Bridging Distance Calculator
Bridging prints an unsupported horizontal strand across a gap, and whether it stays flat or droops depends on cooling, speed, temperature, and material. There is no universal maximum span, so this calculator uses the maximum you measured in your own bridge test and checks a planned span against it, flagging spans that exceed your limit and reporting the margin. It also computes the bridge traverse time, which is the span divided by your bridge print speed. Keep your tested maximum updated whenever you change material or cooling, since it is the only reliable basis for the check.
Bridging formula
Margin = tested maximum - planned span
Span percent = planned span / tested maximum * 100
Traverse time = planned span / bridge speed
Status = within limit if margin is at least zero
The traverse time is exact geometry. The maximum span is your measured calibration value, never an assumed number, so the check reflects your own machine.
Bridging context
- Maximum bridge span is calibrated per machine, material, and cooling; it is not universal.
- Find your maximum with a bridge test model that steps up the span.
- Use a dedicated, slower bridge speed with full cooling for clean strands.
- More cooling, lower speed, and lower temperature usually extend the safe span.
- Re-test and update the maximum after any material or fan change.
Bridging: frequently asked questions
What is bridging in 3D printing?
Bridging is printing a horizontal line of plastic across a gap with no support beneath it. The molten strand spans from one wall to another and must cool fast enough to stay taut. How far it can span before sagging is a calibrated property of your printer, fan, and material.
What is the maximum bridge distance?
There is no universal figure; the safe span depends on cooling, speed, temperature, and material, so this calculator treats your maximum as a user-supplied value from your own bridge test. Enter the longest clean bridge you have achieved, and the tool flags spans that exceed it.
How do I find my maximum bridge span?
Print a bridge test model with progressively longer unsupported spans and inspect which ones stay flat. The longest span that prints without drooping is your practical maximum for that material and cooling setup.
How long does a bridge take to print?
The traverse time is the bridge length divided by the bridge print speed. Many slicers use a slower, dedicated bridge speed with full cooling to help the strand set, so enter that speed rather than your normal print speed.
How can I bridge farther?
Increase part cooling, lower the bridge speed slightly so each strand has time to set, reduce the nozzle temperature within the workable range, and ensure the bridge anchors are solid. Re-run the bridge test after any change to update your maximum.
Official sources
- RepRap project documentation: reprap.org (bridging and cooling reference).
- Marlin firmware documentation: Configuration reference.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.