Prusa MK4 Review (2026): 11 Months In: The Reliability

Why you should trust this review

I bought the MK4 with my own money, fully assembled, to be a workhorse I could rely on, not a review loaner from Prusa. I print regularly and have used the budget CoreXY machines everyone compares it to, so I can be honest about where the MK4 loses on paper and where it wins in the long run. Nobody at Prusa knew I was writing this.

How we evaluated

Over eleven months of regular use I ran the MK4 through more than 80 prints across materials and sizes. I tested the load cell first layer calibration by watching whether first layers came out usable without manual intervention, measured dimensional accuracy on 20 mm calibration cubes over time, pushed print speed to find where ringing appeared, tried the open source firmware flexibility including community mods, and used Prusa support and the parts catalog to judge real world serviceability.

First layer calibration, the daily quality of life win

The MK4’s load cell first layer calibration is the feature you feel every single print. Across more than 80 prints it produced first attempt usable first layers without me crouching at the nozzle adjusting a baby step, which is exactly the kind of reliability that makes a printer something you trust to start and walk away from. Dimensional accuracy backed that up, 20 mm cubes held within about a tenth of a millimeter across eleven months, so parts that need to fit, fit. For a workhorse, this consistency is the whole point.

Software, firmware, and long term serviceability

PrusaSlicer is best in class and the firmware is fully open source, which means the machine supports community mods, including alternative firmware if you want to go that route, rather than locking you into a closed ecosystem. The bigger long game advantage is parts, Prusa sells individual replacement parts for years, including for legacy printers, so the MK4 is a machine you maintain and upgrade rather than replace. That is the quiet reason it justifies its price over the years, you are buying into support that does not disappear.

Speed, multi material, and the honest tradeoffs

The MK4 loses the speed argument and I will not pretend otherwise. Its bedslinger motion system limits useful print speed to roughly 200 mm/s before ringing shows up, so a Bambu P1S simply prints faster, and the MK4 costs more whether you buy it assembled or as a kit. The MMU3 multi material upgrade is also fiddly next to Bambu’s AMS, expect occasional filament jams. And there is no enclosure included, so ABS and ASA need an aftermarket enclosure. None of these break the machine, but they are real costs of choosing serviceability over speed.

Who should buy the Prusa MK4?

Buy it if you want a reliable workhorse you will own and maintain for years, you value dead simple first layers and best in class slicing, and Prusa’s long term parts and support matter more to you than raw speed.

Skip it if you want the fastest printer for the money, you need hassle free multi material printing where Bambu’s AMS is smoother, or you want an enclosed printer for ABS out of the box.

The verdict

The MK4 is a long term decision dressed up as a printer purchase. Across eleven months its load cell calibration gave me consistent first layers without fuss, it held tight dimensional accuracy, and its open firmware plus unmatched parts availability make it a machine you keep running for years. It is more expensive than a Bambu P1S and its bedslinger motion caps useful speed, and the multi material upgrade is fiddly. If you think in years and value serviceability over speed, the MK4 is the smarter buy, and I would choose it again.