MB to GB Converter - Bits to PB, Instant Table

If you have ever wondered why your "500 GB" hard drive only shows 465 GB in Windows, or why a "1 TB" cloud storage plan seems to hold less than you expected, the answer lies in how data storage units are defined.

There are two competing systems, binary and decimal, and the difference between them causes confusion for millions of people.

This data storage converter handles conversions between all standard data units, from bits and bytes up through kilobytes, megabytes, gigabytes, terabytes, and petabytes. Critically, it supports both binary units (KiB, MiB, GiB, TiB, where 1 KiB = 1,024 bytes) and decimal units (KB, MB, GB, TB, where 1 KB = 1,000 bytes), so you can convert between the two systems that operating systems and storage manufacturers use differently.

Whether you are calculating how many photos fit on a memory card, estimating cloud storage needs, figuring out download times for large files, or just trying to understand why storage capacities never seem to match their advertised numbers, this converter gives you exact results using both measurement standards.

Binary vs Decimal: Why Your Storage Seems Smaller

The core confusion in data storage units comes from a historical naming collision. Computer memory operates in powers of 2 (binary), but the metric system uses powers of 10 (decimal). For decades, the same prefixes (kilo, mega, giga) were used for both systems, creating persistent confusion.

Decimal (SI) units use powers of 1,000:

1 Kilobyte (KB) = 1,000 bytes
1 Megabyte (MB) = 1,000 KB = 1,000,000 bytes
1 Gigabyte (GB) = 1,000 MB = 1,000,000,000 bytes
1 Terabyte (TB) = 1,000 GB = 1,000,000,000,000 bytes

Binary (IEC) units use powers of 1,024:

1 Kibibyte (KiB) = 1,024 bytes
1 Mebibyte (MiB) = 1,024 KiB = 1,048,576 bytes
1 Gibibyte (GiB) = 1,024 MiB = 1,073,741,824 bytes
1 Tebibyte (TiB) = 1,024 GiB = 1,099,511,627,776 bytes

The practical impact. Hard drive manufacturers use decimal units because it produces larger-sounding numbers. A drive advertised as "1 TB" contains 1,000,000,000,000 bytes. But Windows reports storage in binary units (though it labels them as "GB"), so that same drive shows as approximately 931 GB (actually 931 GiB). The "missing" 69 GB is not defective storage; it is a labeling discrepancy. The larger the drive, the bigger the apparent discrepancy. A 4 TB drive shows as about 3.63 TB in Windows.

The Complete Data Unit Hierarchy

From smallest to largest, here is how data storage units scale in both systems.

Bit. The smallest unit of data. A single binary digit, either 0 or 1. All digital data is ultimately composed of bits. Eight bits make one byte.

Byte (B). Eight bits. A byte can represent a single character (letter, digit, or symbol) in ASCII encoding. It is the fundamental addressable unit in most computer architectures.

Kilobyte (KB) / Kibibyte (KiB). 1 KB = 1,000 bytes (decimal). 1 KiB = 1,024 bytes (binary). A typical plain text email without attachments is a few kilobytes. A small text file might be 1 to 10 KB.

Megabyte (MB) / Mebibyte (MiB). 1 MB = 1,000,000 bytes (decimal). 1 MiB = 1,048,576 bytes (binary). A high-resolution JPEG photo is typically 3 to 10 MB. A three-minute MP3 song is about 3 to 5 MB. An average smartphone app is 50 to 200 MB.

Gigabyte (GB) / Gibibyte (GiB). 1 GB = 1,000,000,000 bytes (decimal). 1 GiB = 1,073,741,824 bytes (binary). A standard-definition movie is roughly 1 to 2 GB. An hour of HD video is about 3 to 5 GB. Most smartphones today have 64 to 512 GB of storage.

Terabyte (TB) / Tebibyte (TiB). 1 TB = 1,000,000,000,000 bytes (decimal). 1 TiB = 1,099,511,627,776 bytes (binary). Consumer hard drives commonly range from 1 to 20 TB. One terabyte can hold approximately 250,000 photos (at 4 MB each) or 500 hours of standard-definition video.

Petabyte (PB) / Pebibyte (PiB). 1 PB = 1,000 TB (decimal). 1 PiB = 1,024 TiB (binary). Petabyte-scale storage is used by large organizations, cloud providers, and data centers. The entire Library of Congress printed collection is estimated at about 10 TB if digitized, so one petabyte would hold roughly 100 Libraries of Congress.

How Different Platforms Report Storage

One of the most confusing aspects of data storage is that different systems use different conventions for the same numbers.

Windows reports storage sizes using binary math (powers of 1,024) but labels them with decimal prefixes (GB, TB). So when Windows says a file is "1 GB," it actually means 1 GiB (1,073,741,824 bytes). This is technically incorrect labeling but has been the convention since the earliest days of DOS.

macOS switched to decimal units starting with Mac OS X Snow Leopard (version 10.6) in 2009. When macOS says a file is "1 GB," it means exactly 1,000,000,000 bytes. This matches the drive manufacturer’s definition, so Macs tend to show storage capacity closer to the advertised number.

Linux varies by distribution and tool. Many Linux tools support both conventions and use the correct IEC prefixes (KiB, MiB, GiB) when reporting binary values.

iOS and Android generally follow the decimal convention like macOS, reporting storage in powers of 1,000.

Cloud storage providers (Google Drive, Dropbox, iCloud, OneDrive) typically use binary units for measuring your usage, meaning 1 GB of your quota equals 1,073,741,824 bytes. But this varies by provider, so your mileage may differ.

Data Transfer Rates: Bits vs Bytes

Internet speeds are almost always advertised in bits per second, while file sizes are almost always measured in bytes. This creates another common source of confusion.

Key relationship: 1 byte = 8 bits. So 1 megabyte (MB) = 8 megabits (Mb).

Practical example: If your internet plan advertises "100 Mbps" (megabits per second), your maximum theoretical download speed is 100 / 8 = 12.5 megabytes per second. A 1 GB file would take approximately 80 seconds to download at full speed (1,000 MB / 12.5 MB per second). In practice, overhead and network conditions mean actual speeds are typically 60% to 80% of the theoretical maximum.

Common internet speed conversions:

25 Mbps = 3.1 MB/s (basic streaming)
100 Mbps = 12.5 MB/s (HD streaming, moderate downloads)
300 Mbps = 37.5 MB/s (multiple 4K streams, fast downloads)
1 Gbps = 125 MB/s (very fast, large file transfers)

When comparing internet plans, always check whether the speed is listed in Mbps (megabits) or MBps (megabytes). The capitalization of the "b" matters: lowercase "b" means bits, uppercase "B" means bytes.

Storage Capacity Planning

Whether you are choosing a phone, laptop, external drive, or cloud storage plan, knowing how much storage you actually need prevents both overpaying and running out of space.

Photo storage estimates (per 1,000 photos):

Smartphone photos (12 MP, HEIC): approximately 2 to 4 GB
Smartphone photos (48 MP, RAW): approximately 30 to 50 GB
DSLR photos (24 MP, JPEG): approximately 5 to 8 GB
DSLR photos (24 MP, RAW): approximately 20 to 30 GB

Video storage estimates:

1 hour of 1080p video: approximately 3 to 6 GB
1 hour of 4K video: approximately 10 to 20 GB
1 hour of 4K at 60fps: approximately 20 to 40 GB

Music storage estimates:

1,000 songs (MP3, 256 kbps): approximately 3 to 4 GB
1,000 songs (FLAC, lossless): approximately 25 to 40 GB

Application and game sizes:

Average mobile app: 50 to 200 MB
Average desktop application: 200 MB to 2 GB
Modern AAA game: 50 to 200 GB

Common Data Storage Conversions

Here are quick reference conversions between the most frequently needed units.

MB to GB: Divide MB by 1,000 (decimal) or 1,024 (binary). 500 MB = 0.5 GB (decimal) or 0.488 GiB (binary).

GB to TB: Divide GB by 1,000 (decimal) or 1,024 (binary). 500 GB = 0.5 TB (decimal) or 0.488 TiB (binary).

GB to MB: Multiply GB by 1,000 (decimal) or 1,024 (binary). 2 GB = 2,000 MB (decimal) or 2,048 MiB (binary).

TB to GB: Multiply TB by 1,000 (decimal) or 1,024 (binary). 1 TB = 1,000 GB (decimal) or 1,024 GiB (binary).

Bits to Bytes: Divide bits by 8. 100 megabits = 12.5 megabytes.

For a broader range of unit conversions, see the Unit Converter.

Frequently Asked Questions

How many MB are in a GB?

In the decimal system used by drive manufacturers, 1 GB = 1,000 MB. In the binary system used by Windows, 1 GiB = 1,024 MiB. For most everyday purposes, using 1,000 is close enough. The difference is about 2.4%.

Why does my hard drive show less space than advertised?

Drive manufacturers measure capacity in decimal gigabytes (1 GB = 1,000,000,000 bytes), while Windows reports sizes in binary gibibytes (1 GiB = 1,073,741,824 bytes) but labels them as "GB." This means a 1 TB drive shows as about 931 GB in Windows. The storage is not missing; it is a labeling discrepancy between two measurement systems.

What is the difference between a bit and a byte?

A bit is a single binary digit (0 or 1). A byte consists of 8 bits. Internet speeds are measured in bits per second (Mbps), while file sizes are measured in bytes (MB). To convert between them, divide bits by 8 to get bytes, or multiply bytes by 8 to get bits.

What is the difference between MB and MiB?

MB (megabyte) in the decimal system equals 1,000,000 bytes. MiB (mebibyte) in the binary system equals 1,048,576 bytes. MiB is about 4.9% larger than MB. The IEC introduced the MiB notation in 1998 to eliminate this ambiguity, but adoption has been slow.

How many photos can I store in 1 GB?

It depends on photo resolution and format. Approximately 250 to 500 smartphone JPEG photos (at 2 to 4 MB each) fit in 1 GB. High-resolution RAW photos from a DSLR (20 to 30 MB each) would only allow about 35 to 50 photos per GB.

How do I convert internet speed (Mbps) to download speed (MB/s)?

Divide the speed in Mbps by 8 to get MB/s. A 100 Mbps connection has a theoretical maximum download speed of 12.5 MB/s. Actual speeds are typically 60% to 80% of this due to overhead and network conditions.

How many GB are in a TB?

In the decimal system, 1 TB = 1,000 GB. In the binary system, 1 TiB = 1,024 GiB. Drive manufacturers use the decimal definition, and that is what appears on product packaging.

Data unit definitions based on IEC 80000-13 and SI standards. Data accurate as of: March 2026