Toolpath viewer
G-code Simulator and Toolpath Viewer
Paste a program to see the toolpath drawn and get a machining-time estimate before you run it at the machine. It reads standard milling and turning G-code, including tool changes, peck drilling and dwells. Everything runs in your browser: nothing is uploaded to a server.
This simulator is UltraNC, a free real-time G-code viewer and machining-time simulator by the UltraNC team, embedded here with their permission. It runs entirely in your browser and never uploads your files. See ultranc.com and the MIT-licensed embed project. We do not build the viewer; we point you to the best free one and credit it plainly, the same way we cite every formula and data source on the calculators.
How to use it
Paste or drop a G-code file into the viewer above. It backplots the toolpath so you can eyeball rapids, plunges and the overall shape, and reports an estimated cycle time. Use it as a quick sanity check before posting to the machine, not as a substitute for a dry run: the time estimate is a model, and it does not simulate your specific control, lookahead or acceleration limits.
To work out the numbers that go into the program, use the feeds and speeds calculator for spindle speed and feed, and the tapping feed calculator for tapped holes. These calculators are for planning and as a starting point. Recommended speeds and feeds are published starting values that vary with your specific tool, coating, machine rigidity, workholding and coolant. Always start conservative, listen to the cut, and follow your tool maker data sheet.