Printer Filament Guide

Best Filament for the Prusa MK4S

The open-frame bed-slinger that turned Prusa reliability into a 290 C high-flow workhorse.

Last updated: June 2026

The MK4S is the mid-2024 refresh of the MK4 and Prusa's current i3-style bed-slinger. It keeps the open A-frame, the load-cell Nextruder, and the 250 × 210 × 220 mm bed, then adds a high-flow brass CHT nozzle plus a 360-degree print-cooling shroud so it can push real speed without trashing overhangs. The hotend tops out at 290 C, and the spring-steel sheets (textured, smooth, satin) swap in seconds. You can buy it as a kit or assembled.

What the Prusa MK4S prints well

Recommended materials for this printer:

PLA PLA+ PETG TPU

No enclosure, so ABS, ASA, PC and nylon will warp and crack. Stick to PLA, PLA+, PETG and TPU for reliable prints. Carbon- and glass-fibre composites also need a hardened nozzle first.

Cheapest filament for the Prusa MK4S right now
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With the open frame, the MK4S lives happily on PLA, PETG, PLA-CF/PETG-CF and TPU all day. ASA and ABS print fine for small-to-medium parts, but with no enclosure you'll fight warping and layer splitting on tall prints unless you add the optional Prusa enclosure or box it in. The stock nozzle is brass, so carbon- and glass-filled filaments will chew it. Fit a hardened steel or ObXidian-style nozzle before running abrasives.

Prusa MK4S specs that affect filament

Build volume
250 × 210 × 220 mm
Enclosure
Open frame
Heated chamber
No
Extruder
Nextruder (direct drive)
Max hotend temp
290°C
Stock nozzle
High-flow Prusa brass CHT nozzle, 0.4 mm (swappable)
Abrasive-ready (CF/GF)
Needs hardened nozzle
Multi-material
MMU3 (optional, up to 5 materials)

This is the printer for someone who wants a dependable, well-documented machine with the best slicer profiles in the business and isn't chasing an enclosed chamber. Add the MMU3 later for up to five-material printing. If your shelf is mostly PLA, PETG and the occasional TPU, the MK4S is hard to beat.

Filament notes for the Prusa MK4S

  • PLA, PETG and TPU are the comfort zone: open frame, 360-degree cooling, dialed-in Prusa profiles.
  • Stock nozzle is brass CHT (high-flow), so the melt rate is great but it wears fast on CF/GF filament. Swap to hardened steel for abrasives.
  • ASA/ABS print but want the optional enclosure to avoid warping and cracking on larger parts, since the open frame offers no chamber heat.
  • 290 C hotend covers PLA, PETG, ASA, ABS, ASA-CF and most PA-CF. It isn't built for high-temp PC blends or PEEK/PEI.
  • Running the MMU3? Prusa recommends the standard (non-CHT) 0.4 mm nozzle for cleaner multi-material tip shaping.
  • Textured PEI sheet is the default for PLA/PETG/ASA; use a glue stick or the satin sheet for PETG to avoid over-adhesion.
  • Dry your filament. PETG, TPU and any -CF/-GF blend print far better from a dry box on a fast machine like this.
How SpoolHound tracks prices

The deals above are filtered to the materials the Prusa MK4S handles, aggregated from multiple retailers daily and normalised to cost per kg, so the cheapest in-stock option is always on top. Prices refresh every 24 hours and are region-aware, so switch your region in the nav. Click through to the retailer to confirm the live checkout price.

Frequently Asked Questions

Can the Prusa MK4S print ABS and ASA?
Yes, but it's an open-frame printer with no heated chamber, so larger ABS/ASA parts can warp or split. Add the official Prusa enclosure (or box it in) and keep drafts off the bed for reliable results. Small and medium parts are usually fine out of the box.
Does the MK4S handle carbon-fiber filament?
It can, but the stock brass CHT nozzle isn't abrasion-resistant and will wear quickly on CF/GF filaments. Fit a hardened steel or ObXidian-style 0.4 mm+ nozzle first, and expect to use a larger orifice for chopped-fiber blends.
What is the hottest the MK4S nozzle gets?
290 C at the nozzle and up to 120 C on the bed. That covers PLA, PETG, ASA, ABS and most carbon/glass-filled nylons, but not true high-temp engineering materials like PC-heavy blends or PEEK.
Can the MK4S print multiple colors?
Yes, with the optional MMU3 unit it prints up to five materials or colors from a single nozzle. Prusa suggests the standard (non-high-flow) 0.4 mm nozzle when running the MMU3 for cleaner filament tips and fewer jams.

Different printer? See filament by printer for the rest of the lineup, or browse cheapest filament by material.