Brother lists the TN770 for six printers, the TN730 and TN760 for 16

Will a TN770 fit an HL-L2350DW? Brother does not list it for that printer. The HL-L2350DW is missing from the TN770's product page and from the TN-770 row in its user guide. Brother's support page for the HL-L2350DW shows two toner cartridges and no other: the TN730, rated at about 1,200 pages, and the TN760, rated at about 3,000 pages. The TN760 is the highest-yield cartridge Brother lists for it.

Across the range, Brother lists the TN770, rated at about 4,500 pages, for six printers: the HL-L2370DW, HL-L2370DWXL, HL-L2379DW, MFC-L2750DW, MFC-L2750DWXL and MFC-L2759DW. It lists the TN730 and TN760 for all sixteen printers in the table below, those six included. Brother does not say why the other ten are left off the TN770 list. If your model is not on it, your choice is between the TN730 and the TN760.

Brother's US product pages for the cartridges name fewer printers. The "Use with" lines on those pages name twelve printers for the TN730 and TN760, and four for the TN770. They leave out four printers that the user guides include: the HL-L2325DW, HL-L2379DW, MFC-L2690DWXL and MFC-L2759DW. Brother's US support pages list the TN730 and TN760 for the HL-L2325DW, and all three cartridges for the HL-L2379DW and MFC-L2759DW. For the MFC-L2690DWXL, the user guide lists the TN730 and TN760 and not the TN770. If you own one of these four printers, go by the support page or the user guide, not the cartridge's product page.

Brother writes these names more than one way. Its cartridge pages say "HL-L2370DW XL", its printer pages say "HL-L2370DWXL", and its support site says "HL-L2370DW(XL)". It also uses both TN730 and TN-730 for the same part.

The first cartridge is not the same across the range. Brother says the one that ships with a printer may be a starter, a standard or a high-yield cartridge, depending on the model and the country where it was bought. For these models, Brother's figures are below.

On the ten printers that came with only a 700-page starter, any of the replacements is rated for more pages than the cartridge you started with, even the 1,200-page TN730. Brother's help article on toner yield for the DCP-L2550DW and MFC-L2750DW says the starter holds less toner than the standard and high-yield replacements.

Three printers are different. The MFC-L2717DW came with a cartridge rated at about 1,200 pages, the same as a TN730, so only the TN760 is rated for more. The HL-L2379DW and MFC-L2759DW came with a cartridge rated at about 4,500 pages. Of the replacements, only the TN770 is rated that high.

On the XL printers, XL is part of the printer's name. It is not a cartridge size. The HL-L2370DWXL and MFC-L2750DWXL each came with a TN-760 and a TN-770, rated at about 7,500 pages between them. The MFC-L2690DWXL came with a starter and a high-yield replacement, about 3,700 pages between them.

To see what yours came with, look under Carton Contents in the In the Box section of your model's page on Brother's US site. The notes under the Supplies table in your model's user guide give the same figures.

Each step up is smaller than the one before. The TN760's 3,000 pages against the TN730's 1,200 works out to 2.5 times. The TN770's 4,500 against the TN760's 3,000 works out to 1.5 times. The TN770 against the TN730 works out to 3.75 times.

All three figures come from the same test, ISO/IEC 19752, the international method for measuring the page yield of toner cartridges in monochrome laser printers and all-in-ones. Brother's 2018 description of the test says it uses at least three printers and nine cartridges, printing a standard test page continuously at about 73 °F (23 °C) and 50% humidity. For Brother's cartridges, each runs until the printer shows Replace Toner. Brother then states a figure no higher than the low end of a 90% confidence range from those runs.

Your own count may differ. Brother names paper size, pages per job, how much is printed on each page, font size, and graphics or charts as things that change how many pages a cartridge gives. Its help article for the DCP-L2550DW and MFC-L2750DW takes a typical page to be one letter sheet with 4% to 5% coverage. Brother also says the standard helps buyers compare page yields between makers, and all three cartridges are rated under it. So the figures are fit for comparing one cartridge with another. For cost, divide your own prices by these page counts, as on the cost-per-page page.

• One digit apart. The HL-L2350DW and HL-L2370DW differ by one digit. So do the MFC-L2730DW and MFC-L2750DW. Only the second model in each pair is on Brother's TN770 list.
• Listing titles. A listing that strings TN730, TN760 and TN770 together in its title does not show that all three fit your printer. Brother's own lists do: the Consumables & Accessories page for your model, or the Supplies table in its user guide.
• Non-Brother cartridges. Brother notes that cartridges sold as "compatible" or "for use with" Brother printers may not be rated under ISO/IEC 19752. Their page counts may not line up with the figures here.
• The drum is a separate part. The toner cartridge locks into a drum unit, and the two come out of the printer together when you change toner. The HL-L2350DW, for example, ships with a DR730 drum unit rated at about 12,000 pages. A Replace Drum message is a different problem; see what to do when a Brother asks for a new drum.
• Timing. Toner Low is a warning, not a stop. Brother says to keep printing while the print quality holds and to have the new cartridge ready. Leave it in its packaging until you install it. Brother's guide says toner life shortens if a cartridge sits unpacked for a long time.

Match the model name character for character, reading it off the printer rather than an old order. Brother's guide to finding a model name uses other models as its examples. It shows the name printed on the machine's upper face, often on or beside the control panel or display.

Then open your model's page on Brother's support site and choose the Consumables & Accessories tab. It lists the toner cartridges Brother names for that model, each with its page count. The Supplies page under Appendix in your model's Online User's Guide gives the same cartridges and the models each one applies to.

Use the support site for the country where you bought the printer. TN730, TN760 and TN770 are the numbers Brother uses in the US and Canada. The same model name sold elsewhere can take a differently numbered cartridge. Brother's UK support site lists the TN-2410 and TN-2420 for the HL-L2350DW, and its Australian site lists the TN-2430 and TN-2450. The user guide's Supplies page notes that order numbers vary by country and region.

On the six TN770 printers, you are choosing among three cartridges. On the other ten, you are choosing between two, and the TN760 is the larger. The general method for any brand is on confirming the right cartridge for the printer you already have.