How the calculators work

Every calculator on this site comes with assumptions baked in. This page documents what those are, where the numbers come from, and how often each page is reviewed. The goal is transparency: you should be able to see why the calculator says what it says, and disagree with the defaults if your situation is different.

1. Filament Cost Calculator

cost = (grams / 1000) × price_per_kg × (1 + waste_factor)

Three inputs, one formula. The waste factor defaults are based on community-aggregated data from Reddit (r/3Dprinting, r/BambuLab, r/PrusaSlicer), Bambu Lab forums, and the Klipper Discord. Defaults: PLA 5%, PETG 7%, TPU 8%, ABS 10%, Nylon 12%. These represent typical waste on a clean printer running standard settings, not edge cases.

Currency conversion is not handled by this calculator. Enter your spool price in your local currency and the math is the same. The "USD" / "EUR" toggle is cosmetic only.

2. Print Time Estimator

hours = grams / throughput_g_per_hr

Throughput numbers per printer come from community print logs posted on Reddit, Bambu Lab community forums, and the Klipper Discord, plus manufacturer specifications where available. The calculator uses typical PLA throughput at standard quality settings. Faster speeds reduce time linearly, finer detail (smaller layer heights) increases it.

This estimate is intentionally rough. For accurate per-file times, use your slicer's built-in estimate, which simulates every move at your configured speeds.

3. Electricity Cost Calculator

cost = (watts / 1000) × hours × rate_per_kWh

Average watt numbers per printer come from manufacturer specs and community Kill-A-Watt measurements. Numbers represent average power draw across a complete print, including bed heating cycles, not peak draw. Regional electricity rates are checked annually against EIA (US Energy Information Administration) data and Eurostat for European rates.

Bed heating dominates power draw in any printer, but PID controllers cycle the bed heater on and off, so average draw stays well below peak. A printer rated 350W peak typically averages 110 to 130W during a print.

4. Failure Rate Calculator

failure_rate = failed_prints / total_prints

attempts_needed = 1 / (1 - failure_rate)

The benchmark bands (under 5% excellent, 5-10% typical, 10-20% investigate, 20%+ serious issue) come from informal community surveys and conversations with print farm operators. They are not standards, just rough guideposts.

The "attempts needed" number is the geometric expectation: if 10% of attempts fail independently, on average you need 1 / 0.9 = 1.11 attempts per success. This is a simplification (real-world failures cluster, not all are independent), but it gives a useful upper bound on amortized cost.

5. AMS Purge Waste Calculator

purge_waste = swaps × purge_per_swap × flush_multiplier

Default purge values (8 g for Bambu AMS, 20 g for Prusa MMU, etc.) come from the slicer's default flush settings as of early 2026. Bambu Studio shows the actual flushed grams in the slicer's preview panel; that's the most accurate number for any specific print. The flush multiplier is adjustable in slicer settings between 0.4x and 1.5x.

6. Material Comparison

Material specifications come from manufacturer datasheets (Polymaker, Prusament, Bambu Lab, eSun) cross-referenced with community testing on Reddit and YouTube (CNC Kitchen, Stefan Hermann's tensile testing series). Where datasheets and real-world tests disagree, the calculator favors real-world numbers since marketing values are often optimistic.

Heat resistance numbers reflect deflection temperature under light load (HDT 0.45 MPa), not glass transition. This is more relevant for hobbyist use cases (does the part hold its shape in a warm car?).

Source data summary

• Manufacturer documentation: Bambu Lab wiki, Prusa knowledge base, Polymaker datasheets
• Community forums: Reddit r/3Dprinting, r/BambuLab, r/PrusaSlicer, r/FixMyPrint
• Regional electricity rates: US EIA residential rate data, Eurostat household electricity prices
• Tensile and impact data: CNC Kitchen YouTube test series, Stefan Hermann published results
• Print throughput: community-posted print logs, Klipper Discord performance threads

Update policy

Each calculator is reviewed at least once per quarter to:

• Update default prices when filament market shifts (Black Friday, supply changes)
• Add new printers as they reach hobbyist relevance
• Refresh regional electricity rate defaults
• Incorporate any reader corrections submitted via the contact page

Major calculator changes (formula changes, default value shifts larger than ~10%) get a note in the relevant page's "How this works" section. Minor corrections (typos, wording) are made silently.

Limitations and what this site does not do

• The calculators are not certified by any standards body. They are practical estimates based on community data, suitable for hobbyist use. For production work, use your slicer plus actual measurement.
• No data leaves your browser. The calculations run entirely client-side in JavaScript. URLs include your inputs so you can bookmark or share, but nothing is sent to a server.
• Pricing data is reviewed quarterly but inevitably lags the market. If you see a default that's off by more than 20%, let us know via the contact page.

Corrections and feedback

If you spot a wrong default, a stale price, or a calculation that doesn't match your printer's real behavior, please write in via the contact page. Feedback gets reviewed within a week and integrated into the next quarterly update.