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🔧 Troubleshooting February 5, 2026 4 min read

Over-Extrusion in 3D Printing: Causes and Solution Guide

Is your print looking bloated or corners rounded? 5 main causes of over-extrusion and their solutions. Detailed guide from flow calibration to E-step adjustment, temperature optimization, and slicer settings.

Quick Solution (TL;DR)

Over-extrusion is usually caused by high flow rate, high temperature, or incorrect E-step. First step: reduce the flow rate to 95%. If it doesn't fix it, lower the temperature by 5°C.

What is Over-Extrusion?

Over-extrusion is when the printer extrudes more filament than it should. The result: bloated walls, poor dimensional accuracy, blobs, and excess material between layers.

Symptoms

  • Walls are thicker than they should be
  • Corners are rounded (not sharp)
  • Small bumps/blobs on the surface
  • Excess material overflowing between layers
  • Parts don't fit into assembly holes (dimensions are too large)
  • First layer is spread out like an "elephant's foot"

5 Main Causes and Their Solutions

1. 📊 High Flow Rate

Most common cause. The slicer's flow rate value is above 100% or not adjusted for the filament.

Flow Calibration Test:

  1. Download a single-wall calibration cube (20x20x20mm, single wall)
  2. Print with flow rate at 100% and nozzle at 0.4mm
  3. Measure the wall thickness at 3 points with digital calipers
  4. If the average is 0.44mm: New flow = 100 × (0.4/0.44) = 90.9%
  5. Test again with the new value

Slicer Settings:

  • Cura: Material → Flow: 95% (general starting point)
  • PrusaSlicer: Print Settings → Advanced → Extrusion multiplier: 0.95
  • OrcaSlicer: Quality → Flow ratio: 0.95

Filament-Based Recommendations:

Filament Recommended Flow
PLA 95%-100%
PETG 93%-97%
ABS 95%-100%
TPU 100%-105%

2. 🌡️ Excessive Nozzle Temperature

Too high a temperature makes the filament overly fluid. Uncontrollable flow occurs.

Solution Steps:

  1. Reduce the temperature by 5°C
  2. Perform a temperature tower test
  3. Use the lower-middle range of the filament manufacturer's recommended range
  4. If ambient temperature is high in summer, reduce nozzle temperature by 5°C

3. ⚙️ Incorrect E-step Calibration

If the E-step value is too high, the motor pushes out too much filament.

Check and Solution:

  1. In the terminal, enter M503 command → Read the E value
  2. Perform a 100mm calibration test (method from the Under-extrusion article)
  3. If the measurement exceeds 100mm, reduce the E-step
  4. New value = Current × (100 / Actual measurement)

4. 📏 Incorrect Filament Diameter

If the filament diameter is entered in the slicer as smaller than its actual value, the printer calculates too much filament.

Solution:

  1. Measure the filament at 3 different points with digital calipers
  2. Enter the average into the slicer (usually between 1.73-1.76mm)
  3. Cheap filaments can have significant diameter variations — use a quality brand

5. 🔩 Nozzle Too Close to the Bed (First Layer)

Over-extrusion on the first layer is usually a Z-offset issue, not flow.

Solution Steps:

  1. Increase Z-offset by 0.02mm to move the nozzle further from the bed
  2. Control the first layer with a separate flow rate
  3. Cura: Initial Layer Flow: 90%-95%
  4. PrusaSlicer: First layer extrusion width: 100% (instead of auto)
  5. Perform the paper test: An A4 paper should pass with slight friction under the nozzle

Quick Diagnosis Flowchart

  1. Is flow rate above 100%? → Yes → Reduce to 95%
  2. Is temperature at the upper limit of the recommended range? → Yes → Reduce by 5°C
  3. Is E-step calibrated? → Check → Perform 100mm test
  4. Is it only on the first layer? → Yes → Adjust Z-offset
  5. Is filament diameter correct? → Measure and check

Prevention Tips

✅ Perform flow calibration test for every new filament roll ✅ Determine optimal temperature with a temperature tower ✅ For parts where dimensional accuracy is important, start with 95% flow ✅ Check dimensional accuracy by printing a calibration cube

Frequently Asked Questions

Q: Can over and under extrusion happen in the same print? Yes! In case of partial nozzle clogs, some layers might show over-extrusion and others under-extrusion.

Q: Why does PETG always seem to over-extrude? PETG is inherently more "fluid". Set the flow rate to 93%-97% and keep the temperature towards the lower end of the range.

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