HP 645A
Department color lasers run on department-sized cartridges, and the HP 645A family is exactly that. It feeds the Color LaserJet 5500 and 5550 series with four substantial cartridges: C9730A black, C9731A cyan, C9732A yellow and C9733A magenta.
Two whole printer series on one supply line is a gift to whoever stocks the cupboard. The 5500 and 5550 machines — base, networked, duplex and high-capacity variants alike — all take these same four cartridges, each sold separately so only the empty color is ever replaced. HP gave the family a single, generous standard size rather than a standard-and-X split, so there is no tier decision hiding inside the order either.
Toner Cartridges for HP 645A
| Cartridge | Color | Page Yield |
|---|---|---|
| C9730A | Black | See product page |
| C9731A | Cyan | See product page |
| C9732A | Yellow | See product page |
| C9733A | Magenta | See product page |
Complete sets:
The same cartridges are also stocked under the individual model names:
- HP 5500 4 Color Set (C9730A/ C9731A/ C9732A/ C9733A)
- 5500 black (C9730A)
- 5500 3 Black (C9730A)
- 5500 cyan listing carrying the C9730A code (as labeled)
- 5500dtn black listing
- 5500dtn 3 Black (C9730A)
- 5500dtn 2 Black listing carrying the C9732A code (as labeled)
- 5500dtn cyan (C9730A code, as labeled)
- 5500dtn magenta (C9733A)
- 5500dtn yellow listing carrying the C9733A code (as labeled)
- 5500n black (C9730A)
- 5500n 3 Black listing carrying the C9732A code (as labeled)
- 5500n yellow (C9732A)
- 5500hdn cyan (C9731A)
- 5550 black listing
- 5550 2 Black listing carrying the C9732A code (as labeled)
- 5550 cyan (C9730A code, as labeled)
- 5550 magenta listing carrying the C9731A code (as labeled)
- 5550 yellow (C9733A)
- 5550dn black (C9730A)
- 5550dn 3 Black (C9730A)
- 5550dn 2 Black listing carrying the C9732A code (as labeled)
- 5550dn cyan (C9730A code, as labeled)
- 5550dn magenta (C9731A code, as labeled)
- 5550dn yellow (C9733A)
- 5550dtn black listing carrying the C9731A code (as labeled)
- 5550dtn 3 Black (C9730A)
- 5550dtn 2 Black listing carrying the C9732A code (as labeled)
- 5550dtn cyan (C9730A code, as labeled)
- 5550dtn magenta (C9733A)
- 5550dtn yellow (C9732A)
- 5550n black listing (colors-only code set, as labeled)
- 5550n magenta (C9730A code, as labeled)
- 5550hdn cyan (C9731A)
- 5550hdn magenta (C9733A)
- 5550hdn yellow (C9732A)
Which cartridge should you buy?
On a department machine the arithmetic is about uptime, not unit price. Single cartridges are the right default: these printers report each color separately, and a 5500 that needs magenta gains nothing from a fresh cyan arriving in the same box. The 4 Color Set suits a planned refresh — a new department install, or a machine whose four cartridges have genuinely aged together. Because there is no extended-yield tier in this family, the only lever on change frequency is keeping a spare black ready; black is the cartridge a shared machine can least afford to wait on. Compatible cartridges here are covered by a 1-year warranty with 1-year returns.
Chip, toner and everyday use
These are big cartridges for big machines, and they reward a firm hand. Support a fresh unit from underneath as you slide it in, seat it until it stops positively, and let the printer read the chip and calibrate before judging the first page. If output thins out early, lift the cartridge out and rock it slowly end to end — with a unit this size, use both hands — to level the toner bed. Spares store best upright in their boxes; a cartridge left lying on a warm windowsill will not thank you for it.
Frequently Asked Questions
How do I make sure 645A cartridges fit my printer?
Check the code on the cartridge you are removing — C9730A through C9733A — and confirm your model in the printer list at the bottom of this page. The 5500 and 5550 family names on the machine themselves are the quickest first check.
Why are there so many listings for what looks like the same cartridge?
Because the same four cartridges are stocked under the individual model names as well — a cartridge listed for the 5550dtn is the same C9730A-series supply as the one listed for the 5500. The listings differ in name, not in what arrives; order by the code and you cannot go wrong.
Should I buy the set or single cartridges?
Singles, in most weeks: replace the one color the printer reports as empty. The 4 Color Set is for a full refresh or a new installation, and the 3 Color Set covers a refresh where the black is still healthy.
Is there a high-yield version of the 645A cartridges?
No. HP built this family in a single, substantial standard size and never added an X tier. The cartridges are large to begin with; change frequency is managed by keeping spares, not by buying a bigger cartridge.
More printers that use the same cartridges
These department models all print from the 645A shelf: COLOR LASERJET 5500, COLOR LASERJET 5500DN, COLOR LASERJET 5500DTN, COLOR LASERJET 5500HDN, COLOR LASERJET 5500N, COLOR LASERJET 5550, COLOR LASERJET 5550DN, COLOR LASERJET 5550DTN, COLOR LASERJET 5550HDN, COLOR LASERJET 5550N.