Prusa MK4 Review — Still Worth It in 2026?

The Prusa MK4 launched in March 2023 as the long-awaited successor to the MK3S+. It introduced a completely redesigned extruder (the Nextruder), a load-cell bed leveling system, 32-bit Buddy electronics, a color touchscreen, Wi-Fi, input shaper, and pressure advance. It was the most significant leap in Prusa's i3 lineage since the original MK3.

Then, in late 2024, Prusa released the MK4S — a targeted hardware refresh that added a Bondtech CHT-style nozzle and improved part cooling. The MK4S is the version Prusa now sells new, and it is the one most reviews focus on.

But the MK4 did not disappear. Thousands of users still own one — kit-built or assembled — and will for years. The MK4 to MK4S upgrade costs about $99, which is not nothing. And used MK4s are now available at significantly reduced prices, making them a legitimate option for buyers who missed the original launch.

This review is for those users: people who own an MK4 and are weighing the upgrade, and people considering a used MK4 in 2026. The MK4 is a genuinely excellent printer. It also has real limitations that no amount of loyalty to Prusa should obscure.

Specs at a Glance

Specification	Prusa MK4
Build volume	250 x 210 x 220 mm
Max print speed	500 mm/s (theoretical)
Max acceleration	4,000 mm/s²
Layer resolution	50 microns (0.05 mm) minimum
Nozzle	Standard brass 0.4 mm (E3D-compatible)
Extruder	Nextruder (direct drive)
Bed leveling	Automatic (load cell, 9-point mesh)
Filament sensor	Yes
Power recovery	Yes
Frame	Open (no enclosure included)
Connectivity	USB, Wi-Fi, Ethernet
Firmware	PrusaFirmware Buddy (open-source)
Kit price (at launch)	~$799
Assembled price (at launch)	~$1,099
Multi-material option	MMU3 ($299 kit / $359 assembled)

The MK4 and MK4S share the same frame, electronics, extruder body, and motion system. The differences are concentrated in the hotend: the MK4S has a CHT-style nozzle and improved part cooling fan placement. Everything else is identical.

MK4 vs MK4S — Should You Upgrade?

This is the question every MK4 owner faces. The honest answer: it depends on what you print and how fast you want to print it.

What the MK4S Actually Adds

The MK4S upgrade kit ($99 for existing MK4 owners) includes:

• Bondtech CHT nozzle: Splits the filament melt path into three channels, increasing volumetric flow from ~16 mm³/s to ~24 mm³/s — a 50% improvement. This is the most impactful change.
• Revised part cooling: More airflow, better directed. Improves overhang performance and allows the printer to maintain quality at higher speeds.
• Firmware profiles tuned for the new hardware: Prusa ships optimized speed profiles that take advantage of the CHT nozzle's melt rate.

When the Upgrade Is Worth It

• You regularly print large objects where print time is measured in hours, not minutes. The MK4S will be 20–40% faster on those jobs.
• You print flexible or detailed parts where cooling quality matters.
• You want the best possible version of the platform you already own.

When to Skip the Upgrade

• You print primarily at 0.2 mm layer height in PLA at standard speeds. The MK4 handles this perfectly and the MK4S will not produce noticeably better results.
• You are considering a used MK4. At $400–500 used, the MK4 + the $99 upgrade kit still comes in well below a new MK4S assembled at $1,099. Buy used, upgrade if needed.
• You are on the fence about the entire platform. If Bambu Lab is calling, spend the $99 elsewhere.

The MK4 without the upgrade is not a slow printer. It is slower than the MK4S, and slower than Bambu. But it produces excellent print quality, and for most users the speed difference is a convenience issue, not a practical blocker.

Print Quality

This is where the MK4 earned its reputation and why it remains competitive in 2026.

Dimensional Accuracy

The MK4's load-cell automatic bed leveling is exceptional. The system applies a 9-point mesh that compensates for bed warping across the entire print surface, and the first layer adhesion on the textured PEI sheet is consistent from print to print without manual adjustment. Dimensional accuracy sits within ±0.1 mm on most test geometries — as good as any consumer FDM printer available.

Surface Finish

The Nextruder's direct drive configuration and the pressure advance implementation produce clean, consistent surfaces with minimal blobs at start and stop points. Seam placement on the MK4 is handled well by PrusaSlicer's aligned seam option. The textured PEI plate leaves a matte finish on the bottom layer that looks intentional rather than accidental.

At 0.1 mm layer height, layer lines are barely visible on curved surfaces. At 0.2 mm — the standard — the MK4 produces results that most users would consider indistinguishable from the MK4S at the same settings, because the limiting factor at that layer height is geometry and slicer settings, not the nozzle's melt rate.

Overhangs and Bridging

At standard print speeds, the MK4 handles overhangs to about 45–50 degrees without supports on PLA. Bridges up to 60 mm print cleanly. These are not the numbers the MK4S achieves — the improved cooling on the MK4S pushes overhang performance to 55–60 degrees — but they are good enough for the vast majority of prints. If you regularly print challenging overhangs, the MK4S upgrade is worth considering. For most users, it is not a daily limitation.

Build Quality and Long-Term Reliability

Prusa's reputation for long-term reliability is not marketing. The MK3S+ has been in continuous production since 2019, and Prusa still sells spare parts, provides firmware updates, and actively supports the printer. The MK4 is on the same trajectory.

The MK4's steel frame is solid. The Nextruder is a significant improvement over the original i3 extruder — it is more rigid, handles flexible filaments better, and has fewer failure modes. The load-cell bed leveling eliminates the probe offset drift that was a persistent annoyance on the MK3S+.

The typical MK4 lifespan, maintained properly, is well over five years. Wear items — the nozzle, PTFE coupler, PEI sheet surface — are all cheap and available directly from Prusa or third-party suppliers. The Buddy electronics board is replaceable. The Nextruder components are individually available. You will never be in a position where one broken part makes the printer unrepairable.

This stands in contrast to Bambu Lab, where proprietary electronics and firmware mean that long-term repairability depends entirely on whether Bambu continues to support the product. That is a real risk over a five-to-seven-year ownership horizon.

Speed Reality

The MK4 introduced input shaper (resonance compensation) and pressure advance to the Prusa line — two features that were already standard on Bambu printers. Both features work well and meaningfully reduce ringing artifacts at higher speeds.

With input shaper enabled, the MK4 can push outer wall speeds to 100–150 mm/s while maintaining clean print quality. Without it, speeds above 80 mm/s produce visible ringing on sharp corners.

But let us be honest about where the MK4 stands in the current market:

Metric	Prusa MK4	Prusa MK4S	Bambu Lab P1S
Max speed	500 mm/s	600 mm/s	500 mm/s
Max acceleration	4,000 mm/s²	4,000 mm/s²	6,000 mm/s²
Typical wall speed	80–120 mm/s	150–200 mm/s	200–300 mm/s
Volumetric flow	~16 mm³/s	~24 mm³/s	~28 mm³/s
Benchy time (speed mode)	~28–35 min	~18–22 min	~16–18 min

The MK4 is meaningfully slower than both the MK4S and the Bambu P1S in practice. The difference comes down to volumetric flow: the standard brass nozzle on the MK4 cannot melt filament fast enough to feed the higher-acceleration motion system at its limits. The printer reaches its melt-rate ceiling before it reaches its mechanical ceiling.

For a 20-minute print, this does not matter. For a 10-hour print, the difference between 28 minutes and 18 minutes per Benchy scales to real saved time on the full job. If you print all day, the MK4S or a Bambu printer will save you meaningful hours per week.

Open Source and Repairability

The MK4 runs PrusaFirmware Buddy — fully open-source, hosted on GitHub, accepting community contributions. The complete hardware design (CAD files, schematics, BOMs) is public. PrusaSlicer, the recommended slicer, is also open-source and one of the best maintained slicers in the industry.

This matters for three reasons:

1. Longevity. Even if Prusa Research stops existing, the community can maintain the printer indefinitely. This has already happened with printers like the Mendel and the original i3 — communities kept them alive for years after active development stopped.
2. Repairability. Every component has a documented repair procedure. The MK4 manual is over 200 pages and covers disassembly to the individual screw level.
3. Modification. The community creates and shares mods constantly — improved cooling ducts, cable management solutions, enclosure brackets, and more. Printables.com is full of MK4 community modifications.

No current competitor matches this. Bambu Lab firmware is closed. Creality's ecosystem is partially open but inconsistently documented. Prusa is the only consumer printer brand with a genuine commitment to open hardware.

Material Compatibility

The MK4's direct-drive Nextruder handles a wide range of materials. The open frame is the main limitation for high-temperature materials.

Material	Compatibility	Notes
PLA	Excellent	Best results out of the box
PETG	Excellent	Textured PEI plate recommended
ABS	Good (with enclosure)	Open frame causes warping and layer delamination
ASA	Good (with enclosure)	Same limitation as ABS
TPU	Excellent	Direct drive handles flexible filament reliably
Nylon (PA)	Good (with enclosure and dry box)	Moisture sensitive; requires dry storage
PC	Fair (with enclosure)	Pushes the limits of the standard hotend
PVA (soluble)	Excellent	With MMU3 for soluble support structures

PLA, PETG, and TPU work without any modifications or aftermarket additions. ABS and ASA are technically printable but benefit significantly from an enclosure — draft-free conditions matter more than the printer itself for those materials. If you primarily print engineering materials, the Bambu P1S's built-in enclosure is a real advantage.

MK4 vs Bambu P1S vs MK3S+

Feature	Prusa MK4	Bambu Lab P1S	Prusa MK3S+
Build volume	250×210×220 mm	256×256×256 mm	250×210×210 mm
Enclosure	No	Yes	No
Speed (practical)	Moderate	Fast	Slow
Print quality	Excellent	Excellent	Very good
Open source	Fully	No	Fully
Repairability	Excellent	Limited	Excellent
Direct drive	Yes	Yes	Yes
Multi-material	MMU3 ($299)	AMS 2 Pro ($299)	MMU2S ($299)
Wi-Fi / remote	Yes	Yes	PrusaLink add-on
New price (approx.)	$500–600 used	$500 new	$599 new (kit)
Long-term support	Proven	Unproven	Proven (6+ years)

The MK4 improves on the MK3S+ in almost every category: faster, more accurate bed leveling, better electronics, better extruder, quieter operation. The MK3S+ remains a capable printer but it is a previous generation in every meaningful way.

Against the Bambu P1S: the Bambu wins on speed, enclosure, and price. The MK4 wins on open source, repairability, and long-term support confidence. Print quality is roughly equivalent between the two — both produce excellent results, with the MK4 holding a narrow edge on dimensional accuracy and surface consistency.

Software — PrusaSlicer Advantage

PrusaSlicer is, by most expert consensus, the best open-source FDM slicer available. The default profiles for Prusa hardware are exceptional — thoroughly tested, regularly updated, and tuned to the actual printer rather than theoretical specifications.

Key PrusaSlicer advantages relevant to MK4 users:

• Variable layer height: Automatically adjusts layer height based on geometry, reducing print times without sacrificing quality on flat surfaces.
• Organic supports: Automatically generated, tree-style supports that are easier to remove and use less material than traditional grid supports.
• Multi-material painting: For MMU3 users, the ability to paint multi-color assignments directly on the model surface is intuitive and powerful.
• Input shaper calibration integration: PrusaSlicer includes profiles pre-tuned for the MK4's resonance compensation settings.
• Active development: Prusa ships slicer updates regularly. The software improves continuously, and those improvements benefit existing hardware.

BambuStudio — Bambu Lab's slicer — is more polished in terms of UI and out-of-the-box experience. But for fine-tuning, material profiles, and advanced functionality, PrusaSlicer is deeper and more capable.

For tuned settings, see our Prusa MK4 settings guide.

Who Should Buy a Used/New MK4 in 2026

Buy a used MK4 if:

• You want a proven, repairable printer at a fair price. A well-maintained used MK4 at $400–500 is an excellent value. Add the $99 MK4S upgrade kit later if you decide you need it.
• Open source and repairability matter to you. Same story as the MK4S — the platform is uniquely well-supported.
• You are upgrading from an MK3S+. The MK4 is a genuine improvement in every category. The upgrade path is straightforward.
• You print primarily PLA and PETG. These materials work perfectly on the MK4 out of the box, and the print quality will satisfy most users.

Buy a new MK4S instead if:

• You want the best current version of the platform. The MK4S is only slightly more expensive new than a used MK4 with the upgrade kit, and it arrives already upgraded.
• Speed matters. The CHT nozzle difference is real. If you print volume, get the MK4S.
• You are a first-time Prusa buyer. There is no reason to start with the older version when the newer one is available at competitive prices.

Buy a Bambu Lab P1S instead if:

• Budget is the primary constraint. The P1S at $500 new delivers comparable print quality with an enclosure.
• You need ABS or ASA regularly. The enclosed Bambu is a better starting point for engineering materials.
• Setup complexity is a concern. Bambu printers are closer to plug-and-play. The MK4 kit takes 8–12 hours to assemble.
• Speed is a top priority. Bambu is faster in practice.

Cost of Ownership and Spare Parts

This is one of the MK4's genuine long-term advantages. Every component is available individually from Prusa's e-shop:

Part	Approximate Cost
Nozzle (brass 0.4 mm)	$3–5
Nextruder PTFE coupler	$5
Textured PEI sheet	$30
Smooth PEI sheet	$25
Extruder idler	$8
Buddy main board	$60–80
Hotend complete assembly	$40–50
Full Nextruder assembly	$80–100
Heatbed assembly	$70–90

Typical annual consumable cost for moderate use: $20–40 (nozzle replacements and PEI sheet re-seasoning). A major component failure — a board or hotend — costs $50–90 and is a two-hour replacement. There is no scenario where the MK4 becomes unrepairable due to part availability.

Compare this to Bambu Lab, where proprietary parts are sold exclusively through Bambu's own store at Bambu's own prices. As of 2026, Bambu spare parts are reasonably available, but the trajectory of availability for a 3-year-old Bambu printer versus a 3-year-old Prusa printer is not the same historical bet.

Final Verdict

The original Prusa MK4 is a genuinely excellent printer that holds up well in 2026 — not because nothing better exists, but because it delivers excellent print quality, long-term reliability, and a uniquely repairable, open-source ecosystem that no competitor matches.

Its weaknesses are real. It is slower than the MK4S and significantly slower than Bambu's current lineup. The open frame limits high-temperature material printing without aftermarket additions. At new prices, it was expensive relative to what Bambu offered. At used prices, those objections largely evaporate.

If you own an MK4 today: keep it. Consider the $99 MK4S upgrade if speed matters to your workflow. The printer will serve you reliably for years, supported by a community and a manufacturer with a proven commitment to long-term support.

If you are buying new and considering a first Prusa: the MK4S is the version to buy — the difference in price over a used MK4 is small, and you get the full current hardware without needing to source or install the upgrade kit.

If you are buying used and budget is a real consideration: an MK4 at $400–500 in good condition is one of the best value propositions in consumer 3D printing in 2026. It produces results that will satisfy most users, parts are cheap and plentiful, and you can always upgrade to MK4S hardware later for $99.

The MK4 is not the fastest printer. It is not the cheapest printer. It is the printer you buy when you want to own it for five years, fix it yourself, and trust that it will still be supported when you need a part in 2029.

Find models to test your MK4 on 3DSearch, where you can search across all major model repositories to find designs that push your printer's capabilities.

Happy printing!