What's the difference between MB and MiB?

A megabyte (MB) is 10^6 bytes — that's 1,000,000 — under the decimal SI convention. A mebibyte (MiB) is 2^20 bytes — that's 1,048,576 — under the binary IEC convention. The gap is about 5% at the MB level and roughly 7% at GB scale. Both notations show up in the wild depending on the audience, so the tool reports both whenever you do a conversion.

Why are HDD sizes 'smaller' than advertised?

Drive manufacturers count in decimal — a 1 TB drive really does hold exactly 10^12 bytes, or 1,000,000,000,000. Most operating systems report in binary, where 1 TiB is 2^40 bytes, or about 1,099,511,627,776. So the same physical drive shows up on the box as 1.0 TB and in your file manager as roughly 909 GiB. Neither number is wrong, they're just different conventions, and the gap is exactly the 7% you'd expect at this scale.

What's the difference between Mb and MB?

Lowercase 'b' is bits, uppercase 'B' is bytes, and a byte is eight bits. So 1 Mb (megabit) is one million bits, while 1 MB (megabyte) is one million bytes, or eight million bits. Internet bandwidth is almost always quoted in megabits per second while file sizes are in megabytes, which is why a 100 Mbps connection actually downloads at about 12.5 MB/s. The case of the letter genuinely matters here.

How do I estimate file sizes?

Some rough mental anchors that come up constantly — a typed document runs 10 to 100 KB, a phone photo is 1 to 5 MB, an MP3 is 5 to 10 MB, a video is anywhere from 50 MB to several GB depending on length and quality, an OS install lands between 10 and 50 GB, a modern AAA game ships at 30 to 100 GB, and a Blu-ray movie file sits around 25 to 50 GB. The tool just makes the unit conversions painless once you have a number to work with.

What about Tebi, Gibi, and Mebi prefixes?

Those are the IEC binary prefixes — KiB (kibibyte), MiB (mebibyte), GiB (gibibyte), TiB (tebibyte) — and they always use a 1024 multiplier. The IEC introduced them precisely to disambiguate from the SI decimal prefixes that look almost identical. You'll see them in technical specifications, programming references, and operating system displays, though marketing departments tend to avoid them because the numbers look smaller.

Can I convert between bandwidth and time?

Some implementations include a 'how long will this take' calculator. The math is GB times 8 times 1000 divided by Mbps to get seconds, so a 10 GB file over a 100 Mbps line works out to roughly 800 seconds, or about 13 minutes. It's the kind of quick check that's useful for download estimates, planning a large video transfer, or sizing a backup window.

Is the data sent anywhere?

No, the conversion is just arithmetic running in JavaScript inside your browser. Whatever file sizes or bandwidth numbers you punch in stay entirely on your machine, which is reassuring when the values themselves happen to be sensitive — internal traffic figures, capacity plans, and the like.

Data Size Converter

Convert between bytes, KB, MB, GB, and TB online. Free data size converter for storage and bandwidth calculations with precision.

Calculators Unit Converters

Instant results

Enter value to convert

Conversions

Bytes

1073741824B

Kilobytes

1048576KB

Megabytes

1024MB

Gigabytes

1GB

Terabytes

0.000976563TB

Petabytes

9.53674e-7PB

Bits

8589934592bit

Kilobits

8589934.592Kbit

Megabits

8589.934592Mbit

Gigabits

8.589935Gbit

How to Use Data Size Converter

Enter a value with its unit

Type the number you're converting and choose the unit it's in — B, KB, MB, GB, TB, and so on. For bandwidth conversions you'll typically reach for Kbps, Mbps, or Gbps; for file sizes and storage capacity, KB, MB, and GB are the workhorses.

View conversions

The result appears in every common unit at once, with both the decimal SI version (KB, MB) and the binary IEC version (KiB, MiB) shown side by side. Seeing them next to each other makes the gap between the two conventions obvious, which is exactly the moment you're most likely to need the distinction.

Switch between bytes and bits

Flip the toggle between byte units (used for file sizes) and bit units (used for bandwidth). One byte is eight bits, which is the factor that trips up the comparison between a 100 Mbps internet connection and a 1 GB file. The toggle keeps that distinction front of mind so you don't accidentally divide or multiply when you should have done the opposite.

Use the result

Drop the converted value wherever you need it — capacity planning, file size estimates, bandwidth math, or transfer time calculations. Pick decimal or binary based on the context. Hard drive specs, network speeds, and cloud capacity quotes use decimal, while operating systems and most programming references use binary, so the right choice depends on which side of that fence your work sits on.

When to Use Data Size Converter

File size estimation

Switching between bytes, KB, MB, GB, and TB sounds trivial until you're comparing video codecs at 3am or trying to fit a backup onto an 8 GB drive. Capacity planning, evaluating file formats, and estimating how long a download will take all start with getting the units right.

Network bandwidth analysis

Bandwidth gets quoted in megabits per second while file sizes are in megabytes, and that factor of eight trips up everyone the first dozen times. A 100 Mbps connection is roughly 12.5 MB/s, which is why your gigabit fiber doesn't actually move a 1 GB game in one second. Spelling out the bit versus byte distinction makes ISP comparisons and streaming bitrate math feel less like guesswork.

Storage planning

How many photos, MP3s, or hours of 4K video fit on a 1 TB drive? The exact answer depends on bitrate and format, but the conversion math is the easy part. This is the quick check you do before clicking buy on a new SSD, picking a cloud storage tier, or sizing a backup target.

Programming and databases

Schema design hits this constantly. VARCHAR(255) is roughly 255 bytes per row, buffer allocations need byte counts, and embedded systems treat every kilobyte like rent. Quick conversions help when you're estimating how a row count translates into actual disk pressure or memory use.

Data Size Converter Examples

MB to GB

Input

5000 MB

Output

≈ 4.88 GB (decimal). Or 4.88 GiB (binary).

A common conversion that gets messier than it should. Going from MB to GB means dividing by 1000 in decimal or 1024 in binary, so 5000 / 1024 lands at 4.88 GiB. At this scale the gap between the two conventions is about 7%, which is exactly why your 5 TB drive feels short.

Bandwidth conversion

Input

100 Mbps

Output

= 12.5 MB/s. = 100,000,000 bits/sec. = 12,500,000 bytes/sec.

Internet speeds are in bits, file sizes are in bytes, so divide by 8 to translate. A 100 Mbps connection actually moves 12.5 MB/s, meaning a 1 GB file takes around 80 seconds even when nothing else is contending for the link.

Decimal vs binary KB

Input

1 KB (decimal) vs 1 KiB (binary)

Output

1 KB = 1000 bytes. 1 KiB = 1024 bytes. Difference grows: 1 GB = 10^9, 1 GiB = 2^30 ≈ 7% larger.

There are two standards in play. SI uses powers of 1000 and IEC uses powers of 1024, and the gap widens as the units grow. Drive manufacturers prefer the decimal numbers because they look larger on the box, while operating systems usually report binary, which is exactly why a 1 TB drive shows up as roughly 909 GB once it's mounted.

Tips & Best Practices for Data Size Converter

1.Be explicit about whether you mean 1000 or 1024 byte multiples. KB and KiB look almost identical but differ by 2.4% per step, and that compounds at higher units. HDD ads use decimal, Windows reports binary, and ambiguity here causes real arguments.
2.A byte is 8 bits, and bandwidth almost always uses bits while files use bytes. Marketing departments lean on this confusion, so write out Mbps versus MBps explicitly when it matters and double-check the case.
3.Rough mental anchors help — a typed document runs around 10 KB, a phone photo sits near 3 MB, an MP3 is roughly 5 MB, a feature-length 1080p movie file is somewhere between 4 and 8 GB, an OS install hovers around 10 GB, and a current AAA game ships at 50 GB or more.
4.When buying storage, check formatted versus advertised capacity. A 1 TB drive holds exactly 1,000,000,000,000 bytes by the manufacturer's count, which the OS reports as roughly 931 GiB after formatting. Losing about 7% to that conversion is normal, not a defect.
5.Cloud storage tiers usually quote decimal capacity, so a 1 TB plan really means 10^12 bytes of usable space. Verify the convention in the provider's docs before you push close to the limit, because some clients display binary numbers that make it look like you have more headroom than you do.
6.Memory and storage don't follow the same convention. RAM is sold and reported in binary (so 4 GB of RAM is genuinely 4 GiB), while drives are sold in decimal. Operating systems sometimes silently convert between the two, which is why the same number can mean different things in different parts of the system info panel.

Frequently Asked Questions

All the standard byte sizes from B through KB, MB, GB, TB, and into PB, with both the decimal SI convention (1 KB equals 1,000 bytes) and the binary IEC convention (1 KiB equals 1,024 bytes) shown side by side. Bit-based units like Kb, Mb, and Gb are in there too, which is what you actually want when you're comparing internet bandwidth quotes against file sizes.

Data Size Converter

How to Use Data Size Converter

Enter a value with its unit

View conversions

Switch between bytes and bits

Use the result

When to Use Data Size Converter

File size estimation

Network bandwidth analysis

Storage planning

Programming and databases

Data Size Converter Examples

MB to GB

Bandwidth conversion

Decimal vs binary KB

Tips & Best Practices for Data Size Converter

Frequently Asked Questions

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