Why does my new hard drive show less capacity than advertised?

Manufacturers use decimal (1,000) units, so 1 TB = 1,000,000,000,000 bytes. Operating systems often use binary (1,024) units, so 1 TB = 1,099,511,627,776 bytes. This difference makes the drive appear smaller in your OS.

What is the difference between decimal and binary units?

Decimal units (KB, MB, GB) are based on powers of 1,000, while binary units (KiB, MiB, GiB) are based on powers of 1,024. For example, 1 MB = 1,000,000 bytes, but 1 MiB = 1,048,576 bytes.

How do I convert between bits and bytes?

1 byte = 8 bits. To convert bits to bytes, divide by 8. To convert bytes to bits, multiply by 8. This calculator handles both directions for all units.

Conversiones

Instantáneo, privado y gratis

Conversor de Tamaño de Datos.

Convierte entre bits, bytes, KB, MB, GB, TB y PB, y entre los estándares decimal (1,000) y binario (1,024) que hacen que tu nuevo disco parezca más pequeño de lo anunciado.

Esta calculadora aún no está totalmente traducida; parte del texto se muestra en inglés.

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Which standard?

1 KB = 1,000 bytes. This is the SI standard used by hard drive and SSD manufacturers, and by most network and storage marketing.

Amount to convert

From

Como usar

KB = 1,000 bytes (SI decimal, what drive manufacturers print on the box). KiB = 1,024 bytes (IEC binary, what your operating system actually reports). The gap compounds at every step, which is why a 1 TB drive shows up as about 931 GB in Windows.

8 bits = 1 byte. Network speeds are quoted in bits per second (Mbps) while file sizes are in bytes (MB), so a 100 Mbps line downloads at roughly 12.5 MB/s at best.

RAM is always measured in binary units, and file sizes in most operating systems are too, even when the label says MB or GB.

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Cite this calculator

Canonical URL: https://mathify.one/es/conversion/data-size

Cite as: Mathify. (n.d.). Conversor de Tamaño de Datos. https://mathify.one/es/conversion/data-size

Use Cases

Check actual storage capacity

Compare advertised drive size (decimal) with the capacity shown by your OS (binary) to understand the difference.

Example: A 500 GB drive (decimal) shows as about 465 GiB in Windows.

Estimate file transfer sizes

Convert file sizes between units to estimate download times or storage needs, especially when dealing with large media files.

Example: Convert 2.5 GB to MB to see if it fits on a 4.7 GB DVD.

Frequently Asked Questions

Why does my new hard drive show less capacity than advertised?: Manufacturers use decimal (1,000) units, so 1 TB = 1,000,000,000,000 bytes. Operating systems often use binary (1,024) units, so 1 TB = 1,099,511,627,776 bytes. This difference makes the drive appear smaller in your OS.
What is the difference between decimal and binary units?: Decimal units (KB, MB, GB) are based on powers of 1,000, while binary units (KiB, MiB, GiB) are based on powers of 1,024. For example, 1 MB = 1,000,000 bytes, but 1 MiB = 1,048,576 bytes.
How do I convert between bits and bytes?: 1 byte = 8 bits. To convert bits to bytes, divide by 8. To convert bytes to bits, multiply by 8. This calculator handles both directions for all units.

Tips & Common Mistakes

Tips

Always check whether your device uses decimal or binary units to avoid confusion.
When comparing storage, use the same standard (decimal or binary) for accurate results.
Remember that 1 byte = 8 bits, so a 100 Mbps connection transfers about 12.5 MB per second.
Use binary units (KiB, MiB) when working with RAM or file systems that use 1024-based calculations.

Common Mistakes to Avoid

Assuming 1 KB = 1,024 bytes when the calculator uses decimal (1,000) by default.
Confusing bits and bytes, leading to off-by-8 errors in conversions.
Mixing decimal and binary units in the same calculation without converting.

Last updated: August 13, 2026