Printer says ink low but the cartridge is not empty what the gauge is actually measuring, and how to keep printing on the ink you already paid for

A low-ink warning is not a measurement. On most consumer printers nothing looks inside the cartridge at all: the machine counts what it thinks you printed and subtracts from a number the chip handed it on day one. That estimate drifts, and it drifts hardest for the people who print least like the test document the estimate was built on. So the gauge can read empty while the cartridge still sloshes. This guide covers what the reading is based on, what lab weighing found was still inside cartridges the printer had declared dead, and the override path on each brand when you need the job finished tonight.

The short version: Do the cheap check before you buy anything. Pull the cartridge and weigh it in your hand against a new one of the same number, or hold it to a bright light if the plastic is translucent. On a tank printer just look at the tank window. If it feels or looks close to full, the gauge is estimating badly and the override paths below apply. If it feels light and the print is already streaking, the warning is honest and a new cartridge is the answer.

The gauge is a running estimate, not a dipstick

Two different mechanisms sit behind that little bar on the screen, and they fail in different ways.

Chip and page counting. The cartridge chip declares a starting capacity, and the printer subtracts as it works, weighting for how many pages, what quality setting, and how much of the page it thinks was covered. Nothing is being sensed. A page of dense photo covers far more than a page of text, and where the printer's assumption about your mix is wrong, so is the bar.
Optical sensing. Some designs shine light through the ink chamber and read what comes out the other side, which is closer to a real measurement. It has its own failure mode: ink film sprayed on the inside of the window reads as ink that is still there, or a bubble reads as empty.

HP puts it plainly in its own support note: ink level warnings and indicators are estimates provided for planning purposes, and when the alert appears you can carry on printing until the quality is unacceptable or until a replace message appears. Epson makes the matching admission from the other end, telling owners that a small amount of ink deliberately stays behind after the replace indicator lights, so the head keeps a clean supply.

So the number on screen is a forecast with a safety margin built in, and both the forecast and the margin were tuned around the maker's own cartridge rather than yours.

How much is usually still in there

The most useful evidence here is old but it was done with a scale rather than a press release. The PC World Test Center weighed black cartridges full, weighed them again at the moment the printer refused to continue, then emptied them completely and weighed them a third time. The gap between the second and third weighings is ink you paid for and could not use.

A Canon multifunction stopped printing with about 24 percent of the black ink still in the tank when running Canon's own cartridge.
The same printer with an aftermarket cartridge fitted stopped with nearly 45 percent left, because the printer was counting against the yield of the OEM tank while the aftermarket tank held more ink than that.
Across the Canon, Epson and Kodak machines tested, cartridges were reported empty with as much as 40 percent of their black ink remaining. The narrowest result was around 8 percent in an Epson cartridge in an Epson printer.
The HP tested that round never forced a swap at all. It warned, then kept going.

Two things follow from that spread. Aftermarket cartridges with extra ink in them lose proportionally more to the counter, since the counter has no idea the tank is bigger, which is worth knowing before you pay extra for a high fill. And the brand you own matters more than any trick: a printer that hard stops will hard stop, and a printer that only nags will let you drain the thing.

You will also see a widely quoted figure that most of the ink in a cartridge is thrown away, traced back to a TUV Rheinland study on inkjet efficiency. Worth knowing who paid for it: Epson commissioned that work, and Epson sells the tank printers that the finding flatters. Treat it as a claim with an interest attached, and lean on the weighed results instead.

Keep printing tonight: the override on each brand

Every maker has a documented way to carry on past the warning, because every maker gets asked. The paths differ more than people expect.

HP inkjet. Select OK on the panel, in the HP app, or on the computer, and the job continues. HP's guidance is to print on until quality drops or a replace prompt arrives. Some models switch to a backup mode as a supply runs out, where blacks come out weaker or the page prints in greyscale. HP also notes that its alerts are calibrated for genuine HP cartridges and may simply be wrong on a refilled or remanufactured one.
HP laser. The behaviour at very low is a setting, not a fixed rule. On the panel go to Setup, then System Setup, then Supply Settings, pick the black or colour cartridge, and open Very Low Setting. Continue prints straight through the warning, Prompt stops and asks (the default reminder interval is 100 pages), and Print Black keeps you going in black when a colour supply is the one complaining. One consequence to know: HP treats reaching very low as the end of that cartridge's Premium Protection warranty.
Canon. With the cartridge installed, hold the Stop, Stop/Reset or Resume/Cancel button for at least five seconds and release. Canon's own answer to this question puts the hold at seven seconds or more, and it has to be repeated for each cartridge that is complaining. This switches off remaining-ink-level detection for that tank, so the gauge stops reporting rather than starts reading correctly. Fitting a genuine Canon cartridge turns detection back on.
Epson cartridge models. Low is only a heads-up and you keep printing. Expended is a wall: Epson's documentation states you cannot continue with one cartridge expended even when the others are full, so that colour has to be replaced before anything prints. Epson also stops showing cartridge status entirely when non-genuine ink is fitted, which is why a working third-party cartridge often shows no level at all.
Brother laser. Enable Continue Mode. On menu models: Menu, General Setup, Replace Toner, Continue, Stop/Exit. On LED models with no display, make sure only the Ready light is on and press Go seven times, and all the LEDs blink twice to confirm. The machine then prints past Replace Toner until it hits Toner Ended, which is a genuine hard stop at the cartridge's maximum operational life. Fitting a new toner turns the mode off again by itself. If you receive faxes, Brother asks after each one whether the print quality was acceptable, and holds the fax in memory if you say no.

Turning the override on is the simple part. Print one page you care about and look at it closely before you commit a long job to a cartridge the printer has already written off.

After a refill, a chip reset, or a compatible cartridge

This is where most of the wrong readings come from, and it is not really a fault. The counter tracks the chip, so a cartridge that has been topped up without the chip being touched still reports the state it was in when you took it out: empty.

A refill without a chip reset reads empty, correctly, from the printer's point of view. The ink is new, the chip's memory is not. Either reset the chip with a resetter for that cartridge family or take the override route and print with detection off.
Detection off means the gauge is gone, not fixed. On Canon the level shows as unknown afterwards, and you are back to judging by eye. Some people prefer that to a bar that was lying anyway.
A blank or question-mark level on a compatible cartridge is often normal. Epson hides cartridge status for non-genuine ink by design, so no reading does not mean no ink.
Check the contacts before blaming the chip. A film of ink or a fingerprint on the gold pad produces intermittent low and not-recognised errors that look identical to a dead chip. Wipe the pad with a dry lint-free cloth, reseat until it clicks, and try again.
Refillable tanks are their own case. Canon G series and similar count ink rather than sensing it, so the counter needs resetting from the maintenance menu after you top up the bottles or the machine keeps insisting it is out.

If the error is a flat refusal to recognise the cartridge rather than a level complaint, that is a different problem with a different fix. Our guides on HP cartridges that are not recognised and resetting a Canon after an ink error cover it, and the firmware DRM tracker covers the models where a firmware update is the real cause.

When low really does mean low

Overriding a warning that was wrong costs you nothing. Overriding one that was right can cost you a printhead, so it is worth knowing which you are looking at.

Judge by the printed page rather than the bar on screen. Fading that gets worse down the sheet, a colour cast that will not correct, missing horizontal bands, or a nozzle check with gaps in one colour all mean that supply is genuinely running dry.
Running an inkjet head dry is the real risk. The ink cools the nozzles as it fires. Print hard on an empty tank and you can burn nozzles that no cartridge will bring back. Canon is explicit that continued printing in the ink-out condition is at your own risk and that the tank should be replaced immediately afterwards.
Laser has more slack. Toner does not damage anything by running out. Take the cartridge out and rock it gently end to end to redistribute what is left, refit it, and you will usually get a further run of pages before the print goes patchy.
One dry colour still ruins black text. Composite blacks pull from the colour tanks on many inkjets, so a starved cyan shows up as a muddy or banded black page. Printing greyscale, or black only where the driver offers it, sidesteps that.
Some stops are final. Epson expended and Brother Toner Ended are not warnings you can talk your way past. At that point the cartridge is finished as far as the machine is concerned.

Getting fewer wrong warnings in the first place

You cannot make the estimate accurate, but you can stop it dictating your buying.

Keep one spare of the colour that runs out first, and stop treating the first warning as a purchase trigger. On most machines that alert arrives with a real run of pages still in the tank.
Turn the nagging down rather than off. HP's low-ink notifications can be disabled in the printer software or the HP Smart app, and on HP lasers the Very Low behaviour is the setting described above. A quieter printer makes it easier to notice the one warning that matters.
Judge cartridges by cost per page rather than sticker price. A cheap cartridge that the counter cuts off early is not cheap, and our cost-per-page ranking shows how far apart models sit on this.
If wasted ink is what is annoying you, the structural fix is a refillable tank machine, where you can see the level through the window and top it up from a bottle. Our ink tank versus cartridge comparison works through whether the hardware premium pays back for your volume.
Print something every week or two. Cartridges left to sit clog, and a clogged nozzle produces faded output that looks exactly like low ink and gets a perfectly good cartridge thrown away. Our guide to preventing clogs has the routine.

Common questions

Why does my printer say ink is low when the cartridge is still heavy?

Because on most consumer printers nothing measures the ink. The cartridge chip reports a starting capacity and the printer subtracts an estimate based on pages printed, quality setting and assumed coverage. If your printing is lighter than the model assumes, the counter reaches zero while ink remains. HP states outright that its ink level indicators are estimates for planning purposes.

How much ink is actually left when a printer says empty?

Enough to matter. PC World weighed cartridges at the point printers refused to continue and found a Canon machine stopping with about 24 percent of its black ink left on an OEM cartridge and nearly 45 percent on an aftermarket one. Across the printers tested, some reported empty with as much as 40 percent remaining, while the narrowest case was around 8 percent.

How do I make a Canon printer keep printing when it says the ink has run out?

With the cartridge in place, press and hold the Stop, Stop/Reset or Resume/Cancel button for at least five seconds and release. Canon's own support answer suggests holding for seven seconds or more, and you repeat it for each cartridge that is flagged. This disables remaining ink level detection for that tank, so you lose the level reading and judge by print quality instead. Fitting a genuine Canon cartridge switches detection back on.

Can I keep printing on an Epson when one cartridge reads empty?

Not on a cartridge model. Epson distinguishes low from expended: at low you carry on, but once a cartridge is expended the printer will not print even if every other colour is full, so that one has to be replaced. Epson also hides cartridge status when non-genuine ink is installed, so a blank level on a working third-party cartridge is expected rather than a fault.

Is it safe to keep printing after the low ink warning?

On a laser, yes. Toner running out damages nothing, and rocking the cartridge end to end usually buys more pages. On an inkjet, be more careful: the ink cools the nozzles as they fire, and printing hard on a genuinely dry tank can burn out nozzles permanently. Canon states that printing in the ink-out condition is at your own risk. Watch the page, and stop when output starts fading or banding.

I refilled the cartridge and it still says empty. What now?

The chip is reporting its own memory, not the new ink, so the reading is consistent from the printer's side. Either reset the chip with a resetter made for that cartridge family, or use the brand override to disable level detection and print without a gauge. On refillable tank machines such as the Canon G series, reset the ink counter from the maintenance menu after topping up the bottles.

Keep reading

Reset a Canon printer after an ink error the support codes behind ink out, and the full reset sequence.
Reset an Epson printer and clear an ink error what to do when Epson goes from low to expended.
Reset a Brother toner counter the counter reset that a refilled or new Brother toner needs.
Why is my printer printing blank pages? when it is a clog or a seal rather than an empty cartridge.
Do ink and toner cartridges expire? whether that spare in the drawer is still worth fitting.
What to do with empty cartridges what to do with it once it really is empty.
What the cartridge chip actually does why the level is a counter on a chip rather than a measurement.
It will not print black and only a colour is empty when the gauge stops being a warning and starts being a block.
Setup cartridges and what the first refill costs an in-box cartridge reporting empty early is usually documented behaviour.
Waste ink pads and maintenance boxes another estimated counter presented to you as a measurement.
Is the XL cartridge actually cheaper? what the gauge is measuring in a cartridge you paid extra to fill.

Sources

HP Support, HP inkjet printers, Ink Alert or Low on Ink message, stating that level warnings are estimates and that printing can continue. support.hp.com
HP Support, HP Color LaserJet Pro printers, A Cartridge is low message, on changing very low behaviour in Supply Settings. support.hp.com
Canon Support, Press and hold Stop/Reset button for at least five seconds, the official ink-out override and its warning. support.usa.canon.com
Canon Community, moderator answer on refilled cartridges, the seven second hold and per-cartridge repetition. community.usa.canon.com
Epson Support, Precautions on ink cartridge replacement, on expended cartridges blocking printing and status being hidden for non-genuine ink. files.support.epson.com
Brother Support, Toner continue mode, the menu path, the Go button sequence, and the Toner Ended hard stop. help.brother-usa.com
PC World Test Center via Macworld, How much ink is left in that dead cartridge, the weighed results for OEM and aftermarket cartridges. www.macworld.com
Ars Technica on the TUV Rheinland inkjet efficiency study, noting that Epson commissioned it. arstechnica.com

Last updated 13 September 2026. This guide is general information, not a repair warranty. Printer menus and HP's model lists change, so confirm the exact steps for your model on the manufacturer's support site before you make changes.