How long does a 3D print take? Five parts, three layer heights

The five parts

Volumes are the plastic the slicer lays down — what your slicer reports as filament volume — not the bounding box of the model. A 120 × 80 × 60 mm enclosure has a 576 cm³ bounding box and about 170 cm³ of extruded plastic at 3 walls and 20% infill; mixing the two up is the most common reason a hand estimate is four hours out. That conversion has its own page.

The estimate, in one line

hours = volume_mm³ ÷ (layer height × line width × speed) ÷ 3600 × (1 + overhead). At 0.2 mm layers, 0.45 mm wide and 60 mm/s the machine deposits 19.44 cm³ an hour, and the 15% overhead for travel and layer changes brings the effective rate to 16.90 cm³/h. A 25 cm³ phone stand therefore takes 1.5 h.

That is faster than a real print, and the page says so rather than pretending: a real slicer inserts accelerations, retractions, travel moves and cooling pauses, which is where the ±20% tolerance comes from. Use this number to decide whether a job fits in tonight, not to promise a customer a 15:00 delivery.

Layer height is the lever with the widest range

Hours scale inversely with layer height, so going from 0.28 mm to 0.12 mm on the same model is a 2.3× change with no other settings touched: the helmet goes from 7.6 h to 17.7 h, and the vase from 1.5 h to 3.5 h. Printing a functional bracket at 0.12 mm buys nothing you can see and costs 133% more machine time.

The other multiplier nobody mentions is nozzle width. A 0.6 mm nozzle at the same speed deposits 1.33× the plastic of a 0.45 mm one, so the phone stand drops from 1.5 h to about 1.1 h — at the cost of surface quality and fine detail. Wide nozzle for structural parts, narrow for display.

What this model cannot see

• Supports and infill are already inside the extruded volume if you took the number from your slicer. If you estimated the volume yourself, add them first — supports can be 10–20% of a part like the helmet.
• Acceleration and firmware limits. A machine that never reaches 60 mm/s on short segments prints slower than this model, which is why small detailed parts surprise people more than large simple ones.
• Filament throughput. The hotend has a ceiling. On a 0.4 mm nozzle at high speed the extruder, not the motion system, becomes the limit.

Time is the product you are selling

A printer has 168 hours in a week and you have fewer than that in attention. At 20 productive hours a week you can deliver 2 helmets or 14 phone stands — and the machine earns only while it runs. That is why choosing a printer for paid work is a question about hours, not about price, and why the quote template asks for a lead time in days rather than "as soon as possible".

For the money side of the same part, see cost per gram; for the full bill including electricity and machine time, see how much 3D printing costs.

Frequently asked questions