Byte & Bit Unit Converter

Your new SSD says “1 TB” on the box but Windows shows 931 GB. Your ISP promises “500 Mbps” but files download at 62 MB/s. Your Docker image is “2.3 GB” on Docker Hub but takes 2.14 GiB of disk space. None of these numbers are wrong — they’re in different units, and the difference matters when you’re sizing cloud storage, estimating download times, or figuring out why your disk is “missing” 70 GB.

Why This Converter (Not Google or Mental Math)

Google can convert “1 TB to GB” but doesn’t distinguish SI from IEC — it gives you 1,000 GB and ignores the GiB question entirely, which is usually the one you’re actually asking. Quick mental math breaks down at petabyte scale or when mixing bits and bytes across SI and IEC standards.

This converter shows both SI and IEC results side by side for the same input, so you immediately see the gap. It also handles bits (for network speeds) alongside bytes (for file sizes) — the ÷ 8 conversion that trips people up when comparing download speeds to file sizes. Everything runs in your browser; your numbers never leave your device.

What Is a Byte/Bit Unit Converter?

A byte unit converter translates data size values between all common storage and networking units. This converter supports two standards simultaneously: the SI decimal system (KB, MB, GB — powers of 1,000) used in storage marketing and the IEC binary system (KiB, MiB, GiB — powers of 1,024) used by operating systems and RAM specifications. Understanding the difference is essential for avoiding the “missing storage” confusion every computer user encounters.

SI Decimal vs IEC Binary: The Core Difference

The most common source of confusion in computing: why does a “1 TB” hard drive show as ~931 GiB in Windows?

SI Decimal (powers of 1,000)

Where you see SI decimal: hard drive packaging, SSD specs, cloud storage pricing, file download sizes, network speeds (though network uses bits, not bytes).

IEC Binary (powers of 1,024)

Where you see IEC binary: RAM specifications, operating system file explorers (Windows Explorer, macOS Finder historically), virtual machine disk sizes, Docker image layers.

Why the Discrepancy Grows with Size

A “1 TB” drive contains exactly 1,000,000,000,000 bytes. Your OS, which counts in powers of 1,024, divides that by 1,073,741,824 and displays ~931 GiB. Nothing is missing — it’s a unit labeling difference.

Bits vs Bytes

Critical: networking speeds are measured in bits per second (Mbps, Gbps), while file sizes use bytes (MB, GB). A 100 Mbps connection downloads at ~12.5 MB/s. Always check whether you’re reading bits (b) or bytes (B).

Download speed in MB/s = Mbps ÷ 8
Example: 100 Mbps ÷ 8 = 12.5 MB/s

Common Conversions Reference

File Sizes

Network Speeds

How to Convert Between Byte Units

All conversions route through the bit as the fundamental unit:

bits = input_value × bits_per_unit
result = bits ÷ bits_per_target_unit

SI Decimal examples:

1 MB to KB:  1 × 8,000,000 bits ÷ 8,000 = 1,000 KB
1 GB to MB:  1 × 8,000,000,000 bits ÷ 8,000,000 = 1,000 MB

IEC Binary examples:

1 MiB to KiB:  1 × 8,388,608 bits ÷ 8,192 = 1,024 KiB
1 GiB to MiB:  1 × 8,589,934,592 bits ÷ 8,388,608 = 1,024 MiB

Cross-standard example:

1 GB (SI) to GiB (IEC):
  1 GB = 1,000,000,000 bytes
  1 GiB = 1,073,741,824 bytes
  1 GB ÷ 1,073,741,824 ≈ 0.9313 GiB

Practical Use Cases

Checking Disk Space

Your 500 GB SSD is advertised as 500,000,000,000 bytes. Windows shows:

• 500,000,000,000 ÷ 1,073,741,824 = 465.66 GiB

macOS shows the same drive as ~500 GB (macOS switched to decimal in 10.6 Mountain Lion). Linux df shows it in GiB by default.

Calculating Download Time

You need to download a 4.2 GiB file on a 50 Mbps connection:

1. Convert 4.2 GiB to bits: 4.2 × 1,073,741,824 × 8 = 36,073,013,453 bits
2. Divide by 50,000,000 (50 Mbps) = ~721 seconds ≈ 12 minutes

RAM vs Storage

RAM is measured in true binary GiB (1,073,741,824 bytes). A “16 GB RAM” module contains exactly 16 × 1,073,741,824 bytes. This is one case where “GB” actually means GiB in most usage — hardware manufacturers use binary for RAM, decimal for storage.

Data Center & Cloud Storage

Cloud providers bill in decimal GB (Amazon S3, Google Cloud Storage, Azure Blob). When you pay for “1 TB” of storage, you get 1,000,000,000,000 bytes — not 1,099,511,627,776 bytes. Calculate your actual storage needs using decimal (SI) units when planning cloud costs.

Historical Context

Before 1998, “kilobyte” universally meant 1,024 bytes because computer memory is addressed in powers of 2. The IEC standardized the KiB/MiB/GiB prefixes in 1998 to eliminate ambiguity. However, storage manufacturers had already been using decimal definitions for decades. Today:

• Storage hardware (HDD, SSD, flash drives): decimal GB
• RAM: binary GiB (though often labeled GB)
• OS file sizes: varies — macOS uses decimal (GB), Windows uses binary (GiB but labels it GB until Windows 11)
• Network speeds: always bits per second with decimal prefixes (1 Gbps = 10^9 bits/s)

Frequently Asked Questions

Why does my 1 TB drive show 931 GB in Windows? Windows reports in GiB (powers of 1,024) but labels them “GB.” 1,000,000,000,000 bytes ÷ 1,073,741,824 bytes/GiB = 931.32 GiB. The drive is exactly as advertised — the OS uses a different scale.

Is 1 MB = 1,000 KB or 1,024 KB? In the strict SI standard: 1 MB = 1,000 KB. In the IEC binary standard: 1 MiB = 1,024 KiB. In informal usage, both have been used for MB historically, which is why the IEC binary prefixes (MiB, GiB) exist.

How many bytes in a gigabyte? Exactly 1,000,000,000 bytes (SI decimal), or 1,073,741,824 bytes (IEC gibibyte). Always clarify which standard is being used.

What is a petabyte? 1 PB = 1,000 TB = 1,000,000 GB = 1,000,000,000 MB = 1 quadrillion bytes (10^15). The Internet produces approximately 2.5 quintillion bytes (2,500,000 PB) of data per day.

Is my data sent to a server? No. All conversions are computed entirely in your browser using JavaScript. No data is transmitted to any server. Your values remain completely private.