Why this is the core feeds and speeds formula
Every material-specific feed rate calculator, whether for acrylic, plywood, MDF, or anything else, ultimately runs through this same relationship underneath. Once you know the right chip load for a given material, tool, and cutting condition, feed rate is simple arithmetic rather than guesswork or trial and error at the machine.
How the number is calculated
Feed rate in inches per minute equals spindle speed in RPM multiplied by the number of flutes on the tool, multiplied by the chip load per flute. Doubling any one of those three inputs doubles the feed rate, which makes it straightforward to see how a change to spindle speed or a tool swap should shift your feed rate to keep chip load consistent.
Practical tips
Chip load recommendations come from tool manufacturers and material charts as a starting range, not a single fixed number, so treat the result here as a starting point to dial in based on how the cut actually looks and sounds. If you change tools to one with a different flute count, recalculate feed rate rather than reusing the old number, since flute count has a direct, linear effect on the correct feed rate for the same chip load.