What the Filament Spool Weight Calculator Does
Before starting a multi-hour 3D print on a partially used spool, you need to know how many grams and meters of filament remain on the reel. Because the plastic or cardboard spool hub itself weighs between 130 g and 250 g, weighing a partial spool on a digital kitchen scale gives you the gross weight (`filament + empty spool`).
MeshKit's Filament Spool Weight Calculator subtracts the empty spool tare weight for 14 popular filament brands (or a custom tare weight you measured), calculates net remaining filament in grams, converts that weight into remaining length in meters (`m`) for `1.75 mm`, `2.85 mm`, or `3.00 mm` diameter across 10 polymers, reports percentage remaining for spools from `250 g` to `5 kg`, and checks whether your next print job has enough filament to finish safely.
How to Check How Much Filament Is Left on a Spool in 4 Steps
- Weigh Your Spool on a Digital Scale: Place the partial spool on a kitchen or postal scale set to grams (`g`) and enter that number into Gross Scale Weight.
- Select Your Spool Brand & Type: Choose your manufacturer and spool material (for example, Bambu Lab reusable plastic `250 g`, Bambu Lab cardboard `132 g`, Polymaker cardboard `140 g`, Prusament hex `202 g`, or Custom Tare).
- Pick Spool Capacity, Diameter & Polymer: Select the nominal spool size (`250 g`, `500 g`, `1 kg`, `2 kg`, `3 kg`, `5 kg`), filament diameter (`1.75 mm` or `2.85 mm`), and material density (`PLA 1.24`, `PETG 1.27`, `ABS 1.04`, etc.).
- Verify "Will My Next Print Finish?": Enter the grams required by your slicer in Section B to see whether the spool has sufficient margin.
Worked Examples (Golden Vectors C7, C8 & C9)
Gross Scale = 412 g | Empty Tare = 250 g ⇒ Net Filament = 412 − 250 = 162 g (16.2% of 1 kg)
Grams per Meter = π × (0.175 cm ÷ 2)² × 100 × 1.24 = 2.9825 g/m
Remaining Length = 162 g ÷ 2.9825 g/m = 54.3 m
Example C9 (500 g Net PETG at 2.85 mm Diameter):
Grams per Meter = π × (0.285 cm ÷ 2)² × 100 × 1.27 = 8.1018 g/m
Remaining Length = 500 g ÷ 8.1018 g/m = 61.7 m
Technical Limitations & Batch Variance
Empty spool tare weights listed in our presets are typical values (`last updated 2026-11-01`). Filament manufacturers periodically revise injection molds or cardboard core wall thickness, which can shift empty spool weight by `±5–15 g` between production batches. Additionally, cardboard spools absorb `3–6 g` of ambient moisture before filament drying. For critical end-of-spool prints, keep at least a `15 g` safety margin or weigh an empty spool from the same batch once and enter it via Custom empty spool tare (g).
Frequently Asked Questions
How much does a full 1 kg spool of PLA weigh with the spool included?
A fresh 1 kg (`1,000 g`) spool weighs `1,000 g + empty_spool_tare`. On a `132 g` cardboard spool (Bambu/Elegoo), a full spool weighs roughly `1,132–1,145 g`. On a `250 g` reusable ABS spool, a full spool weighs roughly `1,250 g`.
What happens if my scale weight is lower than the selected empty spool tare?
If gross scale weight is less than the tare weight (for example, `200 g` on a `250 g` reusable spool preset), MeshKit reports `0 g` net filament and displays a warning reminding you to verify whether the filament is wound on a lighter cardboard core (`~132–140 g`).
How many meters of filament are on a 1 kg 1.75 mm PLA spool?
At `1.24 g/cm³` density and `1.75 mm` diameter, PLA weighs `2.9825 g/m`, so `1,000 g` equals approximately `335.3 meters`.
Where can I see the full table of all empty spool weights at once?
Visit our crawlable Empty Filament Spool Weight Database for the complete brand comparison chart.