ABC Tools

3D Print Cost & Time Calculator, Explained

After reading this you can estimate what a 3D print really costs, from filament and electricity to a failure surcharge and a selling price, and you will know which inputs matter and which ones lie to you.

What this calculator does

A finished print looks like a small pile of plastic, but the true cost has four layers: the filament you consumed, the electricity you burned, the fraction of prints that failed, and any markup if you sell the part. This tool adds those layers into one number and, optionally, a suggested price.

Here is the hook. Suppose you print a 100 gram PLA bracket. The filament costs about 22 currency units per kilogram, so the plastic alone is 2.20. That is the number most people quote. But add 10% waste for the brim and purge, another 5% for prints that fail, roughly 0.55 of electricity for a five hour job, and the real cost lands near 3.15. That is 43% more than the naive figure. The gap is where hobby pricing goes wrong.

When to use it, and when not

Use it when you want a defensible cost for a part you will sell, quote, or compare against buying the item outright. It is also good for deciding whether a design change (dropping infill from 40% to 20%, say) is worth the fiddling.

Do not use it as a slicer. The slicer knows your exact wall count, top and bottom layers, support volume, and travel moves. If you have already sliced the model, take the grams and the time straight from the slicer and enter those. The volume route in this tool is a heuristic for the early stage, before you have a sliced file.

If your slicer reports both weight and print time, feed the weight in and treat this tool as an electricity and pricing layer on top. That is the most accurate path by a wide margin.

The cost formula, built up piece by piece

Start with the material mass. If you know the weight in grams, use it directly. If you only have a solid model volume from CAD, you must estimate how much of that volume is actually plastic, because the inside is mostly air.

m_{\text{solid}} = V \cdot \rho

Here V is the model volume in cm³ and \rho is the filament density in g/cm³ (PLA is 1.24, PETG 1.27, ABS 1.04). A fully solid 100 cm³ PLA block would weigh 124 g.

But you rarely print solid. The shell (walls plus top and bottom) is dense, and the interior is a sparse lattice. This tool uses a simple split: about 25% of the volume behaves as solid shell, and the remaining 75% scales with your infill percentage.

f_{\text{fill}} = 0.25 + 0.75 \cdot \dfrac{i}{100}

i is the infill percentage. At 20% infill, f_{\text{fill}} = 0.25 + 0.75 \cdot 0.20 = 0.40. So a 100 cm³ model uses about 40% of its solid mass.

Now add waste (brims, supports, purge, and failed first layers) and put it together. The filament mass for one good attempt is:

m = V \cdot \rho \cdot f_{\text{fill}} \cdot \left(1 + \dfrac{w}{100}\right)

w is the waste percentage. Multiply by price per kilogram divided by 1000 to get the filament cost in currency.

Time and electricity

Print time comes from a throughput rate in grams per hour, which depends on the material and the speed class. Standard PLA runs near 15 g/h on a typical bedslinger. Draft (thicker layers) is about 1.6 times faster; quality (thin layers) is about 0.6 times as fast.

t = \dfrac{m}{R}

R is the throughput in g/h. Electricity is then the average power draw times the time:

C_{\text{energy}} = \dfrac{P}{1000} \cdot t \cdot p_{\text{kWh}}

P is the average wattage (not the peak, because the bed heater cycles on and off), and p_{\text{kWh}} is your electricity price. Use the average, typically 100 to 150 W for PLA, or the energy figure will be roughly double reality.

The failure surcharge

Some prints fail. If a share F of your attempts end in the bin, the good prints have to carry that lost cost. Divide the base cost by one minus the failure fraction:

C_{\text{adj}} = \dfrac{C_{\text{base}}}{1 - F/100}

At 5%, the divisor is 1 - 0.05 = 0.95, so the cost rises by a factor of 1/0.95 \approx 1.0526, about 5.3%. The intuition: one in twenty prints is wasted, so each of the nineteen survivors carries an extra 1/19 of a print.

The surcharge blows up as failure approaches 100%. At 50% failure the cost doubles; at 90% it multiplies by ten. If your failure rate is really that high, fix the printer before you price anything.

A worked example with the demo data

PLA bracket, volume route, 20% infill

These are the exact demo values: PLA at 22 per kg, volume mode, 100 cm³, 20% infill, 10% waste, standard speed, 120 W, 0.25 per kWh, 5% failure, 0% markup.

  1. Solid mass: 100 \cdot 1.24 = 124 g.
  2. Fill factor: 0.25 + 0.75 \cdot 0.20 = 0.40.
  3. Filled mass: 124 \cdot 0.40 = 49.6 g.
  4. With 10% waste: 49.6 \cdot 1.10 = 54.56 g.
  5. Filament cost: 54.56 \cdot 22 / 1000 = 1.200.
  6. Print time at 15 g/h: 54.56 / 15 = 3.637 h.
  7. Energy: (120/1000) \cdot 3.637 \cdot 0.25 = 0.1091.
  8. Base cost: 1.200 + 0.1091 = 1.309.
  9. Failure adjusted: 1.309 / 0.95 = 1.378.
  10. With 0% markup, the suggested price equals the cost: about 1.38.

So a 100 cm³ part at 20% infill costs roughly 1.38, and the plastic itself is 1.20 of that. Electricity is small here (about 8 cents) because PLA prints fast and the bed is not very hot.

Reading and interpreting the result

The single most useful thing to notice is the split between filament and everything else. For a fast PLA print the plastic dominates and electricity is a rounding error. For a slow, hot, 20 hour ABS print with an enclosure, electricity can rival the filament cost, because time went up and power went up together.

Infill has a strong, nonlinear feel because of the shell floor. Going from 0% to 20% infill only lifts the fill factor from 0.25 to 0.40, because the shell is always there. Going from 20% to 100% takes it from 0.40 all the way to 1.00. The chart below shows filament cost against infill for the demo part.

Cost rises linearly with infill, but it starts at 0.68 (not zero) because the 25% shell is always printed. The marker sits at the demo value of 20%.

With the demo values, cost splits into filament 1.20, electricity 0.11, and a failure surcharge of about 0.07, for a total near 1.38. Raising infill or slowing the print raises the filament and electricity slices; raising the failure rate inflates the surcharge sharply above 50%.

Common mistakes

The volume route is the biggest source of error. CAD reports the solid volume, but the tool cannot know your wall count or how many top and bottom layers you set. A phone stand with thick walls and a solid base can use far more plastic than the 25% shell assumption. When accuracy matters, slice the model and enter grams.

The second mistake is entering peak power. A printer might pull 300 W the instant the bed heater kicks on, but it does not hold that. The bed cycles, and once up to temperature the average for a PLA job is often 100 to 150 W. Use the average or your energy cost roughly doubles.

The third mistake is trusting the throughput rate blindly. Fifteen grams per hour is a typical bedslinger number, but a fast CoreXL machine or a heavily tuned profile can do double that, and a big detailed print at 0.1 mm layers can crawl below half. Calibrate once: time a real print, divide its grams by its hours, and use that rate.

Densities differ by material, so weight for the same volume changes. The same 100 cm³ solid is 124 g in PLA, 127 g in PETG, but only 104 g in ABS. If you switch materials, do not reuse the old gram figure.

Related tools

3D printing usually sits inside a larger build. If your project also involves cutting stock, the Cut List Optimizer packs parts onto the fewest boards or bars, and the Sheet Goods Cut Optimizer nests rectangles on plywood. For machined parts rather than printed ones, the CNC Feeds & Speeds Calculator gives spindle RPM and feed rate. For carpentry, see the Roof Pitch & Rafter Calculator and the Stair Calculator.

Frequently asked questions

Why is my slicer weight different from the volume estimate?

The slicer knows exact wall count, top and bottom layers, support volume, and travel purge. The volume route assumes a flat 25% shell plus 75% scaled by infill. For a thin-walled model the shell assumption overshoots; for a thick, chunky part it can undershoot. Enter the slicer grams when you have them.

Should I include the printer purchase and wear in the cost?

This tool does not, and for a hobby it is usually fine to skip it. If you print commercially, add a per-hour machine rate on top of the result: divide the printer price plus expected maintenance by its lifetime hours, then multiply by the print time. A 500 machine over 3000 hours adds about 0.17 per hour.

What failure rate should I enter?

Use your honest long-run share of failed prints, not a single bad week. A well-tuned printer running proven profiles sits around 2 to 5%. If you are printing tricky overhangs in TPU or bridging large gaps, 10 to 20% is realistic. Remember the surcharge grows fast above 50%.

How do I set the markup for selling?

Markup is a percentage added to the adjusted cost. At 0% the price equals the cost. At 100% it doubles. A common workshop figure is 50 to 200% to cover your time, design work, and packaging, none of which this tool prices for you.

Does layer height change the cost or just the time?

Mostly the time. A 0.12 mm quality print uses about the same plastic as a 0.2 mm standard print of the same model, but it takes far longer, so electricity rises. The speed class captures this: quality runs at about 0.6 times the standard throughput.

Try it yourself in the tool

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