What is the download speed for 100 Mbps broadband? Mbps and MB/s differ by 8 times, and the hard drive and system each have their own algorithms

Sun had just upgraded to gigabit broadband and came knocking on the door with two questions in mind. One was a speed test app running 941Mbps. After a long time on the calculator, it said no, it was over 900 Mbps per second, yet movies on the cloud drive still reached about 100 Mbps. The other was that he bought a new 2TB external hard drive to mess with photos. When he plugged it into his computer and checked the attributes, it was 1.82TB, so he immediately went to the store to confront him, suspecting he had bought an expansion drive.

I calculated both numbers for him to see. He was stunned for a long time and said, "These manufacturers are all talking about themselves." Actually, these two issues can cause a huge debate among beginner enthusiasts, and their root is the same: the unit. Broadband is a megapixel, software downloads are MB/s, and hard drives are terabytes—they look like one family, but inside are two completely different sets of conversion.

first identify the two easiest to mix in: Mbps and MB/s

in broadband ads, the unit is Mbps. Pay close attention to the lowercase 'b', which stands for bit. Download speeds displayed in software, cloud storage clients, and task manager, starting with B, Byte, Byte. One byte equals eight bits, so the plan is worth of megabytes divided by 8 to get the download speed you can see on your computer.

100 megabytes of broadband, 100÷8 = 12.5MB/s, which is the theoretical maximum, not a single cent. 500 trillion is 62.5, 1000 trillion is 125. Old Sun's 941Mbps and ÷8 run at 117MB/s. The cloud drive actually runs 110MB/s, basically near the ceiling, no tricks at all.

the actual measured wired column in the table is a slight discount compared to theory, which is a layer of protocol overhead, network cables, and device ports. Gigabit ports are physically capped at 125MB/s, and if they can stay stable between 110 and 117, that's considered healthy. I broke this down in more detail in the of the third-tier accounts: bandwidth, negotiated speed, and actual speed are three different numbers. By the way, the AX3000 mentioned on the router's detail page is 3000, which is a completely different matter from broadband megawatts. That's the advertised number calculated from the negotiated speed across several frequency bands. the article about buying routers to check specs specifically mentioned it. As for the uplink in the package, there's another ledger: gigabit broadband uplink is generally only 30 to 50 Mbps. the article about uplink and downlink asymmetry wrote about how the rules came about.

the hard drive set is a different story: old debts from the 1000 and 1024

Old Sun's 2TB drive shows 1.82TB, not because the drive has shrunk, but because two sets have been made into the crafting monster. Hard drive manufacturer trademark capacity is calculated using base-1000: 1TB equals 1000GB, and below that is 1 million MB, which is one trillion bytes. Windows statistic capacity is based on base 1024: 1KB equals 1024 bytes, multiplied layer by layer. The same 2 trillion bytes, divided by 1024 consecutively, leaves only 1862 gigabytes.

In other words, the factory trademark is about 9% less in the system. This is the price difference written in the business rules—no matter who sells, it's not like you bought a fake. To confirm whether it's an expansion drive, don't just look at the capacity numbers—copy a large file inside and read it out for verification, or use a speed test tool to run a read/write loop—the expansion disk will be exposed after just copying.

the most frustrating thing is that when this drive is plugged into the Mac, it shows 2.0TB—not a cent missing. It's not that Macs fixed the drives; it's that Apple, starting from many years ago, switched the capacity display to a 1000 base system, siding with hard drive manufacturers. Windows still counts 1024 today, but the interface is labeled with GB as the standard. In fact, the international standard for base 1024 has a special name: GiB, pronounced Gibibyte. The GB shown in Windows is actually GiB. This notation has been wrong for over twenty years and no one has planned to change it. Linux has similar pitfalls: df -h is counted as 1024, df -h as 1000. A single letter difference can cause a 9% difference on the same disk.

What kind of GB is

on a phone

phone capacity display follows Apple's method, using a 1000 base, a 128GB phone still shows around 128GB of total capacity, unlike computers where you get a 10% discount upfront. You notice your hand shrinking, but that's because the system itself takes up over ten gigabytes, not just base-based.

operators calculate data on a 1000-base scale, so 1GB equals 1 billion bytes, which is the same world as the broadband Zhao. So the cloud drive client shows 2GB of movies, but it's actually 2000MB. After downloading data, the phone's usage count is about the same. If both sides match, there's no need to count who has more.

checking data plans for payment, you can keep a clear idea: video apps target about 1GB of HD per hour, Blu-ray mode is just over 2GB, 10GB targeted packages last ten hours watching HD, and five hours of Blu-ray are used to the bottom. The elderly have a monthly 2GB number protection package, and WeChat text chats don't use up 200 Mbps a month, but when grandchildren come home and watch short videos for two nights, they reset to zero—not because carriers steal data, but because video is really unbearable by byte-level viewing.

Once you

sort out the unit, you can mentally calculate the download time

trick is simple: first divide the trillion by 8 to get MB/s. Calculate the file size by 1GB equals 1000MB, and divide by seconds to get seconds.

2GB movies, 100 Mbps bandwidth takes about 2 minutes and 40 seconds, 500 Mbps takes about 30 seconds, and gigabit is about 18 seconds. A 60GB 4K original drive, 100MB takes over two hours, gigabit takes about ten minutes—so those who use original drives end up tinkering with internal networks and NAS. I copied things from my computer to the NAS and ran a gigabit network cable at only 110MB/s. the four-way real-world test article lists both speed and slow speeds. If you really want to reach 2 gigabits, just switching to broadband isn't enough—you have to go from the optical modem port to the network cable to the network card. 2000 check every one of the four thresholds you covered. The article on which broadband to install at home and how many Mbps is enough calculated by headcount and 4K units.

there's a reverse pitfall: some people take speed test screenshots and say they get over 900 Mbps; Cloud storage membership promotion accelerates to 30 MB/s, which is MB/s. The difference between two numbers is eight times; comparing them together is like talking past a duck. When you see any speed, first glance at whether the unit is a small B or a big B; this glance can save you more than half of the arguments. Also, don't take the WiFi detail page for the 1201Mbps connection speed—that's the negotiated price between the phone and router, not a real test. the article about signal dropping frames specifically explained why it was weak.

by the way, here's a comparison of exposed age. Back then, telephone line dial-up for internet access was 56 Kbps, divided by 8 equals 7 KB/s. An MP3 player of three to four megabytes would take half a day, and the screen was full of small text in KB/s. So the older generation of netizens were actually sensitive to KB and had no concept of MB. Now, the reverse is the case: everything starts in MB/s, and KB/s only appears when downloading niche content. The unit hasn't changed; what has changed is the scale we're used to.

Why does broadband only have one conversion, but hard drives have two sets

writing this, I myself have doubts: why is broadband divided by 8 and that's enough, but hard drives have to be torn between 1000 or 1024? After some research, it all figured out: bits and bytes are counting units. Numbers themselves don't have a decimal system. If the operator says I'll give you 1000Mbps, that's 1 billion bits per second, ÷8 is a byte—one step. The problem lies in prefixes like k, m, and g—in the International System of Units, kilo is 1000, mega is 1 million, which is the old rule of weights and measures; But computer memory is naturally addressed to the power of 2, and 2 to the power of 10 equals 1024, which is very close to 1000. In the past, engineers used 1K as 1024 for convenience, and used it for decades.

Since the 1980s, the

hard drive industry has standardized capacity by 1000 bases. While others use compliant international units, Windows uses 1024 and still uses GB for statistics, which is just going along with the mistake. The most frustrating part is the memory module: the memory chips are physically made to the power of 2, so when 8GB is plugged into the computer, it shows 8GB at the right time—not a single hair missing. In the same case, memory is set to 1024, hard drive to 1000, and network to decimal—three rules squeezed into one motherboard. No wonder newbies are crazy.

U drive, SD card, and hard drive are the same number. At 1000 per unit, a 64GB storage card in a computer shows just over 59GB, which is a normal discount. If you really want to be careful about which is the industry standard and which is a bug, remember this: the standard is to see the 10% discount on the nominal price for storage, and the standard for memory is also the norm for not missing a cent on the nominal price.

three sentences to clear this account

this whole set of conversions boils down to three sentences: the transmitted megameter divided by 8 equals MB/s on the computer; Storage capacity in Windows is 9% less than the factory label claims; The GB in Windows is actually GiB, while the GB on Mac and mobile phones matches the manufacturer's trademark GB.

Old Sun summarized more sharply than I did: broadband divided by 8, hard drive discounted by 10%, the rest is just psychological effect. Later, he took a photo of the conversion table and sent it to the family group. His son replied, 'You can find this thing by searching.' Old Sun replied, 'The one found is someone else's; this one was calculated by Old Sun himself.'