The TN637 Question, Answered Properly

This model causes more supply confusion than any other in the family, because it straddles two series. Brother built the HL-L8570CDW as the low-total-cost variant of the platform: it ships with high-yield TN635XL cartridges in the box (5,500 pages black, 4,500 per color) rather than the standard set, and its firmware additionally accepts the TN637 — a 10,000-page cartridge in black and in each color — that the smaller HL-L8430CDW and the mid-range MFC models cannot use.

One store-reality note before the table: we do not yet carry a compatible TN637, so the TN637 row below carries yield information only, with no price and no link. Everything we can actually sell you for this printer is in the TN635 rows and the color-by-color list.

Yields and Cost per Page

Cartridge	Yield	Our compatible price*	Cost per page
TN635BK (black)	~3,000 pages	$50.80	≈1.7¢
TN635C / M (each)	~1,800 pages	$50.80	≈2.8¢
TN635Y	~1,800 pages	$47.34	≈2.6¢
TN635XLBK (black)	~5,500 pages	$53.30	≈1.0¢
TN635XLC / M (each)	~4,500 pages	$53.30	≈1.2¢
TN635XLY	~4,500 pages	$46.48	≈1.0¢
TN635XXLBK (black)	~7,500 pages	$76.47	≈1.0¢
TN635XXLC / M / Y (each)	~6,500 pages	$76.47	≈1.2¢
TN637 (each color incl. black)	~10,000 pages	genuine only — see note	—

*Prices checked on our product pages on November 2, 2026; they can change. Yields are Brother's ratings.

Study the last three data rows and a pattern emerges: from the XL upward, cost per page barely moves at our prices — around a cent for black whichever of XL, XXL you pick. What changes is the service interval. On a Workhorse printer managed by an IT team, the XXL's 7,500-page black means fewer tickets, fewer interruptions, fewer cartridges in the waste stream. If you manage this machine yourself, the XL is the same money per page with a smaller bill each time.

Every Cartridge We Sell for It, Color by Color

• Black: TN635BK · TN635XLBK · TN635XXLBK
• Cyan: TN635C · TN635XLC · TN635XXLC
• Magenta: TN635M · TN635XLM · TN635XXLM
• Yellow: TN635Y · TN635XLY · TN635XXLY

Replacing a Cartridge

With the printer on, open the front cover and pull the drum assembly toward you. Press the green lock lever above the color the display names, lift the old cartridge out, and give the new one a gentle side-to-side rock before stripping its cover. Push it into the slot until the lever clicks, slide the assembly back, and close up. The supply screen will register the new cartridge immediately.

Why the Workhorse Label Matters Beyond Toner

Brother aims this model at managed fleets: mass-deployment tools distribute settings, security policies and firmware across many devices at once, and Triple Layer Security with an integrated NFC card reader handles badge release at the device. Print speed matches the rest of the family at up to 33 pages per minute, paper starts at 250 sheets plus a 50-sheet multipurpose tray and can reach 1,340, and dual-band Wi-Fi joins Gigabit Ethernet. For supply planning, the fleet tools are the sleeper feature — low-toner alerts across a fleet turn cartridge ordering into a schedule instead of a series of emergencies, whichever tier you standardize on.

Sets and Spares

Restocking can go either of two ways on this model. A TN635XL four-color set is priced at $158.14 — a full $48.24 under the $206.38 the four XL singles add up to — with parallel sets offered in standard and XXL sizes, so a full-row refresh arrives as one box. Or keep the pattern lean: a standing spare of the black in whichever tier you standardized on, with colors ordered as their gauges drop. On the TN637 question, the honest position is simple: the printer can use it, Brother sells it as a genuine cartridge, and until a compatible version reaches our shelf we would rather tell you that than steer you to a substitute.

Drum, Belt and Waste Box

The DR635CL drum (about 30,000 pages) serves every cartridge this printer accepts, TN637 included — switching series never means switching drums. The BU635CL belt unit and WT229CL waste toner box are each rated around 50,000 pages. None of the three has a compatible listing in our store at present, so they appear here unlinked; each is a genuine-part purchase when its counter runs down, with warnings displayed long beforehand.

Frequently Asked Questions

My printer came with XL cartridges — must replacements be XL too? No. The in-box set is high yield, but the printer accepts standard, XL and XXL TN635 cartridges interchangeably, plus the TN637.

Is the TN637 worth hunting down as a genuine cartridge? It is the only way past 7,500 pages in black and the only 10,000-page color option. For a heavily used machine where every swap is a service visit, that can justify genuine pricing; for a printer you walk past daily, our XXL compatibles do the same job per page for less.

Can I share cartridges between this and our HL-L8430CDW? All TN635 tiers, yes — the two models share them completely. Just do not send a TN637 back the other way; the L8430CDW cannot use it.

Does the drum change when I switch from TN635 to TN637? No. Both series run on the same DR635CL drum unit.

What print volume suits this model? Brother positions it for busy work teams; at 33 ppm with a 1,340-sheet ceiling it is built for shared departmental duty, and its supply tiers assume thousands of pages a month rather than hundreds.

Other Printers That Use TN635

The rest of the family — HL-L8430CDW, HL-L8430CDWT, MFC-L8730CDW, MFC-L8930CDW, MFC-L8970CDW and MFC-EX575 — takes every TN635 cartridge linked above. The TN637 splits the family three-and-three: this printer, the MFC-L8970CDW and the MFC-EX575 accept it; the other three do not.

Everything we stock for this model is collected on our HL-L8570CDW toner page.