Print tools / ERS
Works offline

A calculator for OrcaSlicer

Extrusion rate
smoothing.

Calculate a starting value for your slicers Extrusion Rate Smoothing setting using line width, layer height, and acceleration.

Rounded-rectangle extrusion cross-section A line of width w and height h, formed by a rectangle and two semicircular ends. Diagram is schematic. width · w A h
ROUNDED-RECTANGLE CROSS-SECTION

Your print settings

mm
mm
mm/s²

Use the acceleration magnitude for the feature you’re tuning, typically the outer wall.

70%

Percentage of the natural maximum.
Lower percentage = stronger smoothing.

Start at 70%, then adjust with a test print. The suggested starting range is 60–80%.

Recommended starting ERS

—mm³/s²

Enter your print settings to calculate.

Copies just the number, ready for OrcaSlicer.

Natural ERS maximum
—mm³/s² · A × acceleration
Cross-sectional area
—mm² · rounded rectangle

Suggested starting range

60–80% of maximum
— mm³/s²

Your 70% setting is within the suggested range.

Use the starting value

In OrcaSlicer, open Speed → Advanced → Extrusion rate smoothing. Enter the starting ERS in mm³/s², then tune with a test print.

Lower means more smoothing

A lower ERS spreads flow changes over more time and distance, and can increase print time. The natural maximum is a reference for these settings.

No speed inputs needed

With a fixed cross-section, flow = A × speed, so flow change per second = A × acceleration. Start and end speeds change the transition duration, not this slope.

The math & assumptions

A = h × [w − (1 − π/4) × h]

ERSmax = A × a

ERSstart = ERSmax × (factor / 100)

Range = 0.60 × ERSmax to 0.80 × ERSmax

w = line width (mm), h = layer height (mm), a = acceleration magnitude (mm/s²). The rounded rectangle requires w ≥ h > 0 and a > 0.

This geometric estimate assumes constant cross-section and acceleration, with no flow-multiplier correction. It is a tuning starting point; actual behavior depends on the printer, material, and toolpath.

ERS measures change in flow (mm³/s²), distinct from maximum volumetric flow (mm³/s). Results use full precision internally; displayed ERS values are normally rounded to one decimal.