What it costs to 3D print a QR code

By Tiehl Roberto Matías · 7 min read · Updated 26 October 2026

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A QR keychain weighs less than almost everybody assumes, and a large plate rather more. These figures are not estimates: they are the grams this site's generator calculates for each size, with the settings it comes with.

What each piece weighs

The figures in this table come from the same engine that builds the object you download, an encoder written for this site that runs entirely inside your browser and is described on the about page (in Spanish). When you choose a size in the generator, the site calculates the real volume of the mesh — base plus relief — and converts it to grams with the density of PLA. It is the number shown next to the dimensions, before you download anything.

All of them are measured with the default settings: 3 mm base, 1 mm relief, correction H and a short link, which gives a version 3 code with 29 modules a side.

Of those grams, the base takes 90 %. It is by far the control that moves the figure most, and what you gain and lose by touching it is in the base thickness guide.

Piece	Real dimensions	Weight
Keychain 35 mm	35 × 43 × 4 mm	4.7 g
Keychain 40 mm	40 × 48 × 4 mm	6.1 g
Keychain 50 mm	50 × 58 × 4 mm	9.2 g
Wall plate 90 mm	90 × 95 × 4 mm	27.4 g
Wall plate 120 mm	120 × 124 × 4 mm	47.8 g
Wall plate 150 mm	150 × 155 × 4 mm	74.7 g
Desk stand 70 mm	78 × 34 × 79 mm	32.6 g
Desk stand 90 mm	100 × 36 × 98 mm	49.1 g
Desk stand 120 mm	133 × 46 × 126 mm	78.8 g

There are two things in that table worth looking at twice.

The first is that weight grows with the square of the size, not with the size. A 50 mm keychain does not weigh 25 % more than a 40 mm one: it weighs 52 % more. On a large sign this runs away entirely, and the oversized codes guide (in Spanish) has those grams. And a 150 mm plate weighs almost three times a 90 mm one, even though its side is only 67 % longer. Every time you hesitate between two sizes, that jump is bigger than it looks.

The second is that the desk stand weighs far more than the plate of the same number: 49 g against 27 g at the 90 mm size. It is not that the code part is different, it is that it has a foot. That foot is what keeps it standing, so it cannot be removed, but it explains why a batch of stands empties the spool twice as fast.

How many pieces come out of a spool

This is the figure that actually helps you decide, because it does not age: filament prices change every quarter, but a spool is still 1 kg.

Piece	Units per 1 kg spool
Keychain 35 mm	211
Keychain 40 mm	164
Keychain 50 mm	108
Plate 90 mm	36
Plate 120 mm	20
Plate 150 mm	13
Stand 70 mm	30
Stand 90 mm	20
Stand 120 mm	12

Turning that into money takes one division: the price of the spool divided by the units. If a kilo of PLA costs you whatever it costs today, a 40 mm keychain costs you one hundred and sixty-fourth of that. It comes out ridiculously cheap, and that is exactly why almost nobody prices these correctly: they look at the material, which is the smallest part of the sum.

Watch out for one trap: these pieces use two colours. You draw from two spools, not one. The split is nothing like half and half — the relief is a 1 mm sheet and the base is 3 mm — so the spool of the base colour runs out long before. In round numbers, three of every four parts of filament are base.

How long it takes

Here we have to be honest: only your slicer knows the exact time, because it depends on your profile, your speed, your acceleration and your machine. What can be given is a reliable order of magnitude, and it comes from one simple figure: an ordinary printer with a 0.4 mm nozzle lays down PLA at about 5 to 7 mm³ a second on real average, travel included.

At 6 mm³/s, which is a cautious value:

Piece	Volume	Approximate time
Keychain 35 mm	4.8 cm³	~13 min
Keychain 40 mm	6.1 cm³	~17 min
Keychain 50 mm	9.3 cm³	~26 min
Plate 90 mm	27.7 cm³	~1 h 15
Plate 120 mm	48.2 cm³	~2 h 15
Stand 90 mm	49.5 cm³	~2 h 20
Stand 120 mm	79.5 cm³	~3 h 40

Treat it as an estimate for knowing whether something takes twenty minutes or four hours, not as a billing figure. When you slice, your slicer's number is the one that counts.

On top of those times there is something no table shows: the colour change pause. If you print with a single extruder, the machine stops at 3 mm of height and waits for you to change the filament. That stop lasts however long you take to get there, and if you are doing a batch of twenty keychains on the same plate, it is one pause for all twenty. It is explained in the colour change guide.

The electricity, which hardly counts

A desktop FDM printer draws on average between 80 and 150 W while working: the peak is heating the bed at the start and then it drops considerably, because the heater only comes on in bursts to hold temperature.

At 100 W average, a 90 mm plate taking an hour and a quarter uses about 0.13 kWh. A 120 mm stand taking almost four hours, about 0.37 kWh. On any domestic tariff those figures land well below what the filament for that same piece costs.

Practical conclusion: electricity is not a factor. If you are fine-tuning the cost of your pieces, the time it takes you to set up, peel off and finish each one is worth far more than the power the machine used.

How to price them if you sell them

The classic mistake is to multiply the grams by the price of the filament and add a margin. It gives a number so low it does not cover the time you spent standing at the printer.

A more sensible sum has four parts:

• Material. Price of the spool divided by the units in the table above, times two colours.
• Machine. What the printer cost you spread over the hours you expect it to last. If you paid something for it and you think it will manage two thousand hours, each hour of printing has a cost, even if you do not pay it that day.
• Failures. One piece in ten or fifteen comes out wrong, especially while you are dialling in the colour change. That waste is paid for by the ones that did come out.
• Your time. Preparing the file, loading the plate, waiting for the filament change, peeling it off, cleaning up stringing and checking it scans. This is nearly always the biggest item, and the one most often forgotten.

If you sell in batches, the time per piece drops a lot: twenty keychains on one plate take almost the same setting up as one. That is why a sensible unit price for a single piece and for an order of fifty look nothing alike.

Where the real saving is

In order of real impact:

1. Choosing the size well. By far the biggest mover, because weight goes as the square. Before making the piece bigger, check in the minimum size guide what size you really need. Plenty of 120 mm plates would work just as well at 90.
2. Shortening the link. Fewer characters, lower version, bigger modules and therefore a smaller piece for the same readability.
3. Printing in batches. It saves no material, but it spreads your time and the colour-change pauses across many pieces. How many fit on your bed and how long the plate takes is in the batch guide.
4. Lowering the infill. Last on the list, deliberately: on pieces this thin it barely changes anything, as explained above.
5. What does not save anything: the module shape. Between the hungriest shape and the leanest there is 2 % of the piece, measured in the shapes guide. What it does change is the time, and for the worse.