How much data can fit into a parcel locker? InPost as example

Let’s start with something simple, namely the size of parcel lockers.

Package size	Gross price	Description
Size XS	11.99 PLN	Maximum dimensions: 40 x 230 x 400 mm, minimum height: 1 mm, maximum weight: 3 kg. Size available only in the InPost Mobile app.
Size A	16.99 PLN	Maximum dimensions: 80 x 380 x 640 mm, minimum height: 1 mm, maximum weight: 25 kg
Size B	18.99 PLN	Maximum dimensions: 190 x 380 x 640 mm, minimum height: 81 mm, maximum weight: 25 kg
Size C	20.99 PLN	Maximum dimensions: 410 x 380 x 640 mm, minimum height: 191 mm, maximum weight: 25 kg
Size D	36,99 PLN	Maximum dimension: 500 x 500 x 800, maximum weight: 25 kg
Fuel surcharge	0%	The fuel surcharge is not applied for shipments under the Retail Price List.

Prices based on April 2025.

Of course, we’ll take the largest dimensions. And MicroSD cards, since they’re the smallest.

MicroSD card specification:

Dimensions: 15 x 11 x 1 mm = 165 mm³
Weight: 0.25 g
maximum capacity of a MicroSD card: 128 TB

Size D

maximum dimensions: 500 x 500 x 800 mm
minimum height: n/a
maximum weight: 25 kg
data transfer speed: 24–48h
Locker volume: 200 liters

Assuming capacity based on volume:

Maximum number according to volume:
200 liters / 165 = 1,212,121 cards
1,212,121 × 128 TB = 15.64 zettabytes
Data transfer rate: 90.509–181.02 PB/s

So that’s it, mystery solved, we can all go home? Not quite.

The weight of a single MicroSD card is 0.25 g. That’s over a million cards, which in theory would weigh 303.0303 kg. A bit too much… And not everyone will use a courier parcel of size D, so let’s move on to the parcel locker.

Size C

maximum dimensions: 410 x 380 x 640 mm
minimum height: 191 mm
maximum weight: 25 kg
parcel delivery speed: 24–72h
Locker volume: 99.68 liters

Now let’s repeat the exact same process:

Maximum number according to volume: 99.68 liters / 165 ≈ 604,921 cards
604,921 × 128 TB = 77.43 EB
Data transfer rate: 448.09–896.18 TB/s (48/24)

So over half a million MicroSD cards would, in theory, weigh 151.2302 kg. That’s still too much for the parcel locker, which allows only 25 kg.

So:

Maximum number according to weight = 25 kg / 0.25 g = 100,000 cards
100,000 cards × 128 TB = 12.8 EB
If the shipment is delivered within 24–48 hours, the transfer is:
12.8 EB / 24–48h = 74–148 GB/s

So we’ve got it, the ultimate limit is 12 exabytes? Theoretically yes, practically no.

Just the readout would take 9 hours 1 minute 27.31 seconds per card, and that’s assuming the fastest Express standard up to 3940 MB/s – which equals about 108 years, or 39 days if you somehow managed to use 1000 adapters, controllers, etc. Of course, assuming ideal conditions and not average read speeds. That’s 1.3 times the average human lifespan in the USA (≈ 80.1 years).

For comparison, the readout for the volumetric capacity of Size C and Size D would be, respectively: 652.78 years and 1308.11 years. The first is 23 times the length of a human generation (≈ 28 years), and the second is 1.2 times the duration of the Byzantine Empire (≈ 1100 years).

Maybe a more realistic solution would be useful – one you might actually live to see?

Best capacity and read speed ratio

We ask: What storage medium offers the best combination of capacity and read speed per delivery, given parcel locker constraints?

3. 2.5" SATA SSDs

Typical size: 70 × 100 × 7 mm = 49,000 mm³
weight: 100g
Read speed: 600 MB/s
capacity: 2 TB
data: 250 drives × 2 TB = 500 TB per shipment
transfer: 23.15 Gb/s-46.3 Gb/s
Read time for one drive: 2 TB / 600 MB/s (SATA limit) = 55 minutes 33.33 seconds * 250 = 9 days 15 hours 28 minutes 52.5 seconds

2. Alternative: U.2/U.3 NVMe SSDs

Typical size: 70 × 100 × 15 mm = 105,000 mm³
weight: 200g
Read speed = 7000 MB/s
capacity = 16 TB
data: 125 drives max = 2 PB per shipment
Transfer: 92.59-185.2 Gb/s
Read time for one drive: 16 TB / 7000 MB/s = 38 minutes 5.714 seconds * 125 = 3 days 7 hours 21 minutes 54.25 seconds

1. Top Choice: M.2 NVMe SSDs (in trays/enclosures)

Typical size = 22 × 80 × 4 mm = 7,040 mm³
weight: ~10g
Read speed: 3,500 MB/s
capacity = 8 TB
data: 8 TB × 2500 = 20 PB of data
Transfer: from 925.9 Gb/s to 1.852 Tb/s
Read time for one drive: 38 minutes 5.714 seconds * 2500 = 66 days 3 hours 18 minutes 5 seconds

Trivia

Floppy 💾

Floppy Disk Specs (3.5")
- Dimensions: 90 × 94 × 3.3 mm
- Volume per disk: ~28.5 cm³ = 0.0285 L
- Weight per disk: ~50 g
- Capacity: 1.44 MB (or 0.00144 GB, or 1.37 MiB)
Max by Weight
- 25.000g/50g per floppy = 500 floppies
- 500*1.44 MB = 720 MB
Max by Volume
- 99.68l/0.0285l per floppy = 3494 floppies
- 3494 * 1.44 MB = 5.03 GB
Height Constraint
- 191 mm/ 3.3 mm = 57 floppies per stack
- 3 * 4 * 57 = 684 disks max under height constraint
- 684 * 1.44MB = 985 MB

compact discs

Specs
- Diameter: 120 mm = 12 cm
- Thickness: 1.2 mm
- Weight per disc: 16 grams
- Capacity: 200 GB
by weight
- 25,000 g/ 16 g/disc = 1562 discs
- 1562 * 200 = 312.4 TB
by volume:
- V=πr 2h=π×(6 cm) 2×0.12 cm≈13.57 cm3=0.0136L
- 99.68 L / 0.0136 = 7335
- 7335 * 200 = 1.467 PB
Min Height (191 mm) Limit
- Each disc is 1.2 mm thick -> Max stacked discs in one vertical column: 191 mm / 1.2 mm = 159 discs per stack
- or could arrange multiple stacks side-by-side: Each disc is 120 mm in diameter → stacks need ~125 mm spacing: Fit 3×3 stacks (125 × 3 = 375 mm in both directions)