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Filament Cost Per Print for Different Build Volumes

Quick answer: A print\'s filament cost is its share of the spool: grams used ÷ spool grams × spool price. For example, a 20 cm³ PLA print weighs 20 × 1.24 = 24.8 g, about 2.5% of a 1 kg spool, so it costs about 2.5% of what you paid for the spool.

By the Charland & Co. team · Published by Charland & Co. · Based on published specs and public sources; we have not tested the products discussed.

3D printing is a rewarding hobby, but understanding the cost of your prints is essential for budgeting and planning. Whether you're printing a small keychain or a large model, the amount of filament used depends on the build volume and the printer's settings. This page explains how to calculate the cost of filament based on the volume of a print, using real-world examples and formulas that follow the rules of the HobbyPrinter site.

Understanding Build Volume and Filament Usage

Every 3D printer has a defined build volume, which is the maximum size of an object it can print. This volume is usually measured in cubic millimeters (mm³) or cubic centimeters (cm³). The amount of filament used in a print depends on the build volume, the layer height, the nozzle size, and the infill percentage. For example, a print with a 20% infill will use less filament than one with a 100% infill.

To calculate the cost of a print, you need to know how much filament is used. This is where the math comes in. The first step is to determine the volume of the print in mm³. Then, using the density of the filament and the diameter of the filament, you can calculate the weight of the filament used. Finally, you can use the price per spool to determine the cost per print.

Worked Example: Filament Use and Cost for a 20 cm³ Print

Your slicer reports how much plastic a print needs. Say it shows 20 cm³ of PLA on 1.75 mm filament from a 1,000 g spool.

  1. Mass: PLA density is 1.24 g/cm³ on Prusament's data sheet (Prusament PLA TDS); check your own filament's sheet. 20 × 1.24 = 24.8 g
  2. Share of the spool: 24.8 ÷ 1,000 = 0.0248, about 2.5% of the spool
  3. Cost: print cost = spool price × 0.0248. Prices change often, so check the current spool price at the retailer and multiply.
  4. Length (optional): cross-section = π × (1.75 ÷ 20)² = 0.02405 cm²; length = 20 ÷ 0.02405 ÷ 100 = 8.3 m

Infill, walls and supports change the volume your slicer reports, so always start from the slicer's estimate.

Common Mistakes When Calculating Filament Cost

When calculating filament cost, it's easy to make mistakes if you're not careful. Here are some common errors to avoid:

  1. Using the wrong density: Different filaments have different densities. For example, PLA has a density of about 1.24 g/cm³, while PETG has a density of about 1.27 g/cm³. Using the wrong density can lead to incorrect calculations.

  2. Forgetting to convert units: The density is given in g/cm³, but the volume is often in mm³. If you don't convert the units correctly, your calculations will be off.

  3. Ignoring infill and layer height: The amount of filament used depends on the infill percentage and the layer height. A higher infill or a lower layer height will use more filament.

  4. Not accounting for overhangs and supports: Some prints require supports or have overhangs that increase the amount of filament used. These should be considered when estimating filament usage.

  5. Using the wrong formula: The correct formula for calculating filament length is: length (m) = grams ÷ (density g/cm³ × π × (diameter mm ÷ 2)²); for example, 1,000 g of PLA at 1.75 mm is 1,000 ÷ (1.24 × 2.405) = 335 m. Using the wrong formula can lead to incorrect results.

How to Use the Filament Cost Calculator

If you're not sure how to calculate filament cost manually, you can use a filament cost calculator. These tools allow you to input the volume of your print, the filament type, the spool price, and the spool weight. The calculator then does the math for you and gives you the cost per print.

To use a filament cost calculator, follow these steps:

  1. Input the volume of your print in mm³.
  2. Select the type of filament you're using (e.g., PLA, PETG, TPU).
  3. Enter the price of the spool and the weight of the spool in grams.
  4. Click "Calculate" to get the cost per print.

Using a calculator can save time and reduce the risk of making calculation errors. It's also a good idea to double-check the results with the manual formula to ensure accuracy.

FAQ: Frequently Asked Questions

Q: What is the difference between PLA and PETG in terms of density?

A: PLA has a density of about 1.24 g/cm³, while PETG has a density of about 1.27 g/cm³. This means that PETG is slightly denser than PLA, which can affect the weight and cost of prints.

Q: How does the diameter of the filament affect the cost of a print?

A: The diameter of the filament affects the length of the filament used. A larger diameter filament will use less filament for the same volume, which can reduce the cost of the print.

Q: Can I use the same formula for different types of filaments?

A: Yes, the formula for calculating filament cost is the same for all types of filaments. However, you need to use the correct density for each type of filament.

Q: How accurate are filament cost calculators?

A: Filament cost calculators are generally accurate if you input the correct information. However, they may not account for factors like overhangs, supports, or infill variations, which can affect the actual amount of filament used.

Q: What should I do if I'm not sure about the density of my filament?

A: If you're not sure about the density of your filament, check the manufacturer's website or product specifications. Most filament manufacturers list the density of their products on their websites.

Who This Is Not For

This page is not for users who are new to 3D printing and are unsure about the basics of filament usage and cost. It assumes a basic understanding of 3D printing concepts such as build volume, layer height, and infill. If you're new to 3D printing, it's recommended to start with a beginner's guide to 3D printing before diving into filament cost calculations.

This page is also not for users who are looking for detailed product recommendations or comparisons. It focuses on the math and formulas used to calculate filament cost, rather than specific products or brands.

Finally, this page is not for users who are concerned about the health effects of 3D printing fumes. If you're concerned about fumes, it's recommended to follow the ventilation guidance provided by your printer and filament manufacturer. Never leave your printer unattended, and always use proper ventilation when printing.

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Conclusion

Understanding how to calculate filament cost based on build volume is an essential skill for any 3D printing hobbyist. By using the correct formulas and considering all factors that affect filament usage, you can accurately estimate the cost of your prints and manage your 3D printing budget effectively.

If you're not sure about the math or formulas, use a filament cost calculator to help you out. These tools can save time and reduce the risk of making calculation errors. It's also a good idea to double-check the results with the manual formula to ensure accuracy.

Remember, the cost of a print depends on a variety of factors, including the build volume, the filament type, the spool price, and the printer settings. By understanding these factors and using the correct formulas, you can make informed decisions about your 3D printing projects and manage your budget effectively.

For more information on filament cost and build volume, check out the related pages listed above. If you have any questions or need further assistance, feel free to contact us at hello@charlandandco.com.

Owner: Charland & Co.
Contact: hello@charlandandco.com

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