Plastic Density Chart: g/cm³ & kg/m³ Values for All Common Plastics
Density is the single most important value for calculating plastic part weight. This reference covers density values for 20+ common thermoplastics and engineering plastics — both in g/cm³ (the standard for weight calculation) and kg/m³ (used in structural and FEA work) — with grade-level data and ASTM sources.
Using these values in a design?
Published density values are nominal figures for virgin, unfilled material at 23°C. Real parts can vary ±2–5% depending on filler content, processing conditions, and grade. Always verify against your supplier's material data sheet for safety-critical or regulated applications.
Plastic Density Chart — All Common Materials
Values are nominal at 23°C per ASTM D792 / ISO 1183 test method unless noted. Multiply g/cm³ × 1000 to convert to kg/m³.
Polyolefins (Lightest Group — Float in Water)
| Material | Density (g/cm³) | Density (kg/m³) | Standard |
|---|---|---|---|
| Polypropylene (PP) Homopolymer | 0.90–0.91 | 900–910 | ASTM D4101 |
| Polypropylene (PP) Copolymer | 0.89–0.91 | 890–910 | ASTM D4101 |
| LDPE (Low-Density Polyethylene) | 0.91–0.94 | 910–940 | ASTM D1248 |
| UHMW-PE | 0.93–0.94 | 930–940 | ASTM D4020 |
| HDPE (Natural / PE300) | 0.94–0.96 | 940–960 | ASTM D3350 |
| HDPE Pipe Grade (PE4710) | 0.955–0.960 | 955–960 | ASTM D3350 |
General-Purpose Engineering Plastics (Sink in Water)
| Material | Density (g/cm³) | Density (kg/m³) | Standard |
|---|---|---|---|
| ABS (Standard / Natural) | 1.04–1.06 | 1040–1060 | ASTM D1248 |
| ABS Flame Retardant | 1.18–1.22 | 1180–1220 | ASTM D1248 |
| ABS 20% Glass-Filled | 1.19–1.22 | 1190–1220 | ASTM D1248 |
| Acrylic / PMMA (Cast) | 1.17–1.20 | 1170–1200 | ASTM D4802 |
| Acrylic / PMMA (Extruded) | 1.18–1.19 | 1180–1190 | ASTM D4802 |
| PVC (Rigid / Type 1) | 1.38–1.40 | 1380–1400 | ASTM D1784 |
| PVC (Type 2 / Impact Modified) | 1.35–1.38 | 1350–1380 | ASTM D1784 |
| Polycarbonate (PC) Standard | 1.19–1.22 | 1190–1220 | ASTM D3935 |
| Polycarbonate 30% Glass-Filled | 1.40–1.43 | 1400–1430 | ASTM D3935 |
High-Performance Engineering Plastics
| Material | Density (g/cm³) | Density (kg/m³) | Standard |
|---|---|---|---|
| Nylon 6 (PA6) | 1.12–1.14 | 1120–1140 | ASTM D4066 |
| Nylon 6/6 (PA66) | 1.13–1.15 | 1130–1150 | ASTM D4066 |
| Nylon 6/6 30% Glass-Filled | 1.37–1.40 | 1370–1400 | ASTM D4066 |
| POM-H (Delrin / Acetal Homopolymer) | 1.41–1.43 | 1410–1430 | ASTM D6100 |
| POM-C (Acetal Copolymer) | 1.39–1.42 | 1390–1420 | ASTM D6100 |
| Polyurethane (Cast PU, Shore 60A) | 1.10–1.14 | 1100–1140 | ASTM D792 |
| Polyurethane (Cast PU, Shore 90A–75D) | 1.18–1.25 | 1180–1250 | ASTM D792 |
| PEEK (Unfilled) | 1.30–1.32 | 1300–1320 | ASTM D792 |
| PEEK 30% Glass-Filled | 1.49–1.51 | 1490–1510 | ASTM D792 |
| PTFE (Virgin) | 2.14–2.20 | 2140–2200 | ASTM D1457 |
| PTFE 25% Glass-Filled | 2.28–2.32 | 2280–2320 | ASTM D1457 |
| PTFE 15% Carbon-Filled | 2.08–2.12 | 2080–2120 | ASTM D1457 |
g/cm³ ↔ kg/m³ Conversion
The two units are related by a factor of exactly 1000:
How Plastic Density Is Measured
The standard test method for plastic density is ASTM D792 (or the equivalent ISO 1183-1), which uses the Archimedes principle: a sample is weighed in air, then weighed fully submerged in water. The density is calculated from the buoyant force difference.
This method is accurate to ±0.001 g/cm³ for most unfilled materials. Porous, foamed, or highly filled materials may require the immersion method (ASTM D792 Method B) or gas pycnometry for better accuracy.
ASTM D792 Formula
Where density of water = 0.9975 g/cm³ at 23°C (the standard test temperature).
When comparing values from different material data sheets, check whether they are measured at 23°C — some older data sheets report density at 20°C, which can differ by 0.002–0.005 g/cm³ for most thermoplastics.
How Density Is Used to Calculate Plastic Weight
Weight = Volume × Density. The formula is the same for every shape — only the volume formula changes.
Sheet
L, W, T in mm → result in grams. Divide by 1000 for kg.
Rod / Bar
D = diameter in mm, L = length in mm. ρ = density in g/cm³.
Tube / Pipe
OD = outer diameter, ID = inner diameter, both in mm.
Worked example: ABS sheet
500 mm × 500 mm × 10 mm sheet, ABS (1.05 g/cm³):
A 5% difference in density (e.g., choosing ABS at 1.05 vs flame-retardant ABS at 1.20 g/cm³) changes the calculated weight by approximately 14% — meaningful for shipping cost estimates and structural load calculations.
Factors That Change Real-World Plastic Density
Published density values are measured on standardised test specimens under controlled conditions. Actual parts can differ for several reasons:
Fillers and reinforcements
Glass fiber (density ~2.5 g/cm³) always increases density relative to the unfilled base resin. Carbon fiber (~1.8 g/cm³) may increase or decrease density depending on loading. PTFE filler (~2.16 g/cm³) increases density in softer base resins. A 30% glass-filled Nylon 6/6 is ~20% denser than unfilled Nylon 6/6 (1.14 vs 1.38 g/cm³).
Crystallinity
Semi-crystalline plastics (HDPE, PP, Nylon, POM, PEEK) have a denser crystalline phase alongside an amorphous phase. Slow cooling increases crystallinity and density; rapid quench cooling reduces both. This is why HDPE pipe grade (0.955 g/cm³) is slightly denser than natural HDPE sheet grade (0.94 g/cm³) — different thermal histories during processing.
Temperature
Most thermoplastics expand 0.05–0.15% per °C. At their upper service temperature, most plastics are 2–5% less dense than at 23°C. For PTFE (upper limit 260°C), density drops from ~2.16 g/cm³ at 23°C to approximately 2.05 g/cm³ near its service limit. For weight calculations used in shipping or ambient applications, 23°C values are appropriate.
Moisture absorption
Hygroscopic materials like Nylon absorb moisture from the environment. Nylon 6/6 can absorb up to 2.5% water by weight at 50% relative humidity, which adds measurable mass without significantly changing dimensions. Published density values are typically for dry-as-moulded (DAM) or conditioned specimens — check the data sheet conditions for Nylon applications.
Coloured and pigmented grades
Black grades often contain carbon black (density ~1.8 g/cm³), which increases density slightly over natural grades. Titanium dioxide (TiO₂) used in white grades has a density of ~4.2 g/cm³ and at 5–10% loading can meaningfully increase the density of low-density base resins like PP. For high-precision work, confirm density with the specific coloured grade data sheet.
Density Ranges by Plastic Family
When selecting materials for weight-sensitive applications, these broad groupings help narrow the field:
Lightest (<1.0 g/cm³) — Float in water
- PP Homopolymer: 0.90–0.91
- LDPE: 0.91–0.94
- UHMW-PE: 0.93–0.94
- HDPE: 0.94–0.97
Best for: buoyant components, lightweight enclosures, marine applications.
Light-Medium (1.0–1.2 g/cm³)
- ABS: 1.04–1.06
- PU (soft grades): 1.10–1.14
- Nylon 6/6: 1.13–1.15
- Acrylic / PC: 1.17–1.22
Best for: structural enclosures, machined components, optical parts.
Medium-Heavy (1.2–1.5 g/cm³)
- PEEK: 1.30–1.32
- PVC (rigid): 1.38–1.40
- POM / Delrin: 1.41–1.42
- GF-Nylon 30%: 1.37–1.40
Best for: gears, bearings, structural wear parts, chemical equipment.
Heaviest (>2.0 g/cm³)
- PTFE (virgin): 2.14–2.20
- PTFE (15% carbon): 2.08–2.12
- PTFE (25% glass): 2.28–2.32
Best for: chemical seals, electrical insulation, low-friction bearings.
Frequently Asked Questions
What is the density of plastic in g/cm³?
Plastic density in g/cm³ ranges from 0.90 (polypropylene) to over 2.20 (PTFE). Most common engineering plastics fall between 1.0 and 1.5 g/cm³. To convert to kg/m³, multiply by 1000 — so ABS at 1.05 g/cm³ is 1050 kg/m³.
What is the density of plastic in kg/m³?
Common values in kg/m³: PP 900–910, HDPE 940–960, ABS 1040–1060, Nylon 6/6 1130–1150, Polycarbonate 1190–1220, POM/Delrin 1410–1420, PTFE 2140–2200 kg/m³.
Which plastic has the lowest density?
Polypropylene homopolymer (0.90–0.91 g/cm³) is the lightest common engineering plastic. LDPE, UHMW-PE, and HDPE are also below 1.0 g/cm³ — all float in water. Below 0.9 g/cm³ you enter foam territory (rigid PU foam, expanded polystyrene), which are not solid stock forms.
Why does density vary between plastic grades?
Fillers (glass, carbon), crystallinity level, colourants, and moisture content all affect density. A 30% glass-filled grade is typically 15–25% denser than the unfilled version. Higher crystallinity (from slower cooling) also increases density in semi-crystalline polymers like POM, Nylon, and HDPE.
How do I convert plastic density from g/cm³ to kg/m³?
Multiply by 1000. 1 g/cm³ = 1000 kg/m³ exactly. This works because 1 cm³ = 0.000001 m³ and 1 g = 0.001 kg, so the ratio is 0.001 ÷ 0.000001 = 1000. Example: PTFE at 2.16 g/cm³ = 2160 kg/m³.
Calculate Weight from Density
Use any of our material-specific calculators to apply these density values to sheet, rod, and tube dimensions — metric or imperial.