"Toner is low" appears, the next page looks perfect, and the question is whether to order now or ignore it. The short answer: order now, keep printing. Here is what the message actually measures and how to plan around it.
How the printer knows
Most desktop laser printers do not weigh toner. HP LaserJet Pro cartridges carry a chip that tracks pages printed and pixel coverage; the printer combines that with a simple optical or magnetic sensor in some models. Canon imageCLASS cartridges use a similar page-count estimate. The result is an estimate that is good to within a few hundred pages. It is calibrated for 5% page coverage — normal business text. If you print dense graphics, "low" arrives earlier and lasts less; if you print sparse text, you get more.
The three stages on HP LaserJet
- Low (about 10–20% remaining): a yellow warning. Prints are still perfect. Order a replacement.
- Very low (about 5%): the printer's behavior depends on the Very Low setting in Administration > Supply Settings: Continue (default) keeps printing, Prompt asks each job, Stop halts. Leave it on Continue in an office; nobody wants a stopped printer at 4:55 PM.
- Empty: the printer prints until you see fading, then stops when the chip's count runs out. HP's supplies page shows "0%" but pages often still come out.
Canon imageCLASS
Canon shows "Toner low. Prepare a new cartridge" and later "Toner is running out". Under Menu > Function Settings > Printer you can set whether printing continues after the second message. The counter resets when a new genuine cartridge is detected.
How to stretch the last pages (without harming anything)
- Remove the cartridge, hold it level, rock it side to side and end to end a few times. This redistributes toner that has settled and often restores full density for 50–150 pages.
- Turn on EconoMode only for internal drafts.
- Do not tap or shake the cartridge hard, and do not blow into it; toner is a fine powder and you will make a mess or crack the seal.
What not to do
Do not try to reset the chip or cover the sensor. Modern HP firmware reads the chip on every power-up; a tampered chip is flagged and may block printing entirely. There is no safe way to make the printer believe an empty cartridge is full, and no reason to: a genuine replacement costs a few cents per page.
Plan reorders by pages, not by warnings
Look at the printer's page count monthly (HP: Reports > Usage Page; Canon: Check Counter). Divide the cartridge's rated yield by your monthly pages to get months per cartridge. A HP 58A rated 3,000 pages in an office printing 600 pages a month lasts about five months; order at month four. For a busy printer, a 2-pack keeps a spare on the shelf and costs less per cartridge.
Color printers: which color is low?
Color LaserJets and imageCLASS color models report each cartridge separately. Black runs out first in most offices; magenta and yellow last longest. Replace only the low color — see our guide on replacing one color versus a full set. A cartridge such as the HP 206A black can be replaced alone while the colors continue.
Genuine cartridges mentioned in this guide
- HP 58A Toner Cartridge
- HP 206A Toner Cartridge
- Canon 054 Toner Cartridge
- HP 58A Toner Cartridge 2-Pack
Related guides
- Toner Page Yield Explained: What ISO 19752 Means
- Toner Multipacks vs Singles: When the Pack Pays Off
Frequently asked questions
How many pages can I print after the toner low message?
Typically 5–15% of the cartridge's rated yield: roughly 150–450 pages for a 3,000-page cartridge, more if your pages are light. The printer estimates from a toner sensor or page count, not a scale, so treat it as a guide.
Will my printer stop printing when toner is low?
HP LaserJet Pro printers keep printing until toner is 'very low' and then print until quality drops, unless the administrator set 'Stop' in the Very Low settings. Canon imageCLASS printers behave the same; the stop behavior is configurable.
Should I order toner when the low warning appears?
Yes. The warning is timed so that a replacement ordered with normal shipping arrives before the cartridge is empty. Keeping one spare per printer avoids the problem entirely.
