Data Transfer Guide
Mbps vs MB/s explained — understand internet speeds and why advertised speeds differ from real performance
Overview
Data transfer speed measures how fast data moves between devices or over a network. The key units are bits per second (bps) and bytes per second (B/s).
Understanding the difference between bits and bytes is crucial — internet speeds are in bits (Mbps), but file sizes are in bytes (MB).
Bits vs Bytes: The Key Difference
Bits (b)
Used for: Network speeds, internet plans
Symbol: lowercase "b" (Mbps, Gbps)
Example: "100 Mbps internet"
Bytes (B)
Used for: File sizes, storage
Symbol: uppercase "B" (MB/s, GB/s)
Example: "Download: 12.5 MB/s"
Key Formula: 8 bits = 1 byte. So 100 Mbps = 12.5 MB/s (divide by 8)
Common Data Transfer Units
| Unit | Bits per Second | Bytes per Second | Common Use |
|---|---|---|---|
| Kbps | 1,000 | 125 B/s | Old dial-up, audio streaming |
| Mbps | 1,000,000 | 125 KB/s | Home internet, mobile data |
| Gbps | 1,000,000,000 | 125 MB/s | Fiber internet, data centers |
| Tbps | 1,000,000,000,000 | 125 GB/s | Internet backbone |
Internet Speed Guide
| Speed (Mbps) | Real Download | Good For | 1 GB Download Time |
|---|---|---|---|
| 10 Mbps | 1.25 MB/s | Basic browsing, email | ~13 minutes |
| 25 Mbps | 3.1 MB/s | HD streaming, small household | ~5 minutes |
| 100 Mbps | 12.5 MB/s | 4K streaming, gaming, WFH | ~80 seconds |
| 500 Mbps | 62.5 MB/s | Large household, multiple 4K streams | ~16 seconds |
| 1 Gbps | 125 MB/s | Power users, large file transfers | ~8 seconds |
Why slower? Real-world speeds are often 10-20% lower than advertised due to overhead, network congestion, and router limitations.
Real-World Transfer Speeds
4G LTE 10-50 Mbps
5G 50-1,000 Mbps
WiFi 6 Up to 9.6 Gbps
Ethernet (Cat 6) Up to 10 Gbps
USB 3.0 5 Gbps (625 MB/s)
USB 4 / Thunderbolt 4 40 Gbps (5 GB/s)
SATA SSD ~550 MB/s (4.4 Gbps)
NVMe SSD 3,500+ MB/s (28 Gbps)
Quick Conversion Tips
Mbps → MB/s
Divide by 8
100 Mbps = 12.5 MB/s
MB/s → Mbps
Multiply by 8
10 MB/s = 80 Mbps
Download Time
File size (MB) ÷ Speed (MB/s)
= Time in seconds
Quick Estimate
100 Mbps ≈ 10 MB/s
(slightly conservative)