The material shrinkage calibration in Bambu Studio is one of the most overlooked parameters in the entire software. Even if you are using official Bambu Lab filament, the shrinkage value is set to 100% by default. That means the slicer applies zero compensation.
Just like flow rate and pressure advance, shrinkage compensation is critical if you want dimensionally accurate parts. I learned this the hard way. I printed a 400 × 400 mm heated-bed mount for a 3D printer I was building. After hours of printing and assembly, the mounting screws simply did not line up with the bed. Every dimension in the CAD file was correct, the printer’s linear accuracy was excellent, yet the parts still refused to fit. SNAFU ! I had completely forgotten about material shrinkage.
Why Materials Shrink
Every thermoplastic contracts as it cools from printing temperature down to room temperature. This is normal physics. The amount of shrinkage depends on:
The material type (PLA shrinks far less than ABS, ASA, or nylon)
The temperature delta between the nozzle/bed and ambient air
The specific formulation used by each manufacturer
Because different brands (and even different colors of the same brand) can have slightly different polymer blends and additives, you should recalibrate whenever you switch suppliers. Once you have a reliable profile for a given filament at a given print temperature, you usually do not need to repeat the test unless you change temperatures or drying conditions significantly.
The Simple Calibration Procedure
You do not need to design anything in CAD. Bambu Studio’s primitive tools are perfect for this.
1- Drop a cube primitive onto the build plate.
2- Scale it to 100 mm long × 10 mm wide × 5 mm high. (A longer test piece reduces the relative impact of measurement error.)
3- Select the filament you want to calibrate and make sure the Shrinkage value is still at the default 100%.
4- Slice and print the part using the exact same process profile you normally use for that material.
5- Let the part cool completely to room temperature. Do not measure it while it is still warm.
6- Measure the 100 mm length with a digital caliper. A ruler is not accurate enough for this work.
Calculating and Setting the Factor
The formula is straightforward and matches Bambu Lab’s official recommendation:
Shrinkage Compensation (%) = (Measured Size ÷ Designed Size) × 100%
Example: My Overture PLA came out at 99.75 mm.
99.75 ÷ 100 = 0.9975 → 99.75%
Go to the filament settings in Bambu Studio:
- Click the three dots next to the filament → Edit
- Filament Settings → Basic Information → Shrinkage
- Enter the value you calculated (e.g., 99.75)
- Save the profile (ideally under a clear name such as “Overture PLA – Calibrated”)
The next time you slice a model with that filament, Bambu Studio will automatically scale the X and Y dimensions so that after cooling the part matches the CAD size much more closely.
What to Expect
Reprint the same 100 mm test bar. You will usually land within a few tenths of a millimeter of the target. Perfect 100.00 mm is rare because neither the printer nor the filament is perfect, but the improvement is dramatic—especially on large parts. On an H2-series machine with a big build volume, a 0.25% error on a 400 mm part is already a full millimeter of mismatch. That is enough to ruin alignment of holes, screw patterns, or mating faces.
Important Notes and Best Practices
Shrinkage compensation primarily affects external X/Y dimensions. Internal features (holes, slots, press-fits) are better handled with the separate X-Y Hole Compensation and X-Y Contour Compensation settings under Process → Quality → Precision.
Always measure after the part has fully cooled. Measuring a warm part will give you an incorrect (too large) reading.
Dry filament consistently. Moisture changes the effective shrinkage behavior.
For higher precision, print a longer test piece (150–200 mm) or use one of the community shrinkage calibration models available on MakerWorld. Multiple measurement points reduce error.
Recheck the mechanical accuracy of your printer as well. On the H2 series, the optical calibration plate is excellent for verifying axis travel.
Typical Starting Values (for reference only)
These are community averages; always measure your own:
- Most PLA / PLA-CF: 99.70 – 99.80%
- PETG: 99.60 – 99.80%
- ASA / ABS: 99.20 – 99.50%
- PC / Nylon: often lower still
Your results will vary with brand, color, drying state, and print temperatures.
Conclusion
Material shrinkage calibration takes only a few minutes of print time and a couple of measurements, yet it is one of the highest-impact adjustments you can make for functional and large-format parts. Do it once for every material and supplier you use regularly. Combine it with proper flow, pressure advance, and the printer’s built-in mechanical calibrations, and your parts will start fitting together the way they were designed.
Happy accurate printing!
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