How to Find Your Printer Model Number
Your printer's model number is almost always printed on a sticker on the printer itself — check the front panel, the top edge above the paper tray, or inside the door where cartridges load. If you can't find a sticker, your printer's on-screen menu or a one-time test-page print will show it too.
Why the exact model number matters
Printer families that look nearly identical from the outside — an HP OfficeJet 4650 versus a 4652, or a DeskJet 2620 versus a 2622 — can use completely different ink cartridges. Manufacturers frequently reuse a body design across several model numbers while quietly changing the cartridge compatibility, or vice versa: near-identical model numbers sometimes use different families entirely. That's why every lookup on this site is keyed to the full, exact model number rather than the general product line name. Guessing from the product line ("it's an OfficeJet, so it probably takes the same ink as my last OfficeJet") is the single most common cause of ordering the wrong cartridge.
Where to look, in order of likelihood
1. The front or top panel. Most HP inkjet printers have the model name printed directly on the plastic housing, often near the control panel or above the output tray. Look for a name like "OfficeJet 4650" or "DeskJet 2734" printed in a clean sans-serif font — this is usually the marketing name, and it's often (but not always) enough to identify the cartridge family.
2. Inside the cartridge access door. Open the door where the ink or toner cartridges load. Many models have a smaller label inside this door with the full model number and sometimes the exact cartridge part numbers already printed on it — if you find cartridge numbers here directly, you can skip the lookup entirely and search that part number at your preferred retailer.
3. The bottom or back of the unit. Look for a rectangular regulatory or serial-number label, usually white or silver, on the underside or rear of the printer. This label typically includes a "Model" or "Product Number" field. For HP printers this is sometimes formatted as a product number (like a code beginning with a letter followed by numbers) rather than the friendly marketing name — if that's all you can find, search that code directly rather than guessing at the marketing name.
4. The printer's on-screen display or control panel menu. If your printer has a screen, check Settings (or the gear icon) → About, or Setup → Printer Information. Most HP printers list the exact model name here without needing to physically inspect the unit — useful if the printer is already set up somewhere hard to reach.
5. A printed information or configuration page. Nearly every printer can print a self-test or configuration page directly from its control panel, usually via a Setup or Reports menu (sometimes a hardware button combination on very simple models — check the printer's included quick-start card if the menu isn't obvious). This page typically lists the model number along with firmware version and network details.
6. Your computer's printer settings. If the printer is already installed and set up on a Windows or Mac computer, open the system's printer settings (Windows: Settings → Bluetooth & devices → Printers & scanners; Mac: System Settings → Printers & Scanners) and click into the printer's properties. The full model name is usually shown there, and it's the same name Windows or macOS used when it originally installed the printer driver.
7. The original box or receipt. If you still have the packaging or a purchase receipt/order confirmation email, the model number is printed on both — this is often the fastest option if the printer itself is buried under paper or awkward to move.
What to do once you have the model number
Type the full model number — brand plus number, like "HP OfficeJet 4650" rather than just "4650" — into the search box at the top of any page on this site. That takes you straight to the model page listing the exact standard and XL cartridge part numbers for that printer, with direct shopping links. If your printer isn't listed yet, double-check you have the complete model number rather than an abbreviated version; a surprising number of near-duplicate model numbers (like the 2620/2622 example above) exist specifically because manufacturers update internal components — including cartridge compatibility — without renaming the product line.
A note on "series" versus exact model
Manufacturers organize printers into series or families (like "OfficeJet 4650 series"), and it's genuinely true that most printers within a tight numeric range in the same series use the same cartridges. But "most" isn't "all," and the exceptions are exactly the ones worth avoiding — see our genuine vs. compatible ink guide for related buying tradeoffs once you've confirmed compatibility. When in doubt, look up your exact number rather than relying on "close enough."