# 3D print weight calculator

> Drop an STL to estimate print weight in grams for PLA, PETG, ABS or resin, with a density table and an infill formula for real FDM prints. Free, runs in your browser, no upload.

Source: https://freestlviewer.com/stl-weight-calculator/  
Updated: October 22, 2026

Drop an STL, 3MF or OBJ to estimate how many grams of PLA, PETG, ABS or resin it needs. The model is measured in your browser and never uploaded. The tool is interactive: open https://freestlviewer.com/stl-weight-calculator/ and drop a file onto the page.

## How to use it

1. Drag an `.stl` onto the drop zone above (3MF, OBJ, STEP and other formats
   work too), or click **Choose 3D file**.
2. The analysis panel opens with the model's **volume** and its **estimated
   weight**. Switch the material between **PLA, PETG, ABS and resin** to
   compare.
3. Check the **watertightness** line: the weight is only reliable for a
   closed mesh.

The figure is for a solid part at 100 % infill. For other materials, or to
estimate a real FDM print, use the table and formula below with the volume and
surface area the panel shows.

## Density of common filaments and resin

| Material | Density (g/cm³) | 1 cm³ weighs |
| --- | --- | --- |
| PLA | 1.24 | 1.24 g |
| PETG | 1.27 | 1.27 g |
| ABS | 1.04 | 1.04 g |
| ASA | 1.07 | 1.07 g |
| TPU (95A) | 1.21 | 1.21 g |
| Nylon (PA6/PA66) | 1.14 | 1.14 g |
| Polycarbonate | 1.20 | 1.20 g |
| Standard resin | 1.15 | 1.15 g |

These are typical values for unfilled materials. Filled filaments differ a lot
— metal-filled PLA can be two to three times heavier — so for anything you
are quoting, use the figure on the spool's datasheet. The
[density reference](https://freestlviewer.com/blog/filament-density-reference/) lists more materials and
converts spool weight to metres.

## From solid weight to a realistic FDM estimate

A slicer does not fill the model solid. It prints a shell — a few perimeter
walls plus solid top and bottom layers — and fills the inside with sparse
infill. A useful approximation:

```
shell volume (cm³)    ≈ surface area (cm²) × shell thickness (cm)
interior volume (cm³) = volume − shell volume
printed volume (cm³)  ≈ shell volume + interior volume × infill
weight (g)            ≈ printed volume × density
```

With two walls from a 0.4 mm nozzle, a shell thickness of about **0.08–0.09
cm** (0.8–0.9 mm) is a fair assumption. The analysis panel shows both the
volume in cm³ and the surface area in cm².

**Worked example — a 20 mm cube in PLA at 15 % infill:**

- volume = 8.00 cm³, surface area = 24.00 cm²
- shell ≈ 24 × 0.08 = 1.92 cm³
- interior = 8.00 − 1.92 = 6.08 cm³, × 0.15 = 0.91 cm³
- printed ≈ 1.92 + 0.91 = 2.83 cm³ → **≈ 3.5 g of PLA**

The solid figure would be 9.9 g. For thin-walled or small parts the shell
dominates, and the estimate gets close to the solid weight; for big, chunky
parts infill dominates and the gap widens. Supports and brims come on top.

## Resin prints

Resin parts are usually printed solid or hollowed, not with sparse infill, so
the solid weight is a good estimate for a solid print. Resin is sold by volume
as well as by weight: 1 cm³ of model is about 1 ml of resin. Add supports and
the film left on the vat and build plate.

## Estimating cost

```
cost = grams × spool price ÷ spool weight in grams
```

A 35 g part from a 1 kg spool that cost 20 (in any currency) uses about 0.70 of
material. Electricity, wear and failed prints are extra.

## Common reasons the number looks wrong

- **Wrong units.** If a part reads tiny, the STL was probably exported in
  inches or metres; see [STL units](https://freestlviewer.com/blog/stl-units-mm-vs-inches/).
- **Open mesh.** Holes make volume — and weight — unreliable.
- **Overlapping bodies.** Intersecting shells are counted twice.
- **Hollow by design.** A model that is already a thin shell (a vase-mode
  print, for example) weighs what its walls weigh.

## On your phone

The calculator works in a phone browser too. The Mes3D app for iPhone, iPad and
Android adds a wall-thickness view and problem-area highlighting, so you can
see why a part is heavier or weaker than expected, plus cross-sections and
resizing to exact dimensions.

## Frequently asked questions

### How do I calculate how much filament a print uses?

Multiply the model's volume in cm³ by the filament's density in g/cm³ — PLA is about 1.24 — to get grams for a solid print. Real FDM prints are walls plus sparse infill, so the slicer's figure is usually well under that solid number; the infill formula on this page gives a closer estimate.

### How much does 1 cm³ of PLA weigh?

About 1.24 g. PETG is about 1.27 g, ABS about 1.04 g, ASA 1.07 g, TPU 1.21 g and standard photopolymer resin about 1.15 g per cm³. Check the spool's datasheet for exact values.

### Why is the calculator's weight higher than my slicer's?

The calculator reports the weight of the solid model at 100 % infill, which is the upper bound. A slicer knows your wall count, layer settings and infill percentage, and adds supports. Use the solid figure to compare models and the slicer for the final number.

### How do I estimate print cost?

Cost = grams × spool price ÷ spool grams. A 35 g part from a 1 kg spool that cost 20 costs about 0.70 in material.