Original Prusa MK4S

# Original Prusa MK4S

Overview

The Original Prusa MK4S is an open-frame Cartesian FDM/FFF printer focused on dependable print quality, straightforward maintenance, offline operation, and long-term upgradeability. It keeps the proven 250 × 210 × 220 mm MK4 platform while adding a 360° cooling system, a 0.4 mm high-flow Prusa brass CHT nozzle, updated firmware, and faster print profiles.

The MK4S uses Prusa's Nextruder direct-drive extruder with a 10:1 planetary gearbox and load-cell sensing for automatic first-layer calibration. The hotend reaches 290°C, the heatbed reaches 120°C, and the official layer-height range is 0.05–0.30 mm.

Prusa does not publish one universal maximum print speed for the MK4S. Its speed advantage comes from the high-flow CHT nozzle, Input Shaper, optimized profiles, and the redesigned part-cooling system rather than a single headline mm/s number.

The printer supports common materials such as PLA, PETG, Flex/TPU, PVA, PC, PP, CPE, and PVB directly. Prusa recommends its optional enclosure for ABS, ASA, HIPS, PA and other materials that benefit from a more stable thermal environment. Abrasive carbon-filled filaments require a suitable wear-resistant nozzle rather than the standard brass CHT nozzle.

For current specifications and ordering, see the official Original Prusa MK4S product page. For multi-material printing, see the official MMU3 upgrade.

Key Strengths

• 250 × 210 × 220 mm build volume
• 0.05–0.30 mm layer-height range
• 290°C maximum nozzle temperature
• 120°C maximum bed temperature
• 0.4 mm high-flow Prusa brass CHT nozzle
• Nextruder direct-drive extrusion
• 10:1 planetary gearbox
• 360° high-performance cooling
• Automatic load-cell first-layer calibration
• Automatic mesh bed leveling
• Input Shaper support
• Power Panic recovery
• Filament sensing
• Fan RPM monitoring
• Ethernet, Wi-Fi, NFC-assisted setup and USB
• Fully offline operation supported
• Prusa Connect and Prusa mobile app support
• Optional MMU3 five-filament printing
• Optional Original Prusa Enclosure
• Official MK4S-to-CORE One+ conversion path
• Open-source firmware and software ecosystem
• UL GREENGUARD certification highlighted by Prusa

Best For

1. Reliable everyday PLA and PETG printing
2. Functional prototypes
3. Engineering parts
4. Flexible filament
5. Education and laboratories
6. Small production farms
7. Users who value repairability and open hardware
8. MMU3 multi-color printing
9. Buyers who want a later CORE One+ conversion path
10. Workshops that prefer local/offline operation

Technical Specifications

Prusa does not publish one simple maximum print-speed figure in the main MK4S specification table. Real speed depends on nozzle, filament, profile, geometry, layer height, and required surface quality.

What Changed From MK4 to MK4S?

The Original Prusa MK4S vs MK4 comparison is mainly about cooling, extrusion flow, firmware, and quality-of-life improvements rather than a completely new motion platform.

Prusa lists the principal MK4S changes as:

• New 360° cooling system
• High-flow nozzle as standard
• Improved print speed
• Updated print profiles
• Improved print quality
• Native Prusa mobile-app support
• NFC-assisted Wi-Fi setup
• Updated printed and injection-molded parts
• Optional GPIO and accelerometer accessories

The MK4S keeps the same 250 × 210 × 220 mm build volume and Nextruder architecture, so MK4 owners gained a clear hardware upgrade path without replacing the entire printer.

For buyers choosing today, the MK4S is the more refined version and the better reference point for current Prusa open-frame printing.

High-Flow CHT Nozzle

The standard MK4S nozzle is a 0.4 mm Prusa brass CHT high-flow nozzle.

CHT, or Core Heating Technology, splits the filament flow inside the nozzle so heat reaches more of the filament cross-section. The goal is higher melt capacity without simply raising temperature.

This helps the MK4S maintain extrusion flow at faster profile speeds and is a major reason Prusa improved print times without publishing an unusually high motion-speed headline.

The brass CHT nozzle is not intended for long-term abrasive carbon- or glass-fiber use. A hardened or otherwise wear-resistant nozzle should be fitted for filled composites.

360° Cooling and Overhang Printing

The MK4S redesign introduced a high-performance turbine fan and a 360° cooling duct around the nozzle.

Prusa demonstrates overhangs up to 75° without supports under its test conditions. Real results depend on material, orientation, layer height, speed, and model geometry, so this should be treated as a demonstrated manufacturer capability rather than a guarantee for every model.

The stronger cooling is also helpful for PLA and flexible materials, where clean overhangs can reduce the need for difficult-to-remove support structures.

Nextruder and Automatic First Layer

The Nextruder combines direct-drive extrusion, a 10:1 planetary gearbox, and an integrated load cell.

During calibration, the nozzle touches the build surface directly. Because the sensing point is the nozzle itself, there is no separate probe-to-nozzle XY offset.

This allows automatic mesh bed leveling and first-layer calibration while keeping the filament path compact for flexible materials.

Automatic calibration still depends on a clean sheet, correct material profile, and normal mechanical maintenance.

Material Compatibility

Prusa's current MK4S specification table lists the following materials directly:

• PLA
• PETG
• Flex / TPU
• PVA
• PC
• PP
• CPE
• PVB

With the Original Prusa Enclosure and filtration add-on, Prusa also lists:

• ABS
• ASA
• HIPS
• PA / Nylon

Useful compatible materials for MK4S-class printing include Prusament PETG, Prusament TPU 95A, Prusament ASA, and Prusament PC Blend Carbon Fiber.

Carbon-Fiber Filaments

The printer can process carbon-filled materials when the filament temperature requirements fit the MK4S hardware, but abrasive fibers require a wear-resistant nozzle.

Prusament PC Blend Carbon Fiber is within the MK4S hotend temperature range, and Prusa states that the material itself does not require an enclosure, but a hardened nozzle is mandatory because the carbon fibers are abrasive.

Optional Original Prusa Enclosure

The MK4S is open-frame by default.

The Original Prusa MK4/S Enclosure is passively heated by the printer rather than using an independent chamber heater.

Prusa publishes an enclosure temperature of up to about 45°C in its printer comparison material. The enclosure is most useful for ABS, ASA, PA/Nylon, PC and similar materials that benefit from reduced drafts and a more stable ambient temperature.

Optional advanced filtration is also available.

MMU3 Five-Color and Multi-Material Printing

The optional MMU3 gives MK4S up to five filament inputs through one hotend.

Prusa currently states 25–35 seconds per filament change in its workflow and promotes lower waste than many other single-nozzle systems.

Standard Nozzle vs High-Flow Nozzle With MMU3

Prusa specifically recommends the standard-flow 0.4 mm nozzle for the best MMU3 material efficiency.

The high-flow CHT nozzle works with MMU3, but its larger melt volume can require more flushing for clean color transitions. Prusa therefore includes a standard nozzle with standalone MK4S MMU3 kits and supplies both nozzle types in relevant bundles.

This distinction matters for buyers comparing Prusa MK4S MMU3 vs Bambu AMS lite or other single-nozzle color systems.

Prusa Connect, Offline Operation and Privacy

MK4S supports Ethernet, the removable ESP Wi-Fi module, NFC-assisted setup, USB printing, Prusa Connect and the Prusa mobile app.

Prusa also supports fully offline setup and operation. The Wi-Fi module can be physically removed when network access is undesirable.

That makes MK4S particularly relevant to schools, laboratories, engineering teams and businesses with tighter network or intellectual-property requirements.

MK4S to Prusa CORE One+ Upgrade Path

Prusa sells an official MK4S to Prusa CORE One+ conversion kit, allowing owners to reuse many existing components while moving to a fully enclosed CoreXY platform.

The resulting CORE One+ adds:

• Fully enclosed CoreXY architecture
• Larger 250 × 220 × 270 mm build volume
• Active chamber control up to 55°C
• More compact footprint
• Better conditions for ABS, ASA, PA and other temperature-sensitive materials

See the indexed Prusa CORE One+ for the finished platform.

Comparison Table: MK4S vs Current Desktop Alternatives

The MK4S is not the obvious choice for maximum build volume or headline motion speed. Its case is stronger around maintenance access, open-source software and firmware, offline operation, tuned Prusa profiles, MMU3 support, and the ability to convert to a CORE One+ later.

Original Prusa MK4S vs Bambu Lab A1

The Original Prusa MK4S vs Bambu Lab A1 comparison is one of the most common open-frame desktop choices.

The Bambu Lab A1 offers a 256 × 256 × 256 mm build volume, 500 mm/s maximum toolhead speed, 300°C hotend, 100°C bed, automatic calibration, active flow-rate compensation, and optional four-color AMS lite.

MK4S has a smaller build volume but a hotter 120°C bed, the Nextruder load-cell system, a high-flow CHT nozzle, Ethernet, full offline operation, and an open upgrade/repair ecosystem.

For multi-color printing, A1 uses AMS lite with up to four filaments, while MK4S MMU3 handles up to five.

Choose Bambu Lab A1 when larger build volume, streamlined automation, and the Bambu ecosystem are the priority.

Choose MK4S when repairability, PrusaSlicer, offline operation, Ethernet, MMU3, flexible-material handling, and long-term upgradeability matter more.

Original Prusa MK4S vs Prusa CORE One+

The MK4S vs Prusa CORE One+ decision is mainly open-frame simplicity versus enclosed CoreXY capability.

The Prusa CORE One+ provides a 250 × 220 × 270 mm build volume, active chamber control up to 55°C, and an enclosed CoreXY architecture.

Both use the Nextruder family, a 290°C hotend, 120°C bed, load-cell first-layer calibration, Input Shaper, Ethernet, Wi-Fi and the wider Prusa ecosystem.

MK4S is easier to access mechanically and remains the lower-cost entry point. CORE One+ is better for ABS, ASA, Nylon and other materials that benefit from an actively controlled enclosure.

Original Prusa MK4S vs Bambu Lab P2S

The Original Prusa MK4S vs Bambu Lab P2S comparison separates an open, highly serviceable Cartesian printer from a newer enclosed CoreXY platform.

The Bambu Lab P2S offers a 256 × 256 × 256 mm build volume, 300°C nozzle, 110°C bed, higher headline motion speed, an enclosure, integrated camera monitoring, and the Bambu AMS ecosystem.

MK4S counters with a 120°C bed, a simpler open mechanical layout, Prusa's Nextruder and CHT system, extensive offline operation, Ethernet, open-source firmware/software, and direct conversion to CORE One+.

Choose P2S when enclosure-based engineering-material printing and Bambu automation are priorities.

Choose MK4S when serviceability, openness, local control, and upgradeability matter more than an enclosed CoreXY chassis.

Original Prusa MK4S vs MK4

For buyers comparing Prusa MK4S vs MK4, the newer MK4S is not a different size class; it is the refined version of the same core platform.

Its main improvements are 360° cooling, the standard high-flow CHT nozzle, faster tuned profiles, improved overhang performance, native Prusa mobile-app support, NFC-assisted setup, and updated parts.

Existing MK4 owners could upgrade rather than replace the printer, which reflects Prusa's long-term platform strategy.

Which Original Prusa MK4S Alternative Fits Best?

• Bambu Lab A1: better for a larger open-frame build volume and streamlined Bambu automation.
• Prusa CORE One+: better for active chamber control and enclosed engineering-material printing while staying in the Prusa ecosystem.
• Bambu Lab P2S: better for an enclosed CoreXY platform with integrated camera monitoring and AMS expansion.
• MK4S: strongest when easy maintenance, offline operation, PrusaSlicer, MMU3, flexible-material handling, and a future CORE One+ conversion path matter most.

Price and Availability

Prusa currently lists the Original Prusa MK4S kit from US$729, approximately €629 in Europe, £538 in the UK, C$1,013 in Canada, A$1,030 in Australia, ₹69,772 in India, and AED 2,677 in the UAE. The assembled version is priced higher. Actual prices may differ by region due to VAT or local taxes, import duties, exchange rates, shipping costs, availability, and promotions.

Limitations and Practical Considerations

• Open-frame construction is less suitable for large ABS, ASA, PA and other high-shrink parts without the optional enclosure.
• The optional Original Prusa Enclosure is passive rather than actively heated.
• The standard brass CHT nozzle is not appropriate for long-term abrasive carbon/glass-fiber use.
• Prusa does not publish one universal maximum print-speed number for MK4S.
• MMU3 still uses one hotend, so multi-color printing requires filament changes and purge.
• The high-flow CHT nozzle can increase MMU3 purge demand; Prusa recommends the standard-flow nozzle for best efficiency.
• MK4S has a smaller build volume than Bambu Lab A1 and P2S.
• Camera monitoring is optional rather than integrated into the base printer.
• Physical spring-steel sheet dimensions are not separately published in the main MK4S specification table.
• ABS, ASA, HIPS and PA are listed by Prusa in conjunction with the enclosure and filtration configuration.

Frequently Asked Questions