File Size Converter

What does this file size converter do?

Digital storage is measured in a chain of units that each multiply the last: bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Every file you download, every drive you buy, and every storage plan you subscribe to gets measured in one of these units, but converting between them by hand means remembering how many times to multiply by 1024. This tool converts between all the common digital storage units instantly.

The relationship between each unit is consistent: a kilobyte is 1,024 bytes, a megabyte is 1,024 kilobytes, a gigabyte is 1,024 megabytes, and so on up the chain. That consistency makes file sizes predictable once you know the pattern, but it is still easy to lose track of a few zeros when converting a value that spans several units at once, which is exactly the kind of quick math this tool is built to handle.

How to convert file sizes online

Enter a value and choose the units you're converting between, bits, bytes, kilobytes, megabytes, gigabytes, terabytes, or petabytes, and the result updates live as you type or change units. A reference table below the calculator shows the same value across every unit at once, so you can compare them side by side without re-entering anything.

The swap button flips your from and to units in a single click, and every value recalculates the moment you change the input number or either dropdown, so there's no separate convert button to press.

Common use cases

• Checking whether a file will fit under an upload limit like the 25MB or 100MB caps used by many of the tools on this site.
• Working out how many photos, songs, or videos will fit on a drive with a given capacity.
• Converting a download size quoted in megabytes into gigabytes, or the reverse, when comparing files or plans.
• Understanding why a "1TB" hard drive shows less than 1TB of usable space in Windows or macOS.
• Estimating bandwidth or data usage when a plan or bill is quoted in a different unit than you're used to.

Tips for best results

This converter uses the binary standard, where 1 kilobyte equals 1024 bytes, the same convention operating systems like Windows and macOS use when they display a file's size in a folder or properties window. Some manufacturers and marketing materials use the decimal standard instead, where 1 kilobyte equals exactly 1000 bytes, which is why a drive advertised as "1TB" typically shows up as roughly 931GB once it's formatted and read by your operating system. The number itself isn't wrong, it's just using a different multiplier.

Why use Convert369's File Size Converter

The calculator updates instantly with no page reload, and covers every unit from a single bit up to petabytes in one place. It's free, works on any device, and is especially handy alongside the rest of Convert369's file conversion tools, since almost every one of them mentions a maximum file size, this converter is the fastest way to check whether your file fits before you even try uploading it.

Keeping a couple of rough benchmarks in mind also helps when a precise figure isn't necessary. A typical smartphone photo is a few megabytes, a high-definition movie is a few gigabytes, and a modern laptop's storage is measured in hundreds of gigabytes to a few terabytes, so a quick glance at this calculator is often enough to sanity-check whether a number you've been quoted is in the right ballpark.