Injection Molding Cost Guide
Injection molding cost: tooling, piece price, and the crossover.
Molding has two prices — a one-time tool and a tiny per-shot cost. This guide puts typical numbers on both, and shows the quantities where molding actually starts beating CNC machining.
Molding is two prices, not one
Every injection molding quote splits into a one-time tooling charge and a per-part shot price. Which one dominates depends entirely on quantity — and that single fact decides whether molding is the right process at all.
$1,500–30,000
One-time: the tool
Every molded part starts with a machined aluminum or steel tool. Part size, cavity count, and finish set the price — and a design change after cutting steel costs thousands.
$0.50–5
Per part: the shot
Once the tool exists, each part is resin plus seconds of press time. This is why molded piece prices embarrass every other process — at volume.
~250 units
The crossover
Total cost = tooling + quantity × shot price. Below the crossover there is no tooling to amortize, so CNC machining — no tool, no design freeze — usually wins.
Four routes to molded parts
“I need plastic parts” has four practical answers, and they are not interchangeable — each pairs a tooling bill with a piece price, a lead time, and a tool life. CNC machining is on the list because below a few hundred units it beats all three molding routes on total cost.
| Route | Tooling | Per part | First parts | Tool life | Best for |
|---|---|---|---|---|---|
| CNC machining | No tooling | ~$12–85 | from 7 days | — | Functional parts from 1 to ~500 units in production plastics or metal. The design stays changeable — every revision costs nothing but the parts. |
| Urethane casting | ~$400–900 / mold set | ~$35–60 | from 10 days | ~20 casts per mold | Runs of 5–50 in elastomers (Shore A 30–90), optically clear resins, or overmolds — and complex cosmetic geometry: silicone molds do not care about undercuts, thin walls, or texture. Not a price play for simple rigid parts. |
| Injection molding — rapid aluminum tooling | ~$1,500–5,000 | ~$1–5 | from 14 days | 5,000–10,000 shots | A few hundred to ~10,000 parts in the final molded resin. The bridge between machined prototypes and production steel. |
| Injection molding — production steel tooling | ~$8,000–30,000 | ~$0.50–2 | 4–8 weeks | 100,000+ shots | Volumes of 10,000 and up, once the design is frozen. Lowest piece price of any plastic process. |
Where the total-cost lines cross
Every route is a straight line: tooling up front, then a fixed price per part. Plot them and the decision reads itself off the chart — where two lines cross is the quantity where you switch process. Reference part: a palm-size ABS housing (120 × 80 × 30 mm, 2.5 mm walls).
First 1,000 units — machining vs rapid tooling
The lines cross at ≈250 units: below it CNC machining is cheaper (no tooling to pay off), above it the $2,500 aluminum tool starts earning its keep. One caveat the chart cannot show: this reference part is a machining-friendly rigid housing — urethane casting competes on geometry and materials (soft, clear, undercut — see the polymer map below), not on price for parts like this. Production steel ($12,000 before the first part) does not even fit on this chart.
To 10,000 units — rapid tooling vs production steel
Second crossover at ≈4,000 units: the steel tool’s $1.20 shot price overtakes aluminum’s $3.50. CNC exits the race early at this scale — its line leaves the chart before 3,000 units.
The same story as per-part numbers, tooling amortized in — green marks the cheapest practical route at each quantity:
| Quantity | CNC machining | Urethane casting | Rapid aluminum tool | Production steel tool | Cheapest route |
|---|---|---|---|---|---|
| 10 | ~$20/part | ~$105/part | ~$254/part | — | CNC — nothing to amortize |
| 50 | ~$15/part | ~$58/part | ~$54/part | — | CNC — tooling still dominates the others |
| 200 | ~$14/part | ~$50/part | ~$16/part | ~$61/part | CNC — last cheap stop before the ~250-unit crossover |
| 1,000 | ~$13.50/part | — | ~$6/part | ~$13/part | Rapid tooling pays off |
| 10,000 | ~$13.50/part | — | ~$3.75/part | ~$2.40/part | Steel tooling — piece price wins |
Read the green column top to bottom and the strategy writes itself: machine the first few hundred units while the design is still moving, cut a rapid aluminum tool when a stable design needs four figures of parts, and commit to steel only at real volume. That is exactly how experienced hardware teams stage a launch — see the prototype manufacturing page for the front end of that sequence.
Assumptions behind the table: CNC machined ABS at ~$60 setup + ~$13.50 per part; urethane casting at ~$400 master pattern + ~$250 per silicone mold (~20 casts each) + ~$35 per cast; rapid aluminum tool at ~$2,500 + ~$3.50 per shot; production steel tool at ~$12,000 + ~$1.20 per shot. Typical US-market program pricing for the reference geometry, rounded — not a quote. “—” means the route is impractical at that quantity (mold life or tooling economics). Your part is priced on its own geometry and confirmed by engineering review.
The polymer map: who can shape what
Price only settles the argument when more than one route can make your material at all. Machining owns the high-performance billet end, casting owns soft and clear parts at prototype quantity, and molding makes everything — at volume. Property data below comes from the FabDigit materials library.
| Material | CNC machining | Urethane casting | Injection molding | Worth knowing |
|---|---|---|---|---|
| ABS | Billet | ABS-Like PU | Native | The default prototype resin — every route can make it. |
| PC (polycarbonate) | Billet | PC-Like PU | Native | Impact-resistant housings and lenses; molded PC needs pre-dried resin. |
| PA66 (nylon) | Billet | Nylon-Like PU | Native | Strongest of the commodity set — machines and molds equally well. |
| POM (acetal) | Native — billet | — | Native | The machining plastic: gears, bearing fits, sliders. No cast mimic exists — machine it below tooling volume. |
| PP (polypropylene) | Soft billet | PP-Like PU | Native | Living hinges exist only molded — no billet or cast route makes them. |
| PMMA (acrylic) | Billet + polish | Rigid Clear PU | Optical tooling | The clear-parts ladder: machine 1–5, cast 5–50, mold at volume. |
| PEEK | Native — billet | — | Volume only | High-performance parts stay machined until real volume — molding PEEK needs hardened high-temp tooling. |
| Rigid PU (cast) | — | Native — 5–50 parts | — | The casting workhorse: mimics ABS/PC without a metal tool, molded-in finish. |
| TPU (Shore A 90) | — | Shore A 30–90 | At volume | Elastomers lock machining out — casting is the no-tooling route to rubber parts. |
| Silicone | — | Shore A 20–70 | LSR (specialty) | Seals, gaskets, skin-contact parts at prototype quantity. |
Same ten polymers — raw-material cost, strength, and how they behave under a cutter:
| Material | Material cost | Tensile strength | Hardness | Machinability |
|---|---|---|---|---|
| ABS | $ | 40 MPa | 105 HRR | Excellent |
| PC (polycarbonate) | $ | 70 MPa | 118 HRR | Better |
| PA66 (nylon) | $$ | 95 MPa | 115 HRR | Better |
| POM (acetal) | $$ | 70 MPa | 115 HRR | Excellent |
| PP (polypropylene) | $ | 35 MPa | 90 HRR | Better |
| PMMA (acrylic) | $ | 75 MPa | 95 HRM | Better |
| PEEK | $$$$$ | 110 MPa | 99 HRM | Better |
| Rigid PU (cast) | $ | 58 MPa | Shore D 80 | not machined |
| TPU (Shore A 90) | $$ | 15 MPa | Shore A 90 | Poor |
| Silicone | $$ | 8 MPa | Shore A 20–70 | not machined |
Read the two tables together and the casting question answers itself: the last three rows — cast PU, TPU, silicone — are where machining shows a dash and casting shows green. That is why urethane casting is everywhere in prototyping despite losing the price chart above: it is the only no-tooling route to soft, clear, and complex cosmetic parts. Full datasheets and per-process availability live in the materials library.
Cost bars are relative raw-material cost per kg (PEEK = 100); strength bars are tensile strength scaled to PEEK’s 110 MPa. Hardness values use each family’s native scale (Rockwell R/M for rigid plastics, Shore A/D for elastomers and cast resins), so compare within a row’s family, not across scales. Values from the FabDigit materials library,September 2026.
What drives tooling price
Two housings the same size can quote $2,000 apart in tooling. These six factors are almost always why — and four of them are design choices you control before uploading CAD.
- Part size sets tool size. A bigger part needs a bigger mold base and more machining — tooling price scales with projected area faster than with part complexity.
- Cavity count multiplies cost and divides piece price. A 4-cavity tool costs roughly 2–3× a single cavity but cuts the shot price per part — only worth it at tens of thousands of units.
- Aluminum vs hardened steel. Aluminum cuts fast and cheap but lasts ~5,000–10,000 shots. Hardened steel costs 3–6× more and runs into the millions.
- Undercuts need side actions. Every slide or lifter adds roughly $1,000–3,000. A snap-fit redesigned to pull straight from the tool is the cheapest DFM win in molding.
- Surface finish is machining time. Mirror polish and EDM textures are hand-finished hours. Take the standard SPI finish on internal and hidden faces.
- Glass-filled resins eat tools. Abrasive fills force hardened steel even at modest volumes — a material choice made in CAD that shows up in the tooling quote.
Injection molding cost — FAQ
How much does injection molding cost?
Two numbers: the tool and the shot. Rapid aluminum tooling for a palm-size part typically runs $1,500–5,000 and production steel $8,000–30,000, while the molded part itself is usually $0.50–5 in resin and press time. Amortized together, molding beats CNC machining only once quantity climbs into the hundreds.
When does injection molding become cheaper than CNC machining?
For a typical palm-size ABS housing the total-cost lines cross at about 250 units (200–500 depending on geometry). Below that, machining wins because there is no tooling to amortize and the design stays changeable. Above it, rapid aluminum tooling takes over, and production steel wins from roughly 4,000 units up.
What is urethane casting and when is it worth it?
Urethane casting pours polyurethane into silicone molds taken off a master pattern. A mold set runs about $400–900 and yields roughly 20 casts at $35–60 per part. Its real strengths are things machining cannot do at any price: Shore A 30–90 elastomers, optically clear parts, overmolds, and complex cosmetic geometry — the silicone mold does not care about undercuts or thin walls, and parts come out with a molded-in finish. For simple rigid housings it is rarely cheaper than CNC machining, which is why it lives in the 5–50 unit looks-like and soft-part niche.
What is rapid or bridge tooling?
An aluminum production tool cut in about two weeks for $1,500–5,000, good for 5,000–10,000 shots in the final resin. It bridges the gap between machined prototypes and full production steel — you get real molded parts while the design earns its freeze.
How long does tooling take?
Rapid aluminum tooling typically ships first parts in about 2 weeks. Production steel tooling runs 4–8 weeks including T1 samples and tuning. CNC machined parts, needing no tool, arrive in about 7 days — which is why programs machine while they wait.
Do I own the mold?
Yes — tooling you pay for is customer-owned. It is stored and maintained at the production facility, documented, and transferable if you ever move production.
Price both routes on your actual part.
Upload a CAD file and compare machined and molded pricing on your real geometry — engineering review included, before you commit to tooling.