HP · RPN programmable · October 1983 to November 1990

HP-41CX

The 41CX, code name Honeynut, was the last HP-41, launched in October 1983 and sold until November 1990. HP took the 41CV and built in what most owners were buying separately: the Time Module with its clock, calendar, alarms and stopwatch, and the Extended Functions/Memory module with 124 more registers and a text editor. That left all four ports free and gave it over 200 built-in functions, and it still runs every 41C program and module. The alarms can switch the calculator on and run a program, which is how people used 41s to log data unattended. It's the 41 most collectors want first, so it's also the one most likely to be a clone, a 41CL conversion or a CV sold as a CX.

Good forEngineering Surveying and real estate Collecting

HP-41CX (Fullnut)HP-41CX (Halfnut, black frame under the display)

Spec at a glance

Maker: HP
Type: RPN programmable
Launched: 1983
Made: October 1983 to November 1990
Entry: RPN
Display: LCD
Programmable: Yes
Memory: 319 registers plus 124 registers of extended memory
Built in: Time Module, Extended Functions/Memory and a text editor
Display: 12-character alphanumeric LCD (14-segment characters plus punctuation)
Ports: Four plug-in ports, all free
Power: Four N cells, or the HP 82120A rechargeable pack
Also listed as: HP 41CX, HP41CX
Typical eBay ask (Oct 15, 2026): $280–$460

Bench check

Power, memory, display and keys

Battery and power: Four N cells or the 82120A NiCd pack. The clock keeps drawing power with the calculator off, and HP notes the clock and stopwatch displays won't run with the BAT warning lit. Leaked batteries do the same damage here as on any 41, so check the battery bay first.
Memory: Continuous Memory keeps the 319 main registers, the 124 extended-memory registers, the clock, the alarms and the current file while it's off. Extended memory grows with HP 82181A X Memory modules.
Display: The 41's 12-character alphanumeric LCD. A Halfnut CX, the later build, has a black frame under the display glass and puts the timer and extended memory in one chip.
Keys: One gold shift key and ALPHA. Ask about lockups, which HP traces to poor contacts.
Cards, ports and modules: All four ports are free, and the Time Module and the 82180A Extended Functions/Memory module are already built in, so a listing that bundles either one as an extra is selling you something you don't need. The card reader is the separate HP 82104A, which plugs into port 4.
Original, reissue or clone: Functions like CLOCK and EMDIR work with no module plugged in, which only a 41CX does. HP's serial label on the bottom gives the year, week and country. The SwissMicros DM41X runs 41CX software, and a Systemyde 41CL is a new board inside a real HP case, so a CX that runs very fast or lists hundreds of modules is a 41CL.

Should come with it

Port covers on the unused ports
The two-volume owner's manual, and any modules or card reader the listing shows

Check the listing photos against this list, and ask the seller about anything you can’t see. A missing piece should come off the price.

Modules that fit

The plug-in modules we cover for the HP-41CX. Each page says what it adds, what’s already built in and how to check one.

What to check

Battery corrosion and poor contacts cause most dead or locked-up 41s. Listings that bundle a Time Module or X Functions module with a CX are padding the price, since both are built in.

01Battery compartment: Ask for a photo with the battery holder out. Bright contacts with no green or white crust are what you want.
02Real CX: Ask the seller to run CLOCK with no modules plugged in. A 41CX shows the time; a CV just shows NONEXISTENT.
03Display: Ask for a photo of the display with every segment lit. All 12 characters should be complete.
04Keys: Ask whether every key registers once per press. No dead or doubled keys is what you want.
05Clock: Ask whether the clock kept time over a day or two. Within a few seconds a day is what HP's spec allows.
06Bundled modules: Check the photos for a Time or X Functions module in the bundle. Both are built into the CX, so don't pay extra for them.
07Card reader: If an 82104A is included, ask whether it read a card recently. A reader that loads a card cleanly is what you want.
08Real HP: Look for HP's serial label on the bottom near the ports. A DM41X is a modern clone, and a 41CL conversion should be listed as one.

New to old calculators? The condition checklist covers battery corrosion, displays, keys and card readers, and RPN in one hour gets you typing on an HP.

Buying guide

Which one to buy

§ Oct 15, 2026

We'd buy kjupki85's 41CX titled working with its case at $256 delivered, under the $280-460 band, from a 100% seller. There are at least 28 for sale, and plain calculators with a case ask $164-304 delivered, while bundles with pacs, both manual volumes or the original box run $306-495. The CX is the 41 most likely to be a clone or a CV sold as a CX, so ask the seller to run CLOCK with no modules plugged in (a CV just shows NONEXISTENT), and ask for a photo with the battery holder out, since corrosion there eats the flexible circuit behind the ports. Don't pay extra for a bundled Time or X Functions module, since both are built in, and skip the $814 and $914 listings at 2.4 and 2.7 times the $335 median.

Listed now: 28
For parts: 0
Typical ask: $280–$460
Full range: $152–$899

Cheapest
$163.70est. delivered
The lowest delivered 41CX here at $164 with its case, and the photo shows it switched on with text on the display. It isn't titled tested, so ask for CLOCK run with no modules in and a photo of the battery bay.
Hewlett Packard HP 41CX Calculator With Case
View on eBay ↗: Hewlett Packard HP 41CX Calculator With Case$163.70 est. delivered
Best value
$256.47est. delivered
Titled working with its case at $256 delivered, about $80 under the median, from a 100% seller. The photo shows only the calculator, so ask to see the case and the open battery bay.
Hewlett Packard HP 41CX Scientific Calculator w/Case Vintage Calc working
View on eBay ↗: Hewlett Packard HP 41CX Scientific Calculator w/Case Vintage Calc working$256.47 est. delivered
Collector's pick
$354.67est. delivered
A Fullnut CX, the earlier build without the black frame under the display, with its case, manuals and the Financial and Surveying pacs at $355 delivered, about the median. It isn't titled tested, so ask for CLOCK run and the display lit.
HP 41CX Fullnut Calculator w/ Case, Manuals, Financial & Surveying PAC ROMs
View on eBay ↗: HP 41CX Fullnut Calculator w/ Case, Manuals, Financial & Surveying PAC ROMs$354.67 est. delivered

Delivered prices include shipping as eBay quoted it to a US address on Oct 15, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.

Snapshot

For sale on eBay

8 of 28 listed

Checked Oct 15, 2026. Some may have sold.

Delivered prices include shipping as eBay quoted it to a US address on Oct 15, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.

Used
- Cheapest
Hewlett Packard HP 41CX Calculator With Case
$163.70est. delivered
$152.00 + $11.70 shipping
Buy It Now$152.00
Good buy
With case. Photo shows it on with text on the display; no test claim.
Seller: quark1967
100% positive
View on eBay ↗: Hewlett Packard HP 41CX Calculator With Case
Used
- Best value
Hewlett Packard HP 41CX Scientific Calculator w/Case Vintage Calc working
$256.47est. delivered
$250.00 + $6.47 shipping
Buy It Now$250.00
Offers accepted
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Good buy
Titled working, with case.
Seller: kjupki85
100% positive
View on eBay ↗: Hewlett Packard HP 41CX Scientific Calculator w/Case Vintage Calc working
Used
- Collector's pick
HP 41CX Fullnut Calculator w/ Case, Manuals, Financial & Surveying PAC ROMs
$354.67est. delivered
$340.00 + $14.67 shipping
Buy It Now$340.00
Offers accepted
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Good buy
Titled Fullnut, with case, manuals, and Financial and Surveying pacs. No test claim.
Seller: alpinecircuitco
100% positive
View on eBay ↗: HP 41CX Fullnut Calculator w/ Case, Manuals, Financial & Surveying PAC ROMs
Used
Hewlett-Packard HP 41CX Scientific Calculator w/Case - Halfnut (2834S)
$266.50est. delivered
$250.00 + $16.50 shipping
Buy It Now$250.00
Offers accepted
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled Halfnut, with case. Serial 2834S, 1988, Singapore. No test claim.
Seller: husmus
100% positive
View on eBay ↗: Hewlett-Packard HP 41CX Scientific Calculator w/Case - Halfnut (2834S)
Used
HP 41CX Calculator With Case and Surveying I and Navigation Modules - Works
$306.09est. delivered
$299.00 + $7.09 shipping
Buy It Now$299.00
Offers accepted
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled works, with case and Surveying I and Navigation modules.
Seller: belethors_general_g00ds
100% positive
View on eBay ↗: HP 41CX Calculator With Case and Surveying I and Navigation Modules - Works
Used
HP-41CX Calculator With Case Original Box Manuals New Batteries
$417.20est. delivered
$400.00 + $17.20 shipping
Buy It Now$400.00
Offers accepted
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled with case, original box, manuals and new batteries. No test claim.
Seller: curatedtreasurespnw
99.7% positive
View on eBay ↗: HP-41CX Calculator With Case Original Box Manuals New Batteries
Used
- Check the seller
- Priced high
Hewlett Packard HP 41CX Calculator Having HP Hard Leather Case and Soft Keyboard
$814.35est. delivered
$799.00 + $15.35 shipping
Buy It Now$799.00
Priced high
Seller feedback 83.3%. Photo shows the calculator alone, at 2.4 times the median.
Seller: ahgmtt
83.3% positive
View on eBay ↗: Hewlett Packard HP 41CX Calculator Having HP Hard Leather Case and Soft Keyboard
Used
- Priced high
Hewlett Packard 41CX Includes Rare Zengrange Module Memory Mudule Plus Case
$914.00est. delivered
$899.00 + $15.00 shipping
Buy It Now$899.00
Offers accepted
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Priced high
Titled with a Zengrange module and a memory module. A CX already has full main memory, so ask which one. About 2.7 times the median.
Seller: rivervalleycouple
100% positive
View on eBay ↗: Hewlett Packard 41CX Includes Rare Zengrange Module Memory Mudule Plus Case

Prices change daily. The live eBay search shows everything listed now, including anything new since Oct 15, 2026.

See every listing on eBay ↗eBay search

Compare with

HP-41CX

HP-41CX (Fullnut)HP-41CX (Halfnut, black frame under the display)

Spec at a glance

Maker

Type

RPN programmable

Launched

1983

Made

October 1983 to November 1990

Entry

RPN

Display

LCD

Programmable

Yes

Memory

319 registers plus 124 registers of extended memory

Built in

Time Module, Extended Functions/Memory and a text editor

Display

12-character alphanumeric LCD (14-segment characters plus punctuation)

Ports

Four plug-in ports, all free

Power

Four N cells, or the HP 82120A rechargeable pack

Also listed as

HP 41CX, HP41CX

Typical eBay ask (Oct 15, 2026)

$280–$460

Power, memory, display and keys

Battery and power

Four N cells or the 82120A NiCd pack. The clock keeps drawing power with the calculator off, and HP notes the clock and stopwatch displays won't run with the BAT warning lit. Leaked batteries do the same damage here as on any 41, so check the battery bay first.

Memory

Continuous Memory keeps the 319 main registers, the 124 extended-memory registers, the clock, the alarms and the current file while it's off. Extended memory grows with HP 82181A X Memory modules.

Display

The 41's 12-character alphanumeric LCD. A Halfnut CX, the later build, has a black frame under the display glass and puts the timer and extended memory in one chip.

Keys

One gold shift key and ALPHA. Ask about lockups, which HP traces to poor contacts.

Cards, ports and modules

All four ports are free, and the Time Module and the 82180A Extended Functions/Memory module are already built in, so a listing that bundles either one as an extra is selling you something you don't need. The card reader is the separate HP 82104A, which plugs into port 4.

Original, reissue or clone

Functions like CLOCK and EMDIR work with no module plugged in, which only a 41CX does. HP's serial label on the bottom gives the year, week and country. The SwissMicros DM41X runs 41CX software, and a Systemyde 41CL is a new board inside a real HP case, so a CX that runs very fast or lists hundreds of modules is a 41CL.

Should come with it

Port covers on the unused ports

The two-volume owner's manual, and any modules or card reader the listing shows

Check the listing photos against this list, and ask the seller about anything you can’t see. A missing piece should come off the price.

What to check

Battery corrosion and poor contacts cause most dead or locked-up 41s. Listings that bundle a Time Module or X Functions module with a CX are padding the price, since both are built in.

01Battery compartment: Ask for a photo with the battery holder out. Bright contacts with no green or white crust are what you want.

02Real CX: Ask the seller to run CLOCK with no modules plugged in. A 41CX shows the time; a CV just shows NONEXISTENT.

03Display: Ask for a photo of the display with every segment lit. All 12 characters should be complete.

04Keys: Ask whether every key registers once per press. No dead or doubled keys is what you want.

05Clock: Ask whether the clock kept time over a day or two. Within a few seconds a day is what HP's spec allows.

06Bundled modules: Check the photos for a Time or X Functions module in the bundle. Both are built into the CX, so don't pay extra for them.

07Card reader: If an 82104A is included, ask whether it read a card recently. A reader that loads a card cleanly is what you want.

08Real HP: Look for HP's serial label on the bottom near the ports. A DM41X is a modern clone, and a 41CL conversion should be listed as one.

New to old calculators? The condition checklist covers battery corrosion, displays, keys and card readers, and RPN in one hour gets you typing on an HP.

Spec at a glance

Power, memory, display and keys

Modules that fit

HP-41 Math Pac

HP-41 Financial Decisions Pac

HP 82160A HP-IL Module

What to check

Which one to buy

For sale on eBay

Hewlett Packard HP 41CX Calculator With Case

Hewlett Packard HP 41CX Scientific Calculator w/Case Vintage Calc working

HP 41CX Fullnut Calculator w/ Case, Manuals, Financial & Surveying PAC ROMs

Hewlett-Packard HP 41CX Scientific Calculator w/Case - Halfnut (2834S)

HP 41CX Calculator With Case and Surveying I and Navigation Modules - Works

HP-41CX Calculator With Case Original Box Manuals New Batteries

Hewlett Packard HP 41CX Calculator Having HP Hard Leather Case and Soft Keyboard

Hewlett Packard 41CX Includes Rare Zengrange Module Memory Mudule Plus Case

Compare with

HP-41CV

HP-41C

HP-42S

Keep exploring

Spec at a glance

Power, memory, display and keys

Modules that fit

HP-41 Math Pac

HP-41 Financial Decisions Pac

HP 82160A HP-IL Module

What to check

Which one to buy

For sale on eBay

Hewlett Packard HP 41CX Calculator With Case

Hewlett Packard HP 41CX Scientific Calculator w/Case Vintage Calc working

HP 41CX Fullnut Calculator w/ Case, Manuals, Financial & Surveying PAC ROMs

Hewlett-Packard HP 41CX Scientific Calculator w/Case - Halfnut (2834S)

HP 41CX Calculator With Case and Surveying I and Navigation Modules - Works

HP-41CX Calculator With Case Original Box Manuals New Batteries

Hewlett Packard HP 41CX Calculator Having HP Hard Leather Case and Soft Keyboard

Hewlett Packard 41CX Includes Rare Zengrange Module Memory Mudule Plus Case

Compare with

HP-41CV

HP-41C

HP-42S

Keep exploring