File Size Calculator

This file size calculator converts between all common file size units — bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and their binary equivalents (KiB, MiB, GiB, TiB). Enter any size in any unit and the results panel shows the equivalent in every other unit across two conversion tables: decimal (SI) units used by storage manufacturers, and binary (IEC) units used by operating systems. A storage media chart shows whether the file fits on common physical media from floppy disk to 1 TB SSD.

File size conversions are more complicated than they appear because there are two competing standards in everyday use. The decimal system uses powers of 1,000: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes. The binary system uses powers of 1,024: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes. At the kilobyte scale the difference is small. At the terabyte scale it becomes significant — a "1 TB" hard drive contains 1,000,000,000,000 bytes in decimal, but your computer reports only 931 GiB because it reports in binary.

The reference comparison at the bottom of the results panel puts the file size in context. Rather than memorising conversion ratios, you can compare the file to a photo, an MP3, a video, or another familiar object. This is useful when estimating storage needs: if a project folder is 3× the size of an HD movie, it is probably around 12 GB, which is a concrete enough figure to inform a storage decision or backup plan. When file integrity matters after copying or downloading, check the file bytes with the file hash checksum calculator.

The confusion between binary and decimal file size units traces back to the early days of computing, when memory was addressed using binary counting. A kilobyte of RAM was naturally 2¹⁰ = 1,024 bytes because memory chips came in powers of two. The prefix "kilo" was borrowed from the metric system, where it means 1,000, but in the computing context it drifted to mean 1,024. For decades this was informal — no one defined it formally — and it worked fine because the difference was small and everyone in the field understood the convention.

Problems arose as storage capacities grew. At the terabyte scale, the gap between 1,000⁴ (decimal) and 1,024⁴ (binary) is about 9.5%. A hard drive marketed as "1 TB" contains 1,000,000,000,000 bytes by the manufacturer's decimal definition, but Windows reports it as approximately 931 GiB using binary reckoning. Neither figure is wrong — they use different but internally consistent definitions. The IEC formally standardised binary prefixes (KiB, MiB, GiB, TiB) in 1998 to resolve this, but adoption has been slow and informal usage of KB, MB, and GB for binary quantities persists widely.

For photographers, a typical shoot might generate 500 RAW files at 25 MB each — a total of 12.5 GB . A 64 GB memory card would hold about five similar sessions before needing to be cleared. An external 2 TB hard drive holds roughly 80,000 such files. For videographers, raw 4K footage from a cinema camera can reach 1 GB per minute, meaning an hour of footage is around 60 GB before editing. A 1 TB drive holds roughly 16 hours of this material.

For software developers and system administrators, file size awareness informs infrastructure decisions. Database backups that compress to 200 MB fit easily on a weekly rotation of 64 GB tapes. Log files that accumulate at 500 MB per day fill a 1 TB drive in about two years — a useful figure for capacity planning. Docker images typically range from 50 MB to 1 GB; a registry with 50 images might consume 25 GB of storage before considering versioned tags. These are the kinds of estimates where a quick file size conversion cuts through ambiguity and grounds the discussion in concrete numbers.

Storage labels mix decimal marketing units with binary file-system units, which is why a 1 TB drive often shows less usable space than buyers expect.

Enter the values you already know, review the headline result, then read unit breakdowns or alternate formats before sharing the answer.

Use it when comparing cloud quotas, SD card capacity, email attachment limits, backup sizes, and documentation that switches between KB, KiB, MB, and MiB.

If the result affects a deadline, storage purchase, or network upgrade, run a second version with conservative speed or size assumptions.

1 decimal GB equals 1,000,000,000 bytes, while 1 GiB equals 1,073,741,824 bytes. At terabyte scale the gap is large enough to affect backup planning and card capacity.

Change one input at a time — speed, file size, unit system, or household load — to see whether the answer is sensitive to that assumption.

The useful output is often the gap between advertised speed and measured throughput, decimal versus binary storage, or binary versus hex representation.

When explaining the result to someone else, show both the starting value and the converted outcome so the unit logic stays visible.

Check whether the source means decimal GB or binary GiB before ordering storage or setting upload limits. Operating systems, vendors, and cloud consoles do not always label units the same way.

This tool focuses on one calculation layer. It does not replace ISP contracts, storage vendor specs, calibrated instruments, or production network monitoring.

For business continuity, broadcast deadlines, or regulated data handling, confirm assumptions with measured tests and official documentation.

Treat the calculator as a fast planning check that makes unit and speed assumptions visible before you act.

This file size calculator converts between bits, bytes, decimal units such as KB, MB, GB, and TB, and binary units such as KiB, MiB, GiB, and TiB.

It fits file size calculator, bytes to MB, MB to GB, GB to GiB, file size converter, and storage media fit searches where the task is understanding a single file or amount of data.

It should not be stretched into compression estimation, image resizing, deduplication, cloud backup pricing, or storage purchase advice. Use the video bitrate file size calculator for bitrate-duration video export estimates, and the download time calculator when connection speed is part of the question.

A common workflow is to paste or enter a real sample, review the output, then adjust one setting at a time. This makes it easier to see exactly what changed and avoid copying an incorrect result.

For developer and web-design tasks, test the result in the place it will actually be used. Encoded text, CSS values, parsed URLs, timestamps, and generated strings can behave differently depending on the target system.

Check formatting, character escaping, units, timezone assumptions, and browser support before using the output in production. Small formatting differences can break code, URLs, data files, or layouts.

Avoid pasting private secrets, passwords, API keys, or personal data into tools unless you are comfortable with where that data is processed. These calculators are designed for convenient local checks, not secure secret handling.

Developer utilities are most useful when they remove a tiny but annoying source of uncertainty. Instead of writing a scratch script, opening a terminal, or guessing a format, you can check the value quickly and move back to the main task.

That matters during debugging because small mistakes often hide in plain sight: a timezone offset, a copied user agent, an invalid UUID, a malformed URL, or a random token with the wrong length.

Before using the output in production, confirm the expected length, character set, timezone, casing, browser support, and validation rules. A value that looks right in isolation can still fail a strict API, database, CSS parser, or logging pipeline.

If the output will be shared with other people, label it clearly and include the assumptions used to create it. That turns a quick utility result into something another developer can trust and reproduce.