83.82 m of 1.75 mm PLA. In PETG, 81.84 m, because PETG is the denser polymer.
A quarter-kilogram is enough for five or six Benchies, or one decent-sized functional part, and that is exactly what sample spools are for.
They are expensive per gram, and that is fine
A 250 g sample sold for ten dollars is $40 a kilogram — 4 cents a gram, against 1.5 to 2.8 cents for the same PLA in a full reel. Roughly double.
You are not buying filament at that price. You are buying the right to find out whether a colour matches, whether a brand's PETG strings on your machine, or whether a specialty material is worth committing a full spool to. Set against the cost of a kilogram of something you turn out to dislike, it is cheap.
The packaging fraction is worse than the price
A 250 g reel weighs 90 to 130 g empty. That is up to a third of the shipped mass being cardboard or plastic, where a 1 kg spool's reel is closer to a fifth.
If you buy samples regularly and pay shipping by weight, the reels are a genuine cost. Refill coils solve it where a brand offers them in small quantities, which few do.
What to actually use them for
- Colour matching. A screen render is not a colour; a printed swatch is.
- New brands. Print your standard test part with a sample before committing to a five-spool order.
- Materials you will use rarely. Soluble supports, glow-in-the-dark, wood-filled — things where a full kilogram would go stale on the shelf before you finished it.
The last one is the strongest case. Filament does not improve with age, and a hygroscopic material bought in bulk and used occasionally is a spool you will end up drying repeatedly — paying for the same kilogram in dryer time over and over.
There is one situation where a sample is a false economy: a material you already know you will use a lot of. Buying four samples to make up a kilogram costs about double and leaves you with four part-reels, four different batches and four sets of colour variation.
Work out the length for any sample size and material in the length and weight converter.