Resin calculator: how much resin, what it costs, how long it takes

This resin calculator answers three questions before a resin print: how much resin you need, what it costs, and how long the print takes. You get three results:

• Resin needed in ml and grams (and ounces), plus how many bottles that is;
• Resin cost for all copies, and per copy when you print more than one;
• Print time and the number of layers.

You can enter the volume two ways. Type it in, for example from your slicer's readout. Or drop in the model (STL, 3MF, OBJ and other mesh formats): your browser then computes the volume, surface area and height from the triangle mesh. Everything happens in your browser; the file is never uploaded.

Volume from a model is exact for a closed, error-free mesh. If the mesh has holes, it's only approximate; fix it first with the STL repair tool.

1. Part volume: the model's volume, or for a hollow print, the shell's volume.
2. Supports: the support percentage is added to the part volume. Typically 5–30%; more for small figures that need lots of support.
3. Copies: the result is multiplied by the number of copies.
4. Waste: drips, resin left in the vat and resin lost to cleaning are added to the total (5% by default).
5. Weight and cost: ml × density = grams; grams ÷ 1,000 × price per kg = cost. Bottles = grams ÷ bottle size.

Standard resin density is usually 1.05–1.2 g/ml; the default is 1.1 g/ml. The exact value is on the bottle or the technical data sheet. If your resin is priced per liter, the price per kg is the price per liter ÷ density.

A 25 ml figure (about 0.85 fl oz) with 15% supports, 5% waste, one copy, 1.1 g/ml resin at $30/kg and a 1,000 g bottle:

Step	Math	Result
With supports	25 × 1.15	28.75 ml
With waste	28.75 × 1.05	30.2 ml
Weight	30.2 × 1.1	33.2 g (about 1.2 oz)
Cost	33.2 ÷ 1,000 × 30	about $1.00
Bottles	33.2 ÷ 1,000	0.03 bottles

Print time for the same model: 50 mm tall (about 2 in), lifted 5 mm on supports, 50 µm layers, 2.5 s exposure, 5 bottom layers at 30 s, and 6 s of lift and retract per layer.

• layers: (50 + 5) ÷ 0.05 = 1,100 layers;
• normal layer time: 1,100 × (2.5 + 6) = 9,350 s;
• extra for bottom layers: 5 × (30 − 2.5) = 137.5 s;
• total about 9,488 s, or about 2 h 38 min.

The price in the example is only for illustration; enter what you actually pay for your resin.

On larger solid models, most of the resin ends up inside, where it does nothing. Hollow the model in your slicer and only a shell remains, which can cut resin use dramatically.

The calculator estimates the shell volume as surface area × wall thickness, a good approximation for thin walls. If you loaded a model, it uses the real surface area. With a typed-in volume, the surface area is approximated by a cube of the same volume. That's rougher, because a detailed figure has far more surface than a cube.

Example: a cube-shaped 25 ml block has a surface area of about 6 × 25^(2/3) ≈ 51 cm². With a 2 mm wall, the shell is about 51 × 0.2 ≈ 10.3 ml, less than half of the solid 25 ml.

Two rules for hollow prints:

• add at least two drain holes, or trapped liquid resin can crack the part later, and the inside can't be washed;
• keep the wall around 1.5–3 mm, or the part gets fragile.

After hollowing, your slicer shows the exact volume; enter that for a more accurate cost.

A resin (MSLA) printer exposes a whole layer at once, however many parts are on the plate. So print time depends on the height of the tallest part, the layer height, exposure time and lift time, not the number of parts. One figure or ten take the same time if they fit on the plate. Resin use and cost, on the other hand, grow with every copy.

What to know about the settings:

• Lift-off height: the height of the supports under the model, added to the model's height.
• Layer height: 50 µm is standard; at 25 µm you get twice the layers and roughly twice the time.
• Bottom layers: the first few layers get a much longer exposure so they stick to the build plate.
• Lift and retract: 2–10 s per layer depending on the machine; often it's the bigger share of total time. Your slicer shows the exact figure.

The estimate is a guide: real time also depends on your printer's motion profile. For filament (FDM) prints, use the 3D print cost calculator.