Mbps vs MB/s Explained: Bandwidth, Monthly Traffic and Dedicated vs Shared Bandwidth
When you shop for a VPS or dedicated server, how fast can a "100M" plan actually download? Is "2 TB of traffic per month" enough? What is the real difference between dedicated and shared bandwidth? These questions look basic, yet they are among the most common reasons people end up with the wrong configuration. This guide clears them up with simple conversions and practical commands.
Key Takeaways
- Network bandwidth in Mbps (megabits per second) converts to download speed in MB/s (megabytes per second) by dividing by 8, so a 100 Mbps connection has a theoretical peak download speed of 12.5 MB/s.
- A 100 Mbps server running at full speed all day generates about 1.08 TB of traffic per day, or roughly 32 TB over 30 days.
- 95th percentile billing samples bandwidth every 5 minutes, discards the top 5% of the month's samples, and bills on the highest remaining value.
- Dedicated bandwidth sustains the advertised rate at any time of day, while shared bandwidth splits one uplink port among several customers and may not reach full speed during busy periods.
- IMIDC offers a range of bandwidth and routing options in Hong Kong, Taiwan, Japan, Korea, Singapore, the US and other locations, including CN2 routes back to mainland China and DDoS protection.
Who This Is For / Prerequisites
- Anyone choosing a server, or anyone who wants to check the bandwidth and traffic usage of an existing server
- The monitoring commands in this guide work on Ubuntu 22.04 / 24.04, Debian 12, Rocky Linux 9 and AlmaLinux 9
- You need SSH access to the server and sudo privileges
1. The Difference Between Mbps and MB/s
What the Units Mean
- Mbps (megabits per second): the standard unit for network bandwidth. When a provider advertises "100M" or a "1G port", this is the unit they mean. The lowercase b stands for bit.
- MB/s (megabytes per second): the speed unit shown by download managers and browsers. The uppercase B stands for byte.
The Conversion Formula
1 byte = 8 bits, so:
Theoretical maximum download speed (MB/s) = bandwidth (Mbps) ÷ 8
| Advertised bandwidth | Theoretical peak | Typical real-world speed |
|---|---|---|
| 10 Mbps | 1.25 MB/s | About 1.1–1.2 MB/s |
| 100 Mbps | 12.5 MB/s | About 11–12 MB/s |
| 1 Gbps | 125 MB/s | About 110–118 MB/s |
Real speeds are slightly lower than the theoretical figures because TCP/IP headers, encryption and similar overhead consume part of the bandwidth. Cross-border traffic is also affected by route quality, latency and packet loss.
2. How Traffic Is Calculated
Bandwidth vs Traffic
Think of bandwidth as the width of a pipe and traffic as the total amount of water that flows through it. If a server runs at full bandwidth all day, its daily traffic is:
Maximum daily traffic ≈ bandwidth (Mbps) ÷ 8 × 86,400 seconds
Taking 100 Mbps as an example: 12.5 MB/s × 86,400 ≈ 1,080,000 MB, or about 1.08 TB per day; over 30 days that is roughly 32 TB per month.
Common Billing Models
- Fixed monthly traffic: for example, a set number of TB per month, with speed throttling or extra charges once you exceed it. Check whether traffic is counted in one direction (usually outbound only, or whichever of inbound/outbound is higher) or as the combined total of both directions.
- Unmetered traffic: traffic is not counted as long as you stay within the bandwidth cap. This suits high-traffic workloads such as download sites and video, though a fair-use policy usually still applies.
- 95th percentile billing: common for high-bandwidth dedicated servers and colocation. Usage is sampled every 5 minutes; at the end of the month the samples are sorted from highest to lowest, the top 5% are discarded, and the highest remaining value becomes the billable bandwidth. This model tolerates short bursts.
For the billing model of a specific product, refer to its product page, or open a ticket to confirm with the sales team.
Estimating How Much Traffic You Need
A rough formula: Monthly traffic ≈ average page size × daily page views × 30. For example, with an average page size of 2 MB and 10,000 page views per day: 2 MB × 10,000 × 30 ≈ 600 GB per month. Sites with lots of images or video should serve static assets through a CDN to reduce origin traffic.
3. Dedicated vs Shared Bandwidth
- Dedicated bandwidth: the bandwidth is reserved exclusively for your server and can sustain the advertised rate at any time of day. It suits workloads that need stability, such as live streaming, gaming, API services and business applications.
- Shared bandwidth: several customers share the same uplink port. The advertised figure is the peak rate, and you may not reach full speed during busy periods, but the cost is lower. It suits personal blogs, test environments and lightweight workloads with fluctuating traffic.
- Port speed ≠ guaranteed bandwidth: some products are listed with a "1Gbps port". That refers to the speed of the network interface, not necessarily the bandwidth you are guaranteed. Keep the two apart when comparing plans.
Also, if your users are in mainland China, route quality often matters more than the bandwidth number. At the same 100 Mbps, an optimized route such as CN2 GIA usually delivers a noticeably better experience during evening peak hours (China time) than a standard international route.
4. Monitoring Bandwidth and Traffic on Your Server
Step 1: Install vnStat to Track Traffic
# Ubuntu / Debian
sudo apt update && sudo apt install -y vnstat
# Rocky / Alma 9 (vnStat is in the EPEL repository)
sudo dnf install -y epel-release && sudo dnf install -y vnstat
sudo systemctl enable --now vnstat
Step 2: View Traffic Statistics
vnStat needs to collect data for a while before statistics appear:
vnstat # Overview
vnstat -d # Daily statistics
vnstat -m # Monthly statistics
vnstat -l # Live rate, press Ctrl+C to exit
Step 3: View Real-Time Bandwidth Usage
# Ubuntu / Debian
sudo apt install -y iftop
# Rocky / Alma 9 (iftop is also in the EPEL repository)
sudo dnf install -y epel-release && sudo dnf install -y iftop
ip -br link # Check the interface name first, e.g. eth0, ens3
sudo iftop -i eth0 -B # -B displays rates in bytes (B/s)
iftop shows which IPs are currently using your bandwidth, which is very useful when tracking down unusual traffic.
FAQ
Why does my 100M plan only download at about 12 MB/s?
That is simply the unit conversion: 100 Mbps ÷ 8 = 12.5 MB/s, and after protocol overhead you get roughly 11–12 MB/s. It means your bandwidth is already fully utilized.
Is traffic counted inbound or outbound?
It depends on the product. Most overseas servers mainly count outbound traffic, or whichever direction is higher. Check the product description for specifics, and open a ticket if you are unsure.
What should I do if traffic suddenly spikes?
First use iftop or nethogs to identify the connections and processes consuming traffic, then check whether you are being hotlinked, abused as a proxy, or attacked. If it is a DDoS attack, consider enabling a protection service.
Is my shared bandwidth slowing down at night a server problem?
Not necessarily. It may be congestion on the shared port during busy hours, or congestion on cross-border routes during evening peak hours. Use MTR to see which hop the packet loss occurs at, then decide whether to upgrade to dedicated bandwidth or switch routes.
Summary
Remember three things: Mbps ÷ 8 = MB/s; traffic = rate × time; dedicated bandwidth is stable, shared bandwidth is economical. IMIDC offers a range of bandwidth and routing options in Hong Kong, Taiwan, Japan, Korea, Singapore, the US and other locations, including CN2 routes back to mainland China and DDoS protection. If you are not sure how much bandwidth or which billing model your workload needs, submit a ticket through the client area (available 24/7) and our technical and sales staff will advise based on your actual use case.