PrusaSlicer: Prusa's Open Source Slicer, Modes, and Features

What Is PrusaSlicer, and Who Builds It?

PrusaSlicer is slicing software built by Prusa Research, distributed for free and released as open source under the AGPL-3.0 license, as shown on its repository at github.com/prusa3d/PrusaSlicer. It turns a 3D model into machine instructions (G-code) and supports both FDM printers and mSLA resin printers, according to the same documentation.

The project started as a fork of Slic3r, one of the earliest open source slicers from the RepRap community, before being heavily rewritten and extended by the Prusa Research team across later versions. Because the full source code is public, anyone can inspect, modify, or redistribute the software under the terms of its license, which is also why several other slicers trace back to it directly.

PrusaSlicer Isn't Limited to Prusa Printers

The software ships by default with profiles for Prusa's own machines (MK4, MINI+, XL, and so on), but it also bundles preconfigured profiles for a wide range of third-party printers from other brands, and the community regularly shares additional profiles to import manually. Starting from the closest matching profile, rather than tuning every setting by hand, remains the most reliable way to get a usable first print.

For a printer without an official profile, starting from a similar machine (same nozzle, similar build volume) and adjusting from there works well in practice. Picking the right slicer for a given machine is covered in more depth on the choosing a slicer guide, worth reading before committing to one tool.

Simple, Advanced, Expert: Who Each Mode Is For

PrusaSlicer offers three interface modes, switchable from the top of the window. Simple mode hides most settings and shows only the most common ones (material, quality, infill), built for a first-time setup. Advanced mode surfaces retraction, cooling, and support settings in more detail.

Expert mode exposes the full parameter set, including organic supports, paint-on seams, and variable layer height, all covered below. Switching between modes never changes settings already in place; it only shows or hides options, which lets a user grow into more complexity gradually without rebuilding a profile from scratch.

The Features That Set PrusaSlicer Apart

Organic supports, introduced to replace the older grid-style supports, branch out from the sides of the model with a smoothed shape that automatically adapts where it is needed; per Prusa's documentation, they come off more easily, leave fewer marks on the part, and generally use less filament than classic grid supports. Paint-on supports let a user, in Advanced or Expert mode, mark on the 3D model exactly where to force or block a support with the mouse.

Variable layer height, described in Prusa's documentation, lets certain areas of the model print with thinner layers and others with thicker ones, with an automatically smoothed transition between them; this cuts print time on simple areas without sacrificing detail where it matters. PrusaSlicer also includes built-in calibration tests, such as the extrusion multiplier calibration described in its knowledge base, to tune material flow before a print run.

PrusaSlicer, OrcaSlicer, Bambu Studio: Who Forked Whom

Bambu Studio, Bambu Lab's own software, was built on top of PrusaSlicer's code before being adapted to the brand's printers. OrcaSlicer, a separate community project, in turn draws from both Bambu Studio and PrusaSlicer: per its own GitHub repository, the project "began in that same spirit, drawing from BambuStudio, PrusaSlicer, and ideas inspired by CuraSlicer and SuperSlicer," before being substantially reworked since.

That lineage shows up in the interface, which looks similar across all three, and in settings that often share the same names. OrcaSlicer's repository highlights its own built-in calibration tools (temperature tower, flow rate, retraction) and advanced seam control, presented as going further than PrusaSlicer on those specific points, while staying under the same AGPL-3.0 license. A dedicated article compares print supports across different slicers in more detail.

Running Your First Slice, Step by Step

After importing a file in STL or 3MF format, the first step is picking the right printer and nozzle profile from the dropdown at the top of the screen, then the filament profile matching the material actually loaded on the spool. The print quality profile chosen next (fine, standard, fast) largely determines the visual finish and print time.

Once those three profiles are set, the slice button calculates the toolpaths and shows an estimated print time and filament usage, viewable before exporting the G-code to an SD card, USB drive, or network connection depending on the printer model. To find ready-to-print 3D files instead of modeling one from scratch, the 3D print files page rounds up the reference platforms.

Cutting an Oversized Model: PrusaSlicer's Cut Tool

When a model is too big for the build volume, when one part of it needs a different orientation to hold up mechanically, or when printing the whole piece would call for an excessive amount of support material, PrusaSlicer includes a cutting tool, accessible by selecting the object and pressing the C key, according to its knowledge base. Planar mode slices the model along a plane you can freely position and rotate on the X, Y, and Z axes, while Dovetail mode directly generates a trapezoidal pin and socket that lock into each other.

The tool can either create two separate objects or keep both halves connected in a single file with different settings for each. It can also automatically add connectors at the cut line: a simple cylindrical plug, a removable dowel printed separately, or a snap-fit connector, each with its own shape, depth, and rotation options. This feature pairs well with choosing print supports: cutting a bulky part before printing often cuts down on support needs more effectively than pushing support settings harder.

Calibrating the Extrusion Multiplier: What It Does and When to Touch It

PrusaSlicer's extrusion multiplier adjusts how much material is actually extruded, an advanced setting Prusa recommends leaving alone on a factory-fresh printer and reserving for experienced users. Per the Prusa Knowledge Base, this software setting and the firmware's flow rate parameter (the M221 command) affect the same physical quantity but independently of each other: the total flow rate applied equals the firmware's multiplier times the slicer's multiplier.

The ideal value differs from one material to another, from one color to another, and sometimes even from spool to spool of the same filament, which is why this setting mostly needs recalibrating when switching brands often or using cheap no-name filament. Too high a flow rate shows up as scarring or visible material buildup on layers, especially the first and last ones on a part, while a slightly low flow rate leaves small gaps between lines or perimeters, a symptom not to confuse with under-extrusion caused by a mechanical problem.

Where to Find Help and Additional Profiles

Prusa's knowledge base, updated regularly, documents each setting in detail and works as a reference for understanding what a parameter actually does before changing it blind on an important part. The official Prusa forum rounds out that documentation with real-world feedback from other users, useful when a well-documented setting still doesn't explain an unexpected result on a specific printer or material.

The project's GitHub repository remains the most reliable place to track what changed from one version to the next, see how a setting's behavior evolved, or file a reproducible bug with a concrete example, ideally with the exact PrusaSlicer version and printer profile involved. For a printer whose profile still lacks a fine-tuned setting, starting from a similar third-party profile and adjusting temperature, speed, and retraction step by step is usually faster and safer than rebuilding an entire profile from a blank page.

Sources and limits

• GitHub — prusa3d/PrusaSlicer
• Prusa Knowledge Base — Organic Supports
• Prusa Knowledge Base — Paint-on supports
• Prusa Knowledge Base — Variable layer height function
• GitHub — SoftFever/OrcaSlicer
• Prusa Knowledge Base — Cut tool
• Prusa Knowledge Base — Extrusion multiplier calibration

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.