this site.

One method posted: 1: press right-shift than units. Press next and choose mass,F1. 2: press Kg,F1. The beep sounds and the box 'Error Too Few Arguments' appears on the screen. Just press on/cancel and the box disappears, leaving 1._kg on the stack. 3: press left-shift,then choose g from the menu,F2. Kg is now converted to grams

Here’s another: 1 right shift minus to place an underline after the one, (press * on 48) right shift 6 to access the units menu f6 for speed units, (press e on 48) f6 again, to place knot after 1_, (press f on 48) ENTER left shift mpg to convert to mph

The problem is that when I press left shift I get NO menu. None. What the heck? With the 48SX, I was able to select the units I wanted converted from and then select (in the “menu” across the bottom of the screen) the units I wanted it converted TO without complicated keystrokes or voodoo.

Don’t get me started on the online user’s guide; it’s a joke regarding what I need from it.

So here’s the gist: I want to convert several data points from psi to MPa or vice versa. Let’s say I want to convert 18,500 psi to MPa. It appears I’ll have to convert to Pa and then just take it to MPa from there - no problem. It’s getting from psi to Pa that is the problem.

So I start: 18500 right shift 6, 11, ok, 4, ok (yields 18500_psi in stack)

Now based on what I’ve read before, left (green) shift should give me a menu, right? WRONG!

So, how DO I convert from psi to Pa, short of pulling out my pad and pencil and books and do it manually? After all, that’s why I bought the blasted calculator - to save some time and effort, not add to it!


Turn on RPN mode if not already, turn off exact mode, turn off choose menus (system flag 117 if memory serves).

-117 CF (or it might be -117 SF, I don't have a unit in front of me)

There you go.



FYI, the default is flag -117 cleared, which gives you pull-down menus. To get the soft menus on the top row keys, flag -117 must be set. At this point the HP 49g+ will behave just like the HP 48SX, which only had soft menus. That is how I have my HP 50g configured. This is documented in the AUM, however, you have to dig around to find it.


Hi, guys;

just to add a little bit more info, with [MODE][FLAGS][^] (up-arrow), you'll find flag 117 and current selection:

checked (set): Soft Menu

unchecked (cleared): Choose boxes


Luiz (Brazil)

Edited: 2 Oct 2009, 12:47 p.m.


Thank you! This did help. Calculater was already set to RPN and exact; it was the boxes issue in my case. Thanks again!


Almost any thing that the RPL(N)-only HP48SX/GX can do, the HP49g+/HP50g set for RPL(N) mode can do better and faster, using essentially the same technique. Finding something that is behaving starkly different between the these machines is usually a good sign that some significant optional setup differences exist (provided by the greater versatility of the HP49g+/HP50g), as has been pointed out already.

Some differences are really subtle, such as the possibility of significantly reduced execution speed of an HP49g+/HP50g program that unnecessarily uses binary integers (BINTS, integers displayed without a radix point). On the HP48-series, there's no significance to an integer displayed within a program with or without a radix point. On the HP49g+/HP50g, there definitely is.

Another feature that the HP48-series lacks is an exact versus approximate mode, and of course the algebraic mode option.

The HP50g became overall my favorite HP of the many that I've used since 1972, just edging out my beloved HP42S. I have owned an HP48SX for 18 years, and two GX units for 13. I disliked their slow speed, horrible LCD, misplaced ENTER key (should always be in line with the *, /, +, - keys), firmware that couldn't be revised, and low contrast micro-labeled keyboard. If you have a late HP49g+ with a decent keyboard, use it and you may develope a real appreciation for it.


Hi T.M. You can find a training module titled "Working with Units" at the following web site:

Link to Training Modules

I hope that this helps.




Don’t get me started on the online user’s guide; it’s a joke regarding what I need from it.

Try using the User's Guide located on the CD or available for download from HP's website. It's a GREATLY expanded version of the User's Manual that comes with the calculator.

I recently broke down and printed a copy. Using the laser printer at work, I printed it 2-up and double sided for 4 pages per sheet of paper. Then I took it to Staples and had them put a spiral binding on it. Since their spiral bindings can only do about an inch of paper, I split it into chapters 1-12 and 13-end. I copied the title page and table of contents so I could put those in each volume. Total cost for binding and vinyl covers: $7.

Now, hopeless nerd that I am, I'm reading the manual for fun....


the almighty mantra:



Cheers from another hopeless nerd, who printed it all in original size: two volumes, almost 900 pages total. And is also reading it!


Luiz (Brazil)

Edited: 2 Oct 2009, 11:44 p.m.


I used to sell digital meters. Customers would approach me in conspiratorial tones, is there some something special we need to work on these machines? Yes, when all else fails read the book. I have this stack of books on my table that aren't going to be read. At 81 I still have a full deck, but I don't have the ambition anymore. Sam


I printed out the 653 page Advanced User's Reference Manual at four pages per one side of a 8.5x11 inch sheet, both sides (eight pages per sheet). The result is very compact at 82 pages long and it is quite usable (as long as I have my reading glasses).

I hate reading stuff from a computer screen.

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