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File Size Converter

Convert bytes, KB, MB, GB, and TB.

Conversion ToolsUpdated 2026-04-05• Author: CalcDock Team, IT reference editor• Reviewed by: CalcDock Team, Editorial review: IEC binary vs SI decimal labeling (Apr 2026)

The File Size Converter lets you convert between all common digital storage units: bytes, kilobytes (KB), megabytes (MB), gigabytes (GB), and terabytes (TB). Choose between binary (base-2: 1 KB = 1,024 bytes) and decimal (base-10 SI: 1 KB = 1,000 bytes) calculation modes, since storage manufacturers use decimal while operating systems use binary — which is why a "1 TB" hard drive shows up as about 931 GB in Windows or macOS. Useful for understanding storage requirements, comparing device capacities, estimating upload/download times, and database storage planning.

When this calculator helps most

Use when you must align marketing TB with OS “GB,” or convert between binary and decimal conventions for a spec.

What each input means

Value — Numeric size in the selected source unit. (decimal number)
Binary vs decimal mode — 1024-based (KiB-style) vs 1000-based (SI) — must match what you are comparing. (mode)

Input mistakes to avoid

•Pick binary vs decimal mode to match the label you are reading.
•Remember 1 byte = 8 bits when comparing to Mbps.

File Size Converter

🔒Inputs are processed in your browser and are not sent to our servers.

Formula

1 KB = 1,024 bytes (binary) | 1 MB = 1,024 KB | 1 GB = 1,024 MB | 1 TB = 1,024 GB

Examples

1.5 GB to MB

Convert 1.5 gigabytes to megabytes.

→ 1,536 MB (binary) or 1,500 MB (decimal)

500 GB Hard Drive — Actual Usable Space

A 500 GB (decimal) hard drive shows how many GB in Windows?

→ 500 GB (decimal) = ~465.7 GiB (what Windows/macOS shows as "GB")

4K Video File: 40 GB to TB

A 40 GB 4K movie file in terabytes.

→ 0.039 TB (decimal) / 0.0391 TiB (binary)

How to read your results

→Manufacturers often label TB in decimal; OS file views often use binary GiB labeled “GB”.
→Network speeds are usually bits per second — multiply bytes by 8 to compare to Mbps.
→Keep extra precision before rounding when chaining conversions.

What this result means

Converted numbers clarify naming confusion — they do not change physical disk size.

Common Pitfalls

⚠️Using KB=1024 in one step and KB=1000 in another — mixed bases skew totals.
⚠️Confusing MB vs MiB labels — IEC names (KiB, MiB) reduce ambiguity.
⚠️Forgetting 8× when converting bytes to megabits for bandwidth time estimates.

Tips

✓1 photo ≈ 3–5 MB | 1 song ≈ 4–7 MB | 1 HD movie ≈ 4–8 GB | 1 4K movie ≈ 20–80 GB.
✓Use binary (1024) when checking RAM and OS reported file sizes; use decimal (1000) for hard drive specs.
✓Data transfer speeds (internet, USB) are measured in bits (lowercase b), not bytes: 1 Mbps = 0.125 MB/s.
✓Email attachment limits: Gmail/Outlook typically 25 MB. For larger files, use cloud storage links.

How to check your results

✓For decimal 1 TB → divide by 1024³ to see binary TiB approx in OS.

Warnings & Limitations

⚠️Filesystem overhead, compression, and sparse files change real footprint on disk.

What this calculator does not tell you

–Actual formatted capacity after filesystem overhead.
–Transfer time without bandwidth in consistent bits vs bytes.

Frequently Asked Questions

What is the difference between KB and KiB?

1 KB (kilobyte, SI standard) = 1,000 bytes. 1 KiB (kibibyte, IEC standard) = 1,024 bytes. Hard drives and SSDs are marketed using decimal (KB=1,000), but operating systems measure using binary (KiB=1,024). This is why a "500 GB" drive shows ~465 GB in Windows.

Why does my "1 TB" drive show less than 1 TB in Windows/macOS?

Storage manufacturers use decimal: 1 TB = 1,000,000,000,000 bytes. Operating systems use binary: 1 TB (OS) = 1,099,511,627,776 bytes. So 1 TB (decimal) = 1,000,000,000,000 ÷ 1,099,511,627,776 ≈ 0.909 TB in OS notation, which displays as approximately 931 GB.

How many MB are in a GB?

Binary: 1 GB = 1,024 MB. Decimal (SI): 1 GB = 1,000 MB. Most storage device specs use decimal; RAM, OS file sizes, and RAM use binary.

How do I calculate file transfer time?

Time (seconds) = File size (in bits) / Transfer speed (in bits per second). Note: 1 MB = 8 Mb (megabits). A 100 MB file over a 100 Mbps connection takes 100 MB × 8 / 100 Mbps = 8 seconds (ignoring overhead).

What are typical file sizes for common content?

Photo (JPEG): 2–5 MB. RAW photo: 20–40 MB. Song (MP3): 3–7 MB. HD movie (1080p): 4–8 GB. 4K movie: 20–80 GB. 1-hour Zoom recording: 500 MB–1 GB. Email attachment limit: typically 25 MB (Gmail/Outlook).

What is a terabyte in context?

1 TB can store approximately: 250,000 photos (at 4 MB each), 200,000 songs (at 5 MB each), 125 HD movies (at 8 GB each), or about 6.5 million documents (at 150 KB each). A standard Netflix 4K stream uses about 7 GB per hour.

Sources & References

Report an issue with this calculator

Editorial & review note

Labels state whether a row uses binary (1024) or decimal (1000) steps—mixing them explains most “missing gigabytes” complaints against honest disk size math.

Editorial Policy