Filament bundles: are they worth it?

Filament is sold three ways: a single 1 kg spool, a bundle of several full spools, or a set of small sample spools in many colours. They look like the same product at different sizes. Priced per kilogram, they are three very different deals, and the one that looks most generous on the listing is usually the worst.

What each pack size actually costs

These are PLA and PLA+ listings on Amazon UK, grouped by the total weight in the pack, at the time of writing. The headline price is what you pay at checkout; the price per kilogram is what the plastic costs.

Two things stand out. The average multi-kilo bundle costs about half as much per kilogram as the average single spool. And the average small sample set costs about three times as much as a single spool — you are paying for a dozen little reels, the packaging and the variety, not for plastic.

Look at the “cheapest” column as well, though, because it tells a different story. The very cheapest single spool (£7.59/kg) is within a pound of the very cheapest bundle (£6.60/kg). Bundles are much cheaper on average because there are few expensive ones, not because the floor is dramatically lower. If you shop carefully for single spools, a bundle saves you perhaps 10–15%, not 50%.

The four kinds of bundle

• Same-colour multi-kilo packs — two to ten spools of one colour, usually black, white or grey. The purest version of the deal: maximum saving, zero variety. Right for anyone printing functional parts in volume.
• Mixed-colour full-spool bundles — four or more 1 kg spools in different colours. The saving is nearly as good, and this is the bundle most people actually want. The catch is that the seller chooses the colours, and there is nearly always one you would never have picked.
• Refill packs — coils with no plastic reel, sold for reusable spools. Often the cheapest per kilogram of all, and less waste, but useless without a compatible reel, and not every refill fits every reel.
• Sample and small-spool sets — eight to twenty reels of 100–250 g each. Poor value by weight, good value as an experiment.

When a bundle is the right buy

• You already know the brand prints well on your machine. This is the condition that matters most. A bundle multiplies whatever the first spool was: four good spools or four bad ones.
• You will use it within a few months. Sealed spools keep for a long time. Opened ones do not, so the question is how many you will have open at once.
• The colours are ones you get through. Black, white and grey disappear quickly. A bundle of those is a bundle you will finish.
• You print in batches. Running out of a colour halfway through a set of matching parts means a shade mismatch from a different batch. A bundle bought together is far more likely to match.
• You have somewhere dry to keep it. Four spools need a sealed box and desiccant. See filament storage.

When a bundle is a false economy

• It is your first order. You do not yet know what you like, what you print, or whether this brand suits your printer. See your first filament order.
• You are buying it for the colours. If you want six colours, six kilograms is a great deal of plastic to get them. Count how many objects you would really print in each.
• The saving is against the wrong comparison. A bundle at £11/kg looks excellent next to a £20 spool and ordinary next to a £9 one. Compare it with the cheapest comparable single spool, not the average.
• One colour in the set is unusable to you. A five-spool bundle with one colour you will never print is really a four-spool bundle at a higher price. Divide the price by the spools you will use.

Reading a bundle listing properly

Bundle listings are where filament pricing is most confusing, and occasionally misleading. Check four things before you trust the number:

• The total weight, not the spool count. “10 rolls” can mean ten 1 kg spools or ten 250 g ones. Find the total in kilograms.
• Which variant the price belongs to. Many listings share one page across several pack sizes, and the price shown may be for the smallest one. If a bundle looks impossibly cheap, select the variant and check the price again.
• Net weight versus spool weight. A 1 kg spool is a kilogram of filament plus roughly 150–250 g of reel. The filament weight is what you are buying.
• Whether the colours are fixed or random. “Random colour” bundles are cheaper for a reason.

We work the price per kilogram out from the total filament weight on every listing so that a 4 kg bundle and a 1 kg spool can be compared directly, and we withhold the figure altogether when it comes out implausibly low, because that nearly always means the price belongs to a different variant. Bulk and multi-pack filament, ranked by £/kg.

What sample sets are actually for

Sample sets are poor value and still worth buying, once, for a specific job: finding out which colours and finishes you like before committing a kilogram to each. A set of twelve small spools for £25 is an expensive way to buy plastic and a cheap way to avoid buying three full spools you never finish.

They are also the sensible way to try finishes that behave differently — silk, matte, glow, glitter — without owning a kilogram of each. If the urge is simply to have many colours, a single rainbow or dual-colour spool gives more variety for less money: how many filament colours do you need.

The sensible sequence

• First order: two single 1 kg spools from one brand.
• Second order: a sample set, if you want to explore colours and finishes.
• Third order onwards: a multi-kilo bundle of the colour you run out of most, from the brand that has printed best.

That order costs slightly more than buying a bundle on day one and wastes far less. Compare bulk and multi-pack filament with PLA and PLA+ single spools, or see all filament ranked by price per kilogram.

Questions people ask

Are filament bundles cheaper than buying single spools?

Yes. On Amazon UK in October 2026, PLA bundles of 4 kg or more averaged about 10.63 pounds per kilogram, against about 21.53 pounds for single 1 kg spools, so the average bundle costs roughly half as much per kilogram. The gap narrows if you shop carefully: the cheapest single spool was 7.59 pounds per kilogram and the cheapest bundle 6.60 pounds.

Should a beginner buy a filament bundle?

No, a beginner should not start with a filament bundle. A bundle commits you to 4 kg or more of one brand before you know whether it prints well on your machine, and opened spools absorb moisture over time. Buy two single 1 kg spools first, then move to a bundle of the colour you use most once you have found a brand you trust.

Are multi-colour filament sample packs worth it?

Multi-colour sample packs are poor value by weight but worth buying once to test colours. Small-spool sets average around 66 pounds per kilogram on Amazon UK, roughly three times the price of a normal 1 kg spool, because you pay for many small reels and packaging. Use one to find out which colours and finishes you like before buying a full kilogram of each.

How long does a 4 kg filament bundle last?

A 4 kg filament bundle lasts a typical hobbyist several months. A small toy uses 20 to 40 grams and a large functional print 200 to 300 grams, so 4 kg is somewhere between 15 large prints and well over 100 small ones. Sealed spools keep for a long time, but once opened a spool should be stored with desiccant and used within a few months.

Does filament go off if I buy too much?

Filament does not expire, but opened spools absorb moisture from the air and print worse as they do: more stringing, popping at the nozzle and weaker parts. Factory-sealed spools stay good for a year or more. Opened PLA kept in a sealed box with desiccant is fine for months, and damp filament can usually be recovered in a filament dryer.

What is the cheapest way to buy PLA filament in the UK?

The cheapest way to buy PLA in the UK is a multi-kilo bundle or a refill pack, which reached about 6.60 pounds per kilogram on Amazon UK in October 2026. The cheapest single 1 kg spools were about 7.59 pounds. Always compare the price per kilogram using the total filament weight, since bundle listings often show the price of the smallest variant.

Why is one filament bundle so much cheaper than the others?

A filament bundle that looks impossibly cheap usually has its price attached to a different variant. Many Amazon listings share one page across several pack sizes, and the displayed price can belong to a single spool rather than the 10-roll pack in the title. Select the exact variant and check the total weight in kilograms before trusting the price per kilogram.

What is a filament refill and do I need a special spool?

A filament refill is a coil of filament sold without a plastic reel, designed to be fitted onto a reusable spool. Refills are often the cheapest option per kilogram and create less waste, but you need a compatible reusable spool, and not every refill fits every reel. Check the inner diameter and width before buying.