Buying a used Prusa printer: models, upgrade kits and what to check

A used Prusa is worth at most its successor’s new price minus the kit that converts it. Pay more and the used printer plus the kit costs more than the current model new. Prusa sells no used or refurbished printers itself; its used goods category lists only parts.

Prices are Prusa’s US store listings on 2 November 2026. The last column is our arithmetic on them: the new price minus the kit.

Used printer	Current model, new	Official kit	Used price at which printer + kit = new
i3 MK3, MK3S or MK3S+	MK4S: $999, kit $709	MK3/S/+ to MK4S, $629	$370 (assembled), $80 (kit)
MK4	MK4S: $999, kit $709	MK4 to MK4S, $109.99	$889 (assembled), $599 (kit)
CORE One	CORE One+ (Gen 2): $1,299, kit $999	CORE One to CORE One+, $9.99, then CORE One+ to Gen 2, $54.99	$1,234 (assembled), $934 (kit)
CORE One+	CORE One+ (Gen 2): $1,299, kit $999	CORE One+ to Gen 2, $54.99	$1,244 (assembled), $944 (kit)
CORE One L	CORE One L+: $1,999, assembled only	CORE One L to L+, $24.99	$1,974
XL, one toolhead	XL+ Single-Tool: $2,299	XL to XL+ (1 tool head), $279.99	$2,019
MINI	MINI+: $549, sold only as the semi-assembled “Enclosure Bundle”	MINI to MINI+, $28.99, out of stock	No kit in stock

You assemble every upgrade kit yourself, so the new model’s kit price is the like-for-like comparison. Prusa calls the MK3-to-MK4S kit “the full upgrade” but does not say the CORE One, CORE One L or XL kits match a new printer. The Prusa 3D printer prices list has every model.

What should you check on a used Prusa printer?

Check five things specific to Prusa: the model and revision, on the serial label and in the firmware; the print-time statistic; whether it was built from a kit; the original invoice, which decides any warranty left; and the parts that make it complete, such as the print sheet, filament sensor, multi-material unit and, on an MK3, the power supply.

The used 3D printer inspection checklist covers the frame, motion system, hotend and test print on any brand.

Which model and revision is it?

Prusa’s silver serial label sits above the power supply or on the rear plate of an MK-series printer, on the right of the Z-axis extrusion of a MINI or MINI+, between the power supply and xBuddy board of a CORE One, and at the rear of an XL. Numbers start with CZPX before November 2021 and SN after. The MK4 family and the CORE One also show it under Info > Version Info.

The kits reuse the frame, so check the hardware and firmware too:

• MK3S (February 2019): a reworked extruder and an optical filament sensor triggered by a mechanical lever.
• MK3S+ (November 2020): a SuperPINDA bed-leveling probe, metal clips instead of U-bolts on the Y-axis rods, and a reinforced X-end.
• MK4, MK4S, MK3.9 and MK3.9S: Settings > Hardware > Printer Type shows which of the four the firmware is set to.

How many hours has it printed?

On an MK3, MK3S or MK3S+, open LCD Menu > Statistics with the printer idle; a factory reset clears it. On the MINI and MINI+ (firmware 4.4.0 or later), MK4, MK4S, MK3.9S, CORE One, CORE One L and XL, go to Info > Print Statistics > Statistics > Print Time. A MINI has stored print time only since firmware 4.3.3. Print hours on a used printer explains how to read the total.

Was it a kit, and is any warranty left?

Ask for the original invoice. It shows whether the printer was bought as a kit, and Prusa’s warranty covers a kit part by part, with damage from improper assembly excluded. Outside the EU, Liechtenstein, Switzerland, Norway and Iceland, the warranty runs one year from first delivery, not from the resale. On 2 November 2026, only a printer first delivered after 2 November 2025 can have any left. Prusa also tells buyers from a private seller to open an account in its e-shop. 3D printer kit prices compares Prusa’s kit and assembled prices.

Is anything missing?

• Print sheet: a Smooth PEI Print Sheet costs $32.99 and fits every MK2.5 to MK4S and the CORE One and CORE One+ (Gen 2). The MINI sheet costs $22.99.
• Filament sensor: a $20 option when the MINI+ launched, now in the box.
• Multi-material unit: the MK3S+ record lists the MMU2S; the MK4, MK4S and CORE One list the MMU3. Prusa sells the MMU3 for the MK4S and MK3.9S at $389 assembled, and says an MK3 needs the $53.99 MK3S+ kit before it takes one.
• Power supply (PSU) on an MK3: a black PSU works with every upgrade kit. A silver one needs a harness or adapter, and must be swapped for a black one before the CORE One conversion.

Can a used Prusa MK3S be upgraded to an MK4S?

Yes. Prusa’s Original Prusa i3 MK3/S/+ to MK4S upgrade kit costs $629 on its US store as of 2 November 2026 and fits the MK3, MK3S and MK3S+. It replaces the electronics, screen, extruder, motors and belts. It keeps the frame, power supply and heatbed, so it needs a black PSU or an adapter and a screwed heatbed cable.

Check the heatbed before you buy: a bed with a screwed power cable (Prusa’s “2+3 screws”) stays, and one with a soldered cable (“2+1”) must be replaced. Prusa’s i3, MK4 and MK4S kits on 2 November 2026:

Kit	US price	What changes
MK3/S to MK3S+	$53.99	SuperPINDA, Y-axis bearing clips, IR filament sensor; you print the plastic parts
MK3S/+ to MK3.5S	$269.99	xBuddy board, xLCD screen, Input Shaper, Wi-Fi, NFC and Ethernet; keeps the extruder, hotend and motors
MK3/S/+ to MK3.9S	$539	The MK4S kit without the 0.9° X/Y motors
MK3/S/+ to MK4S	$629	xBuddy, xLCD, Nextruder with load cell, X/Y/Z motors, belts, Z rods, 360° fan, CHT nozzle
MK3.9 to MK3.9S	$109.99	360° cooling and a high-flow nozzle
MK4 to MK4S	$109.99	360° fan and shroud, CHT nozzle, Wi-Fi board and NFC antenna
MK4S to CORE One+ (Gen 2)	$719	Converts an MK4S into the enclosed CoreXY CORE One+ (Gen 2), reusing its sheets, hotend and nozzles

Only the MK4S converts directly to a CORE One, per Prusa’s help center. An MK4 or MK3S+ becomes an MK4S first, an MK3.9S needs 400-step X/Y motors, and the MK3.5 and MK3.5S have no path. Taking an MK3S+ all the way costs $1,348 in kits ($629 plus $719), against $1,299 for a new assembled CORE One+ (Gen 2) or $999 as a kit.

The MK2 and MK2.5 have no current kit. Prusa’s “MK2.5S+” article lists parts sold separately and calls it “not an official upgrade.”

How much is a used Prusa MK3S worth?

Prusa’s own prices put a ceiling on it. On 2 November 2026, a new MK4S costs $999 assembled or $709 as a kit, and the kit that turns an MK3S into an MK4S costs $629. Above $370, a used MK3S plus that kit costs more than a new assembled MK4S; above $80, more than a new MK4S kit.

The MK3S launched in February 2019 at $749 as a kit, the MK3’s price. The MK3S+ followed in November 2020 at $999 assembled, and Prusa cut it to $899 assembled and $649 as a kit on 29 March 2023. Kit production ended on 29 February 2024, and Prusa expected assembled stock to last about two more months. It said support and spare parts would continue.

Against the MK4S record, the MK3S+ record lacks input shaping, the load-cell automatic Z offset, quick-swap nozzles and any connection beyond an SD card. It has 210 mm of Z height to the MK4S’s 220 mm, and its hotend is rated 300 °C to 290 °C.

On a given unit, deduct what the checklist above says it lacks, and credit extras such as an MMU2S, spare sheets or a kit already fitted with its invoice.

What should you check on each used Prusa model?

Start from the model’s record and its successor’s price, then check what varies between units: the cooling fan and firmware printer type on an MK4, the kit fitted on an MK3.5S or MK3.9S, the Wi-Fi module on a MINI+, the revision on a CORE One and the toolhead count on an XL.

Prusa MK4S and MK4

The MK4S launched in August 2024 at $1,099, the MK4’s price in March 2023. Both have the Nextruder with a load cell and 0.9° X/Y motors. The MK4S adds a 360° cooling fan with a redesigned shroud and a high-flow CHT nozzle. The MK4-to-MK4S kit comes in two versions by xLCD revision, so check an MK4’s screen electronics before ordering.

Prusa MK3.5S and MK3.9S

Both are MK3 frames converted with the kits in the table above; ask for the kit invoice to confirm which. The MK3.5S keeps the MK3S extruder and V6 hotend, sets the first layer by manual Z and builds 250 × 210 × 210 mm. The MK3.9S has the Nextruder and load cell on the original 1.8° X/Y motors, for 250 × 210 × 220 mm.

Prusa MINI and MINI+

The MINI+ launched in November 2020 at $399, $50 more than the MINI it replaced, and is still sold new. It swapped the MINI’s M.I.N.D.A. sensor for a SuperPINDA probe, and Prusa’s MINI-to-MINI+ kit is that probe ($28.99, out of stock on 2 November 2026). Wi-Fi is an optional module on the MINI+, so check whether it is fitted. Small 3D printers lists others of its 180 × 180 × 180 mm size.

Prusa CORE One, CORE One+ and CORE One L

The CORE One shipped from January 2025 at $1,199, became the CORE One+ on 27 November 2025, and gave way to the CORE One+ (Gen 2) on 13 August 2026. To tell them apart, the CORE One+ adds an automatic top vent and the Gen 2 adds GT1.5 belts and a nozzle wiper. The CORE One L launched at $1,799 in November 2025, and its kit adds the CORE One L+’s belts and wiper.

Prusa XL

The XL launched at $2,499 with one toolhead in March 2023. The XL+ replaced it in August 2026 and costs $2,299 with one toolhead, $2,980 with two and $3,899 with five. Both take up to five toolheads, so count the heads: Prusa’s single-to-dual upgrade costs $679. The one-head XL-to-XL+ kit needs Dwarf toolhead boards marked 08 or higher; boards marked 07 or lower must be replaced. The original XL enclosure fits the XL+ but will not reach the new one’s 50 °C.