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Data Size Converter

Convert between bytes, KB, MB, GB and TB in seconds.

Processed locally — nothing is uploaded

About Everyday Converters

Each of the three has a trap. Roman numerals carry no zero and no place value, a kilobyte means 1,000 or 1,024 bytes depending on who is counting, and fuel economy inverts between the two systems — a higher MPG is better while a higher L/100km is worse.

Convert data sizes between bytes, KB, MB, GB and TB using 1024-based steps — useful for sizing files, downloads and storage quotas. The conversion runs locally in your browser.

Convert numbers to and from Roman numerals, change data sizes between bytes, kilobytes, megabytes, gigabytes and beyond, and translate fuel economy across MPG, L/100km and km/L. It bundles three common conversions you reach for surprisingly often.

Everything works offline in your browser. Decode a Roman numeral on a monument, size a file or download, or compare a car's fuel efficiency between regional standards in seconds.

Learn how this works

Everyday Calculations & Conversions Made SimpleConvert units and time zones, and calculate age, BMI, discounts and loan EMIs — a plain-English guide with free in-browser tools.7 min read

Frequently asked questions

Is a kilobyte 1,000 or 1,024 bytes?

Both, depending on who is counting. Storage manufacturers use 1,000 (the SI definition), while operating systems have traditionally used 1,024. That difference is why a '1 TB' drive shows as about 931 GB in Windows.

What are KiB, MiB and GiB?

The unambiguous binary units: a KiB is exactly 1,024 bytes, a MiB 1,024 KiB. They exist precisely to remove the confusion above, and are worth using in technical documentation.

What is the difference between a megabit and a megabyte?

Eight to one. Internet speeds are quoted in megabits per second while file sizes are in megabytes, so a 100 Mbps connection downloads at about 12.5 MB/s at best — the single most common source of 'my internet is slower than advertised'.

Common Use Cases

  • •Working out why a drive shows less capacity than advertised
  • •Converting a download speed into a realistic transfer time
  • •Checking whether a file fits a storage or upload quota

More Everyday Converters tools

Everyday ConvertersRoman Numeral Converter

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