3D Printing Filament Actual Yield in a 1kg Spool Explained

Imagine you're immersed in the world of 3D printing, your design is ready on the screen, and the printer hums to life. Just as you're about to see your creation take shape, a thought crosses your mind: "How long will my current filament last? How much can I actually print with a standard 1kg spool of PLA filament?" This article will answer these questions and help you better estimate your filament usage.

3D printing filaments are typically sold by weight, with common sizes being 500g and 1kg spools. While this makes sense for manufacturing and shipping, it's not always intuitive for users who need to estimate how much they can print. Knowing the length of filament on a spool can help prevent running out mid-print.

For a 1kg spool of 1.75mm diameter PLA filament, the length is approximately 335 meters. This calculation assumes consistent diameter throughout the spool.

The mathematical formula to calculate filament length is:

H = 4W / (π * ρ * D²)

Where:

• H : Filament length (meters)
• W : Filament weight (kilograms)
• π : Pi (approximately 3.14)
• ρ : Filament density (kg/m³)
• D : Filament diameter (meters)

Let's break down the calculation for 1kg of 1.75mm PLA filament:

1. Determine PLA density : PLA typically has a density between 1.21-1.43 g/cm³. We'll use 1.25 g/cm³ (1250 kg/m³) as an average.
2. Convert units : 1.75mm = 0.00175 meters
3. Apply the formula : H = 4 × 1 / (3.14 × 1250 × 0.00175 × 0.00175) ≈ 333.5 meters

This result closely matches our initial estimate of 335 meters. Note that different PLA brands may have slightly different densities, which will affect the calculation. Always check manufacturer specifications for precise values.

The table below shows approximate lengths for various common 3D printing filaments in both 1.75mm and 2.85mm diameters (1kg spools):

Understanding filament length can help with:

• Estimating how many prints you can complete with a spool
• Planning filament purchases more efficiently
• Avoiding failed prints due to running out of filament
• Budgeting for larger projects

Most slicing software can estimate filament usage for a specific print, but knowing the total length on your spool gives you additional context for these estimates.