Estimate 3D print time without opening a slicer

The slicer's estimate is the accurate one - it simulates every toolpath. But you don't always have the file sliced when the question comes up. A customer asks how long their part will take while you're answering messages on your phone. You're deciding between printing something at 0.2 mm versus 0.28 mm and want a feel for the difference before re-slicing. You're scheduling three printers' worth of weekend jobs and need rough numbers, not perfect ones.

That's the gap this estimator fills: enter approximate model weight, layer height, infill, speed, and an efficiency factor, and get a rough duration for planning. It's a heuristic, not a simulation - treat the result as a planning number and let the slicer have the final word before you promise anyone a deadline.

What actually drives print time

Four settings dominate, and knowing how they interact makes your estimates smarter:

  • Layer height is close to linear: a 0.1 mm print needs twice the layers of a 0.2 mm print, and takes roughly twice as long. It's the single biggest lever - dropping from 0.2 mm to 0.12 mm for looks nearly doubles the job.
  • Model size compounds fast, because material follows volume. Scale a part to 150% and you're printing about 3.4x the plastic (1.5^3).
  • Infill adds time proportionally to how much internal plastic it lays down. The jump from 15% to 40% costs real hours on big parts while adding less strength than people expect - walls are usually the better investment.
  • Speed helps only as far as your hotend can melt plastic. Modern fast printers are usually limited by flow rate (roughly 20 - 25 mm^3/s on standard hotends), not motion. Doubling the speed setting rarely halves the time.

Why slicer estimates beat any calculator (and still miss)

A slicer's number includes travel moves, acceleration limits, retractions, slow outer walls, supports, and your printer's actual profile - things no weight-based formula can see. That's why this tool says, right in the interface, that the slicer should be the final source before scheduling.

Even slicer estimates drift, though. Multi-color prints add flushing and tower time the preview underestimates; first layers run slow; pauses and filament swaps add real minutes. The practical workflow: use this estimator to compare scenarios and rough out schedules, use the slicer to commit, and pad customer-facing promises by 10 - 20% on top of that.