Data Size Converter

Convert bytes across decimal SI and binary IEC units side by side, see transfer time at your Mbps link speed, and settle the GB vs GiB question.

Every conversion is plain arithmetic running in your browser. Nothing is uploaded or stored.

Unit
Quick picks
Decimal ladder (SI · 1000)
Binary ladder (IEC · 1024)
How long would a transfer take?
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The classic confusion: 1 GB vs 1 GiB

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How It Works

Every value is converted to a byte count first, then multiplied out into each ladder. Decimal (SI) steps multiply by 1000 — kB, MB, GB, TB, PB — while binary (IEC) steps multiply by 1024 — KiB, MiB, GiB, TiB. The bit sits at the bottom of the decimal ladder at one eighth of a byte, and results use up to six significant figures so tiny and huge values stay readable.

The 1000 vs 1024 divergence
The two ladders start equal at the byte and drift apart as you climb: 1 KiB is 1,024 bytes, 2.4 % more than 1 kB, and by the giga level the gap has widened to 7.4 % — 1 GiB = 1,073,741,824 bytes vs 1 GB = 1,000,000,000. IEC names (KiB, MiB, GiB) exist precisely so 'GB' can mean one thing: 10⁹ bytes.
Why the new drive 'shrinks'
Drive vendors market in decimal units because that is the larger, honest number: a 500 GB drive holds exactly 500,000,000,000 bytes. Older Windows versions print binary-formatted sizes but keep the decimal labels, so Explorer divides by 1024³ and calls 465.66 GiB '465.7 GB'. Same bytes, two rulers — this tool shows both readings side by side.
Transfer time: bits ÷ rate
Network speeds are quoted in megabits per second, so the tool multiplies your size by 8 to get bits, divides by rate × 10⁶, and reports seconds, minutes and hours. Remember the ÷ 8 rule of thumb: bytes-per-second throughput is about one eighth of the headline Mbps figure.

Frequently Asked Questions

Why does my 500 GB drive show as 465 in Windows?

Nothing was stolen — Windows divides by 1024-based units while the vendor label is 1000-based. 500 GB is 500,000,000,000 bytes, and 500e9 ÷ 2⁴⁰ = 465.66 GiB, which Windows still prints as 'GB'. Linux and macOS display the decimal figure, so the same drive looks the size it says on the box there.

I pay for 100 Mbps — why is my download capped near 12 MB/s?

Because the link speed is in megabits and your file size is in megabytes, and 8 bits make one byte: 100 Mbps ÷ 8 = 12.5 MB/s in the best case. Subtract protocol overhead and a shared medium and 11–12 MB/s is a healthy 100 Mbps line. The transfer row on this page does exactly that division for you.

How do mobile carriers count my data usage?

In decimal units: a carrier gigabyte is 1,000,000,000 bytes, matching how networks meter traffic, while your phone's storage readout may still use binary units. So a 5 GB plan is 5 billion bytes of streaming, not 5 × 1024³, and apps that report 'MB used' in binary can disagree with the carrier's counter by about 7 %.

Is a bit the same thing as a byte?

No — a byte is eight bits, and the capital-B convention is load-bearing: Mbps means megabits per second, MB/s means megabytes per second, and a 100 Mb file is 12.5 MB. The ladder on this page starts both lists from the bit so you can see the ÷ 8 step explicitly.

Is anything uploaded to a server?

No. Every conversion here is arithmetic on one number — powers of 1000 and 1024 — done by a few lines of vanilla JavaScript in your browser. There is no upload, no account and no network request involved.