Special offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy.

A pgvector vector value uses 4 × dimensions + 8 bytes; halfvec uses 2 × dimensions + 8 bytes. Those figures describe the embedding value only—not the full table, indexes, or database disk footprint. Use them for a first-pass payload estimate, then measure a representative dataset and its indexes in PostgreSQL.

How much space does one pgvector embedding use?

The documented formulas are 4 × dimensions + 8 bytes for vector and 2 × dimensions + 8 bytes for halfvec. vector stores single-precision elements; halfvec stores half-precision elements. The figures below are arithmetic from those formulas, not benchmark measurements. pgvector documentation

Dimensions vector value halfvec value
384 1,544 bytes 776 bytes
768 3,080 bytes 1,544 bytes
1,536 6,152 bytes 3,080 bytes
3,072 12,296 bytes 6,152 bytes

For a quick payload estimate, multiply the per-value figure by the number of rows that will contain embeddings. For example, 100,000 rows with 768-dimensional vector values yield 308,000,000 bytes of vector-value payload by the documented formula. That is not a forecast of provisioned disk: it excludes row and table overhead, indexes, other columns, and storage details.

Why the vector formula is not your database size

The formula estimates the vector value, while PostgreSQL stores values within tables and may also store indexes and TOAST data. PostgreSQL provides separate size functions for inspecting those layers. pg_column_size reports the bytes used by an individual value and can reflect compression when called on a column value; pg_indexes_size measures attached indexes; pg_total_relation_size includes the table, its indexes, and TOAST data. PostgreSQL size functions

Special offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy.
#1 Best Overall
Elebase USB to USB C Adapter for iPhone 18 Pro Max,USBC Car Charger Adapter
  • Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
  • Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
  • Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
  • Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
  • 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.

Run these queries against a representative loaded table and your actual schema:

-- Size of one stored embedding value
SELECT pg_column_size(embedding)
FROM items
WHERE embedding IS NOT NULL
LIMIT 1;

-- Table storage, attached indexes, and combined total
SELECT
  pg_size_pretty(pg_table_size('items')) AS table_size,
  pg_size_pretty(pg_indexes_size('items')) AS indexes_size,
  pg_size_pretty(pg_total_relation_size('items')) AS total_size;

-- Size of one named index
SELECT pg_size_pretty(pg_relation_size('items_embedding_hnsw'));

The query results show observed storage for the database objects you measure; they are more useful for capacity planning than treating the vector-value formula as an exact disk requirement. Measure after loading enough representative data, and include the index you expect to use.

Rank #2
Anker USB-C Hub, 5-in-1 USB Hub for Laptops, 4K HDMI Multiport Adapter
  • 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
  • 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
  • Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
  • 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
  • What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.

How much extra storage can a vector index add?

pgvector uses exact nearest-neighbor search by default. HNSW and IVFFlat provide approximate nearest-neighbor search, trading recall behavior for speed. Indexes can add substantial storage, but there is no universal multiplier: actual size depends on the data and index settings, so build the intended index and measure it.

Approach Search behavior Storage and operational considerations
Exact search without an approximate index Exact nearest-neighbor search by default. No HNSW or IVFFlat index is added; measure the table and any other indexes you retain.
HNSW Approximate search; pgvector describes a better speed/recall tradeoff than IVFFlat. Builds more slowly and uses more memory than IVFFlat, according to the project documentation. Measure the resulting index on your data.
IVFFlat Approximate search; speed and recall depend on index configuration. Compare its measured index size and query behavior with HNSW under your workload.

A pgvector project discussion dated October 3, 2024 reported close to 3.9 GB for each of an IVFFlat and an HNSW index on one million 768-dimensional vectors under particular settings. A maintainer explained that index records include vector data and, for HNSW, neighbor references. This is a single settings-specific example, not a sizing multiplier for other workloads. pgvector project discussion, October 3, 2024

Special offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy.
Rank #3
Sale
Anker USB C Hub, 7in1 Multi-Port USB Adapter, 4K@60Hz USBC to HDMI Splitter
  • Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
  • Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
  • Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
  • Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
  • What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.

Indexes do not have to fit in memory, though pgvector notes that performance is likely better when they do. pgvector documentation

Should you use vector or halfvec?

At the same dimension count, halfvec uses half the element storage shown by the documented formulas. That can reduce the vector payload and may help reduce the working set, but it changes numeric precision. Test retrieval quality and application behavior using representative data before adopting it; the documented storage sizes do not establish equivalent quality for every workload.

Rank #4
Sale
UGREEN USB to USB C Adapter Combo 4-Pack, 10Gbps USB C Converter Space Gray
  • Dual Converters, Infinite Potential:Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
  • Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
  • Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
  • Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
  • Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Support on Ko-Fi

What if your embeddings have more dimensions?

The pgvector README documents vector values up to 16,000 dimensions. The listed HNSW index limits are up to 2,000 dimensions for vector and 4,000 for halfvec; bit indexing is listed up to 64,000 dimensions. These limits differ by type and index, so check the extension version and supported type/index combination for your deployment before selecting a schema. pgvector documentation

For smaller indexes or larger-dimensional workloads, the project documentation also describes half-precision indexing, binary quantization, subvector indexing, and dimensionality reduction. These are design alternatives rather than interchangeable storage guarantees; evaluate their retrieval behavior and application requirements with your data.

Special offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy.
Best Value
Anker USB C Hub, 5-in-1 USBC to HDMI Splitter with 4K Display
  • 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
  • Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
  • Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
  • HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
  • What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.

A practical sizing workflow

  1. Confirm dimensions and row count. Check the embedding model’s output dimension and estimate how many rows will store a non-null embedding.
  2. Calculate value-only payload. Use 4 × dimensions + 8 for vector, or 2 × dimensions + 8 for halfvec if that representation fits your requirements.
  3. Multiply by expected rows. Label the result as a vector-value estimate, not total database storage.
  4. Load representative records. Use the real PostgreSQL version and schema, then inspect value, table, index, and total relation sizes with the size functions above.
  5. Build the intended index. Measure its actual size after creation; if updates and deletes are part of the workload, recheck after representative activity.
  6. Compare tradeoffs before changing design. Evaluate storage alongside query speed, recall behavior, build time, memory use, precision, and application behavior.

Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.