What Ink Does the Epson EcoTank ET-3950 Use?
Last Updated:Correction (October 2026): an earlier version of this guide said the ET-3950's document feeder cannot scan both sides of a page. It can. Epson lists the feeder as auto duplex scanning for letter and A4 originals. Legal-size originals scan one side only. It also named an "ET-3940" as a sibling; the 2025 models on Epson's 502 list are the ET-3930, ET-3943 and ET-3958.
Quick answer: the Epson EcoTank ET-3950 uses Epson 502 ink bottles — not cartridges. Four bottles, one per tank, and there is no XL tier, because a bottle simply fills a tank rather than being a fixed-capacity cartridge.
The wrong answer people land on is Epson 522. That family belongs to the ET-2800, ET-4800, ET-4810 and ET-2903. The bottles are keyed differently under Epson's EcoFit system, so a 522 will not fit an ET-3950 — and while you are checking, note that the two families also use different maintenance boxes. The ET-3950 takes a user-replaceable T04D100; the ET-2800-class 522 printers have no user-replaceable box at all.
CastleScore · October 2026
87/100 — Highly Recommended
Epson EcoTank ET-3950
| Pillar (weight) | Score | What it is based on |
|---|---|---|
| Owner ratings (28%) | 86 | 4.39★ average across 1,129 ratings at Staples (4.3), Best Buy (4.5) |
| Expert reviews (18%) | 80 | PCMag 4.0/5 |
| Cost per page (24%) | 99 | About 0.3¢ per page blended (black + color) with our compatible 502 bottles (7,500 black / 6,000 color pages). |
| Reliability (13%) | 89 | Most-reported problems: isolated report of poor graphics quality and a long duplex job stopping partway |
| Features (12%) | 76 | Print, copy, scan, document feeder, auto two-sided printing, Wi-Fi, Ethernet. No fax, no touchscreen. |
| Value (5%) | 87 | Running cost and owner satisfaction against a street price of about $329 |
Still sold new. Launched in July 2025 at $419.99; Best Buy and Epson list it at $329.99. Epson 502 bottles are widely sold.
CastleScore is Castle Ink’s own editorial rating, built from retailer star ratings, expert reviews, real cost per page and owner complaint patterns, checked October 8, 2026. It is not a customer review. See every ranked printer or how the score works.
The ink bottles, pictured
502 Bottles 4-packOur own compatible ink bottles, photographed in-house.
Epson EcoTank ET-3950 ink at a glance
| Position | Family | Part Number | Volume | Approx. Yield |
|---|---|---|---|---|
| Black | Epson 502 | T502120-S | 127 mL | 8,500 pages |
| Cyan | Epson 502 | T502220-S | 70 mL | 6,500 pages |
| Magenta | Epson 502 | T502320-S | 70 mL | 6,500 pages |
| Yellow | Epson 502 | T502420-S | 70 mL | 6,500 pages |
| 4-pack (BCMY) | Epson 502 | T502120-BCS | — | — |
| 3-pack (CMY) | Epson 502 | T502520-S | — | — |
Those figures come from Epson's own specification sheet for the ET-3950. You will see lower numbers quoted elsewhere — 7,500 black and 6,000 color — because those are the older published figures for the same 502 bottles, and they still circulate on retailer listings. The 8,500 and 6,500 numbers are the ones Epson publishes for this printer.
A separate figure not to confuse with either: Epson says the bottles included in the box deliver up to 6,600 black and 5,500 color. That is lower because the initial fill charges the ink delivery system. Both are Epson's numbers; they measure different things.
What it actually costs to run
Castle Ink's compatible 502 four-pack is $38.95. Against Epson's 8,500-page rating for the black bottle, that works out at roughly 0.3 cents per black page once you apportion the black bottle's share of the pack. A cartridge-based all-in-one in the same class runs 10 to 15 cents.
In plain terms: 8,500 pages of black text costs about $15 in ink here. The same 8,500 pages on an entry-level cartridge printer runs well past $850. That single comparison is the entire argument for a tank printer, and you can run it against your own volumes with the ink cost calculator.
How to refill the tanks properly
- Wait until the printer says a tank is low. Do not top up early — once ink is mixed you cannot judge the level.
- Open the tank cover and unlock the cap for the color you are filling.
- Hold the bottle upright in the port. Epson's design meters the flow and stops when full, so there is no need to squeeze.
- Fill all the way to the top line, then close the cap firmly and complete the level reset on the LCD.
Never let a tank run below its lower line — Epson warns that printing below it can damage the printer — and never mix colors between ports.
About the Epson EcoTank ET-3950
Print, scan and copy — no fax — with automatic two-sided printing, a 30-sheet ADF and a 250-sheet paper cassette. Rated at 18 ISO ppm black and 9 ppm color. Some owners find two-sided and color printing slow.
The display is a 2.4-inch color LCD, not a touchscreen. Connectivity is better than the cheaper EcoTanks: Wi-Fi 5 on both 2.4 and 5 GHz, Wi-Fi Direct, plus Ethernet and USB.
The ADF scans both sides automatically for letter and A4 originals. Legal-size and 8.5 x 13 in originals scan one side only.
The maintenance box is a T04D100, and Epson explicitly labels it user-replaceable — a real advantage over the cheaper ET-2800 class, where the waste pads are not owner-serviceable.
Its 2025 siblings on the same 502 ink are the ET-3930, ET-3943 and ET-3958. The ET-3930 has no ADF.
Common problems on this model
Faint or missing colors after the printer sits idle
The dominant EcoTank complaint, and it is dried nozzles rather than an ink problem. Epson's escalation, in order: Nozzle Check, then Print Head Cleaning, then Power Cleaning only if gaps remain — Power Cleaning uses a great deal of ink and should be a last resort. Finish with a print head alignment. Printing one color page a fortnight prevents most of it; see whether ink dries out.
Blank or very faint pages
Check the tanks visually through the window — the printer estimates levels by counting usage rather than sensing them, so the display can be wrong after a refill. Then run a nozzle check.
Will not join Wi-Fi
Print the Network Connection Report from the panel. It lists the problem it found and what to do about it, which is far more useful than generic advice. Our printer Wi-Fi setup guide covers the Epson path.
Paper feed problems
Usually roller cleaning, stack height or guide alignment. See our paper jam guide.
What ET-3950 owners ask
These are the questions that come up most for this printer on retailer Q&A pages, Epson's support pages and owner reviews, answered in our words.
Can the document feeder scan both sides of a page automatically?
Yes, for letter and A4 originals. Epson lists the feeder as auto duplex scanning. Legal-size and 8.5 x 13 in originals scan one side only.
Why did setup take so long and use so much of the ink in the box?
The first fill charges the ink system, which takes a while and uses ink. That is why Epson rates the in-box bottles at up to 6,600 black and 5,500 color pages, against 8,500 and 6,500 for replacement 502 bottles.
Can I connect it with a network cable?
Yes. Staples and Office Depot list Ethernet alongside USB and Wi-Fi, and Epson's support pages cover wired setup.
Power Cleaning didn't clear the gaps in my nozzle check. What next?
Epson says to switch the printer off for at least 12 hours, then run a nozzle check and a normal head cleaning again. If gaps remain, try Power Ink Flushing before contacting Epson support.
The screen says "Recovery mode." What happened?
A firmware update failed. Epson's fix is to connect the printer to a computer with a USB cable and run the update again.
ET-3950 quirks worth knowing
- Besides the user-replaceable T04D100 maintenance box, there is a separate ink pad for borderless printing that only an authorized Epson service provider can replace. When it fills, borderless printing stops, but regular printing and scanning still work.
- The feeder holds about 30 letter or A4 sheets but only 10 legal sheets.
- Wi-Fi is dual-band Wi-Fi 5 (2.4 and 5 GHz) with WPA3 support, and Wi-Fi Direct can run at the same time as your home network connection.
- It is a current model, not an old one: Epson launched it in July 2025 as part of its seventh-generation EcoTank line, at $419.99, rated at 18 ISO pages per minute in black and 9 in color.
FAQ
What ink does the Epson EcoTank ET-3950 use?
Epson 502 ink bottles in black, cyan, magenta and yellow.
Does the ET-3950 use Epson 522?
No. 522 fits the ET-2800, ET-4800, ET-4810 and ET-2903. The bottles are keyed differently and will not fit.
Is there an Epson 502XL?
No. There is one bottle size. Epson markets 502 as ultra-high capacity, which is branding on the base product rather than a tier above it.
Which other printers use Epson 502?
A long list, including the ET-3930, ET-3943, ET-3958, ET-2850, ET-2980, ET-3760, ET-3843, ET-3850, ET-4850, ET-4950 and ET-15000.
Does the ET-3950 fax?
No. It prints, scans and copies. In Epson's 2025 EcoTank line, the fax model is the ET-4950, which also has a touchscreen.
Can I use compatible 502 ink without voiding the warranty?
Yes. US law prevents a manufacturer voiding your warranty purely for using third-party supplies — see the legal answer.
Other printers that use Epson 502 bottles
Epson EcoTank ET-2750 · Epson EcoTank ET-2760 · Epson EcoTank ET-4750 · Epson EcoTank ET-4760 · Epson EcoTank ET-2980 · Epson EcoTank ET-4950 · Epson EcoTank ET-3843 · Epson EcoTank ET-2850
More Epson ink guides: Epson WorkForce Pro WF-4830 · Epson WorkForce WF-2950 · Epson Expression Premium XP-7100 · find any printer
Replacing it? Our highest-rated alternatives
- Epson EcoTank ET-2980 — CastleScore 90
- Epson EcoTank ET-2850 — CastleScore 86
- Epson WorkForce Pro WF-3820 — CastleScore 80
Sources
Ratings and prices were checked on October 8, 2026 and will change over time.
Need replacement Epson ink cartridges? Shop Epson ink cartridges at Castle Ink. Compatible, up to 70% less than OEM, and shipped the same day when you order by 4 PM ET.