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File Size Calculator

This calculator converts a file size between bits, bytes, and prefixed units from kilo through exa. Each step multiplies or divides by 1024 (IEC binary, KiB/MiB/GiB) or 1000 (SI decimal, KB/MB/GB), with bytes equal to bits divided by 8. Toggle the base to match OS file managers or vendor drive labels. Results update live in the browser; it does not scan disks or enforce attachment limits.

By Jeff Beem

Updated

01

File size

Enter a size and unit; results update as you type. Use binary (1024) like most OSes, or decimal (1000) for vendor and network specs.

Base
Equivalent size

1 GiB expressed as:

bits8,589,934,592
bytes1,073,741,824
kibibytes (KiB)1,048,576
mebibytes (MiB)1,024
gibibytes (GiB)1
tebibytes (TiB)0.0009765625
pebibytes (PiB)0.0000009537
exbibytes (EiB)0.0000000009

Information hub

How the math works

Binary (IEC): each step is 1024 (2¹⁰). So 1 KiB = 1024 B, 1 MiB = 1024 KiB, 1 GiB = 1024 MiB. One byte = 8 bits.

  • Using binary (1024): 1 GiB = 1024^3 = 1,073,741,824 bytes.
  • 1 × 1,073,741,824 = 1,073,741,824 bytes.
  • Total: 1,073,741,824 bytes = 8,589,934,592 bits.

Common media and storage sizes

Sizes vary by format and quality; use this as a ballpark.

3.5" floppy1.44 MB
CD (74–80 min)700 MB
DVD-R single layer4.7 GB
DVD-R dual layer8.5 GB
Blu-ray single layer25 GB
Typical MP3 song4 MB
1 min uncompressed WAV10 MB
1 hr SD video1 GB
1 hr 1080p video6 GB

How to use this calculator

Enter a size and unit in section 01, then pick binary (1024) or decimal (1000) on the Base control to match the label you are checking. The dark results card lists every equivalent unit (bits through exabytes) as you type. The How the math works panel shows multiply-by-1024 or multiply-by-1000 steps for your current input; Common media and storage sizes is a static ballpark table you can re-enter in section 01. Calculations run locally in the browser.

Reading your conversion results

The dark results card lists the same byte count in every unit. Match the Base toggle in section 01 to the source: binary (1024) for most OS file managers, decimal (1000) for drive stickers and many data caps.

Example: 1 GiB (binary default)

Defaults: base binary (1024), size 1, unit gibibytes (GiB). Results card: 1,073,741,824 bytes, 8,589,934,592 bits, 1,048,576 KiB, 1,024 MiB, 1 GiB, 0.0009765625 TiB. Step list: 1 GiB = 1024³ = 1,073,741,824 bytes; 1 × 1,073,741,824 = 1,073,741,824 bytes.

Base toggle: decimal (1000) for vendor specs

Switch Base to decimal (1000) and enter 1 gigabyte (GB). Results show 1,000,000,000 bytes, not 1,073,741,824. That ~7% gap is why a labeled "1 TB" SSD reads ~931 "GB" in Windows when the OS uses binary math with a decimal-looking label.

Bits unit in the dropdown

Pick bits when converting from network notation. Enter 800 bits → 100 bytes in the results card. A 100 Mbps line moves about 12.5 MB/s of payload (100÷8100 \div 8), not 100 MB/s. File sizes always normalize to bytes first, then scale to KB/MB/GB or KiB/MiB/GiB per your Base setting.

File size calculator: bits, bytes, and binary vs decimal

This calculator converts prefixed file-size units with 1024 or 1000 at each step and treats bytes as bits divided by 8. Results update live in the browser and do not scan disks or enforce attachment limits.

What this calculator does

Converts one file size into bits, bytes, and every larger prefix from kilo through exa. You pick binary (1024, IEC KiB/MiB/GiB) or decimal (1000, SI KB/MB/GB). All math normalizes through bytes; bits use ÷8. Calculations run locally in the browser. It does not scan disks, enforce email limits, or look up file-system maximums automatically.
  • Binary (IEC):
    1  GiB=10243=1,073,741,824  bytes1\;\text{GiB} = 1024^3 = 1{,}073{,}741{,}824\;\text{bytes}

    Used by Windows, Linux, and most file managers for on-disk sizes.

  • Decimal (SI):
    1  GB=10003=1,000,000,000  bytes1\;\text{GB} = 1000^3 = 1{,}000{,}000{,}000\;\text{bytes}

    Used on drive packaging and many network data caps.

  • Bits vs bytes:
    bytes=bits8,bits=8×bytes\text{bytes} = \frac{\text{bits}}{8}, \quad \text{bits} = 8 \times \text{bytes}

    Speeds use bits per second; file sizes use bytes.

How the math works

Every conversion first computes a byte total. For prefixed units, multiply the entered value by base^exponent (exponent 1 for kilo, 2 for mega, 3 for giga, and so on). For bits, divide by 8. The results card divides the same byte total by successive powers of the chosen base to fill every row. Example with binary defaults: 1 GiB → 1 × 1024³ = 1,073,741,824 bytes → 8,589,934,592 bits. Drive-sticker check: enter 2 TB with decimal base → 2 × 10¹² = 2,000,000,000,000 bytes → about 1,862.6 GiB when you read the gibibyte row (same bytes, different multiplier).

Limits of the model

FAT32 caps a single file at 232−12^{32}-1 bytes (4 GB minus 1 byte). NTFS and exFAT support vastly larger files in current specs. When copying huge video or disk images, confirm the destination volume allows the size you need. The static media table on this page is illustrative only; it does not change when you edit section 01. For download time from size and line speed, use the related bandwidth calculator with the same base toggle.

File Size Calculator FAQ

Why does my 1 TB drive show only about 931 GB in Windows?

Drive labels use decimal: 1 TB = 1,000,000,000,000 bytes. Windows reports in binary (1024-based) but often still prints "GB." That same byte count is 10¹² ÷ 1024³ ≈ 931.3 GiB, which Explorer may round to 931 GB. Enter 1 with unit TB and base decimal (1000), then read gibibytes in the results card to reproduce the mismatch.

What is the difference between KB and KiB in this calculator?

With base decimal (1000), the unit dropdown shows kilobytes (KB) where 1 KB = 1,000 bytes. With base binary (1024), labels switch to kibibytes (KiB) where 1 KiB = 1,024 bytes. All math normalizes through bytes before scaling to other units.

How do I convert file size from bits to bytes here?

Pick bits in the unit dropdown and enter your value. The widget divides by 8 to get bytes, then lists every larger prefix. Network speeds stay in bits per second; file sizes in the results card are always shown in bytes and prefixed byte units.

What does the Base toggle in section 01 do?

Binary (1024) matches most OS file managers (IEC KiB/MiB/GiB labels in the dropdown). Decimal (1000) matches drive packaging and many ISP data caps (SI KB/MB/GB). The multiplier applies at every step from kilo through exa.

Why 1024 instead of 1000 for "kilo" in file sizes?

Memory and addressing align to powers of two; 1024 = 2¹⁰. Standards later split SI "kilo" (1000) from IEC "kibi" (1024). This tool lets you pick either base so you can reconcile vendor stickers with OS reports.

Does the Common media and storage sizes table change with my input?

No. That panel is a static ballpark list (floppy through 1080p video). Type any row's number and unit into section 01 to convert it with your chosen base; the live results card and step list update from your entry.

What file size can I safely send by email?

Most providers cap attachments around 25–50 MB; 5–10 MB is a safe target so messages do not bounce. Convert your attachment size here, then use a cloud link if the megabyte reading exceeds your provider's cap.

What are typical file sizes for photos, video, and audio?

A 12 MP JPG is often 3–5 MB. A 3-minute MP3 might be 3–5 MB; the same clip as uncompressed WAV can be ~30 MB. SD video is roughly 1 GB/hour; 1080p often 4–8 GB/hour. Enter those values in section 01 to see exact byte counts.

Mathematical Reference Note

Calculation Logic: This tool uses standard mathematical algorithms. While we strive for accuracy, errors in logic or user input can result in incorrect data.

Verification: Results should be cross-checked if used for important academic, professional, or personal calculations.

Standard Terms: This tool is provided free of charge and as-is. CalcRegistry provides no warranty regarding the accuracy or fitness of these results for your specific needs.

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