PLA vs PETG vs ABS: what a print really costs in each material
The three everyday filaments sit within a few dollars of each other per spool, so it is tempting to call them equal. They are not — because you do not buy volume, you buy weight, and the three materials pack very different amounts of plastic into a kilo.
Start with the sticker price
Standard 1 kg spools of all three materials commonly sell in a similar band — roughly $15 to $25 depending on brand, color and where you shop, with the three often within a couple of dollars of each other. Specialty colors, filled variants and premium brands cost more in every material. Let's hold the comparison fair by using $20 per kilogram for all three and see what else moves the real cost. As it turns out: almost everything else.
Density: the same grams are not the same length
Filament is sold by weight but laid down by length and volume. Density is the exchange rate between the two, and it differs by material:
| Material | Density | Weight per meter (1.75 mm) | Length in 1 kg |
|---|---|---|---|
| PLA | ≈ 1.24 g/cm³ | ≈ 2.98 g | ≈ 335 m (1,100 ft) |
| PETG | ≈ 1.27 g/cm³ | ≈ 3.05 g | ≈ 327 m (1,075 ft) |
| ABS | ≈ 1.05 g/cm³ | ≈ 2.53 g | ≈ 396 m (1,300 ft) |
Read that last column again: a kilo of ABS stretches about 18% further than a kilo of PLA. Run the comparison the other way — by part instead of by spool — and it shows up in grams. A solid part with a volume of 100 cm³ weighs about 124 g in PLA, 127 g in PETG and only 105 g in ABS. At the same $20 per kilo, that part costs roughly $2.48 in PLA, $2.54 in PETG and $2.10 in ABS. Real parts are mostly infill and air rather than solid plastic, which shrinks the gap, but the direction never changes: for the same shape with the same settings, ABS is the cheapest of the three per finished part at equal spool prices, and PETG the priciest.
Failure-rate waste: the cost nobody slices
Slicers price the successful print. Your spool pays for the failures too — the warped corner that lifted at hour three, the PETG blob that took the part with it, the support that fused solid. The honest way to compare is effective cost per good print:
As an illustration with made-up-but-plausible rates: if 1 in 20 of your PLA prints fails (5%) and 1 in 7 of your ABS prints fails on an open-frame printer (~15%), a $20 kilo behaves like $21.05 of PLA but $23.53 of ABS. That single effect can erase ABS's density advantage entirely. Your rates will differ — PETG stringing and reprints are the classic quiet cost there — but the lesson is general: the material you print reliably is usually the cheapest material, whatever the spool says. Failed grams are also why tracking what a spool actually produced, rather than what it was supposed to produce, gives a truer picture of your costs.
Storage and spoilage
All three filaments absorb moisture from the air, and wet filament prints badly — popping, stringing, weak layers — which converts directly into failed prints and wasted grams. PETG is notably thirsty; PLA absorbs more slowly but is not immune; ABS sits in between. The defenses are cheap (a sealed box, desiccant, the occasional dry cycle) but the failure mode is not: a kilo left out for months in a humid room can become a kilo of stringy, brittle regret. Spoilage is a real per-material cost that never appears on a price tag, and it punishes the "buy ten colors at once" habit in every material.
Color, finish and brand premiums
Within any one material, the sticker price is not flat either. Silk, matte, wood-look and other specialty finishes in PLA commonly carry a premium of several dollars per kilo over the same brand's basic colors, and big-name brands charge more than budget labels for what is often very similar plastic. None of that changes the density math — a gram is a gram — but it changes the dollars-per-gram you should use when pricing a print. The honest approach is to cost each spool at what you actually paid for it, which is why the calculator on this site asks for each spool's own price rather than assuming one.
TPU deserves a footnote: it is usually the priciest of the common materials per kilo and the slowest to print, so its cost per finished part runs higher still — but it does jobs (flexible, grippy, impact-absorbing parts) that none of the big three can do at any price. Cost comparisons only make sense between materials that can actually do the job.
The bottom line
Per finished part at equal spool prices: ABS is cheapest on paper thanks to its low density, PLA is close behind, PETG a little dearer. Count reliability and the order flips for most home printers — PLA's low failure rate makes it the cheapest material per successful print for many people, PETG earns its small premium in toughness and temperature resistance, and ABS pays off where its strength and heat resistance are actually needed and the printer setup keeps failures rare. Choose the material for the job, then control the costs you can actually control: failures, storage, and knowing what is left on each spool. The Filament Calculator handles that last one — weigh a spool and it works out the remaining grams, meters and dollar value in whichever material you select, including a custom density if your manufacturer publishes one.