HP 45 Ink Cartridges
The HP 45 black ink cartridge series (51645AA) supplies legacy Deskjet, Officejet, and Photosmart models with high-density pigment ink. Both genuine HP cartridges and high-performance compatible alternatives are available to support heavy mono document production. Our 4.8 Google Star rating shows that our customers consistently receive high-quality cartridges backed by reliable performance.
Printers Compatible with HP 45 Ink Cartridges
Expected page output and replacement cycles
Page yields for HP 45 cartridges are calculated based on the ISO/IEC 24711 standard for monochrome inkjet printing, which assumes 5% coverage on standard A4 paper. Heavy text documents or graphics will reduce total page output.
| Cartridge Number | Type | Colour | Page Yield | Cost Per Page |
|---|---|---|---|---|
| 45 | Standard | Black | 883 | $0.15 |
Cost Per Page = Total Cartridge Price ÷ Page Yield (at 5% coverage). Prices based on Genuine cartridges.
Choosing between genuine and compatible options
Opting for compatible HP 45 cartridges drops your cost per page from 15 cents to under 7 cents while maintaining identical 42ml ink capacity and printhead nozzle architecture. Under Australian Consumer Law, using compatible cartridges does not void your printer warranty. For a detailed comparison between OEM and third-party options, read our guide on genuine vs compatible cartridges.
How most users manage replacements
If you print large volumes of monochrome text documents or architectural drafts, compatible HP 45 cartridges deliver substantial cost savings per page. Compatible options include a full money-back guarantee if they fail to perform. Review our returns policy for full details on guarantee claims. Free delivery applies on all orders over $99, dispatched quickly from our warehouses in Perth, Brisbane, Sydney, Melbourne, and Adelaide. Browse our full range of HP ink cartridges for all supported models.
Pro Tip
HP 45 cartridges feature an integrated thermal printhead built directly onto the cartridge base. If your printer has been idle for several months and output appears streaked, perform a manual wipe of the copper contacts and nozzle plate using a lint-free cloth dampened with distilled water rather than running multiple automated cleaning cycles, which consume valuable ink.
Frequently Asked Questions
Why does the HP 45 cartridge cost more than many modern ink cartridges?
The HP 45 uses an integrated printhead design containing both the ink reservoir and the micro-nozzle firing mechanism. Unlike modern printers where the printhead stays inside the printer, replacing an HP 45 cartridge installs an entirely new firing system, which increases the manufacturing cost of genuine units.
Will my older Deskjet or Officejet printer recognise a compatible HP 45 cartridge?
Yes. HP 45 cartridges do not use modern microchip tracking system restrictions found on contemporary printers. Compatible HP 45 units use identical electrical contact plates, allowing legacy printers to accept them without firmware blockages or false error messages.
Does the HP 45 black ink dry out if left unused for long periods?
Because pigment-based ink is prone to settling, long periods of inactivity can cause dried residue around the exterior nozzles. Keeping the printer powered on allows automatic maintenance sweeps, or you can manually clean the printhead faceplate with warm distilled water to clear dried ink.
