Bandwidth Calculator
Convert between bandwidth units like Mbps, Gbps, MB/s and estimate download times. Includes a common file sizes reference table.
About Bandwidth Calculator
Internet speeds are measured in bits per second (Mbps), but file sizes are measured in bytes (MB). This difference confuses many people - a 100 Mbps connection downloads at 12.5 MB/s, not 100 MB/s. This calculator converts between all common bandwidth units and estimates download times for different file sizes at your connection speed. All calculations run in your browser.
Bits vs Bytes - The Key Difference
One byte equals 8 bits. ISPs advertise speeds in bits per second (using a lowercase 'b'), while operating systems show file sizes and download speeds in bytes (uppercase 'B'). This 8x difference is the most common source of confusion.
| Unit | Symbol | Equals | Used By |
|---|---|---|---|
| Kilobits per second | Kbps | 1,000 bits/s | Legacy connections, audio streaming |
| Megabits per second | Mbps | 1,000 Kbps | ISP plans, speed tests, WiFi specs |
| Gigabits per second | Gbps | 1,000 Mbps | Ethernet, fibre, data centre links |
| Kilobytes per second | KB/s | 8 Kbps | Slow download progress bars |
| Megabytes per second | MB/s | 8 Mbps | File downloads, disk throughput |
| Gigabytes per second | GB/s | 8 Gbps | SSD benchmarks, memory bandwidth |
When your ISP sells you a "100 Mbps" plan, your maximum download speed in your browser or file manager is 100 / 8 = 12.5 MB/s. In practice, overhead reduces this to roughly 11-12 MB/s.
Download Time Estimates
The calculator shows estimated download times for common file sizes at your chosen speed.
| File Type | Typical Size | At 50 Mbps | At 100 Mbps | At 1 Gbps |
|---|---|---|---|---|
| Email (text) | 50 KB | Instant | Instant | Instant |
| MP3 song | 5 MB | 0.8 sec | 0.4 sec | 0.04 sec |
| Photo (high-res) | 15 MB | 2.4 sec | 1.2 sec | 0.12 sec |
| HD movie (1080p) | 4 GB | 10.7 min | 5.3 min | 32 sec |
| 4K movie | 15 GB | 40 min | 20 min | 2 min |
| Game download | 80 GB | 3.6 hours | 1.8 hours | 10.7 min |
| Full backup | 256 GB | 11.4 hours | 5.7 hours | 34 min |
These are theoretical best-case times. Real-world downloads are typically 10-30% slower due to protocol overhead (TCP headers, encryption), server-side speed limits, network congestion, and WiFi signal quality.
Common Internet Connection Speeds
| Connection Type | Typical Download Speed | Typical Upload Speed |
|---|---|---|
| 3G mobile | 1-5 Mbps | 0.5-2 Mbps |
| 4G LTE mobile | 20-100 Mbps | 5-30 Mbps |
| 5G mobile | 100-1000 Mbps | 50-200 Mbps |
| ADSL broadband | 5-24 Mbps | 1-3 Mbps |
| Cable broadband | 50-500 Mbps | 5-50 Mbps |
| FTTP fibre | 100-1000 Mbps | 100-1000 Mbps |
| WiFi 5 (802.11ac) | Up to 3.5 Gbps (theoretical) | Same |
| WiFi 6 (802.11ax) | Up to 9.6 Gbps (theoretical) | Same |
| Ethernet (Cat 5e) | 1 Gbps | 1 Gbps |
| Ethernet (Cat 6a) | 10 Gbps | 10 Gbps |
SI Units vs Binary Units
Networking uses SI (base-10) prefixes where 1 Megabit = 1,000,000 bits. Storage sometimes uses binary (base-2) prefixes where 1 Mebibyte (MiB) = 1,048,576 bytes. This tool uses SI units, which is the standard for bandwidth.
| SI (Networking) | Value | Binary (Storage) | Value |
|---|---|---|---|
| 1 KB | 1,000 bytes | 1 KiB | 1,024 bytes |
| 1 MB | 1,000,000 bytes | 1 MiB | 1,048,576 bytes |
| 1 GB | 1,000,000,000 bytes | 1 GiB | 1,073,741,824 bytes |
| 1 TB | 1,000,000,000,000 bytes | 1 TiB | 1,099,511,627,776 bytes |
This is why a "500 GB" hard drive shows as roughly 465 GiB in your operating system. The drive manufacturer uses SI (500 x 10^9 bytes), while your OS reports in binary (dividing by 1024^3).
Bandwidth Requirements for Streaming
| Service | Quality | Recommended Speed |
|---|---|---|
| Netflix | SD (480p) | 3 Mbps |
| Netflix | HD (1080p) | 5 Mbps |
| Netflix | 4K Ultra HD | 25 Mbps |
| YouTube | 4K | 20 Mbps |
| Zoom video call | HD (1080p) | 3.8 Mbps up + down |
| Online gaming | Varies | 3-10 Mbps (latency matters more than bandwidth) |
| Spotify audio | High quality | 0.32 Mbps (320 Kbps) |
These are per-stream requirements. A household with 4 simultaneous HD streams needs at least 20 Mbps of actual throughput.
For converting between number bases used in networking, try the Number Base Converter. For binary and decimal conversions, the Binary to Decimal Converter is focused on that use case. All calculations run in your browser.
Frequently Asked Questions
What is the difference between Mbps and MBps?
Mbps (megabits per second) is used by ISPs to advertise internet speeds. MBps (megabytes per second) is what your operating system shows for file downloads. There are 8 bits in a byte, so 100 Mbps equals 12.5 MBps.
How accurate is the download time estimate?
The estimates show the theoretical best case based on your chosen speed. Real-world downloads are typically slower due to network overhead, server limits, routing, and congestion. Expect actual times to be 10-30% longer.
What bandwidth units does this tool support?
It supports bps, Kbps, Mbps, Gbps, Tbps for bits per second, and B/s, KB/s, MB/s, GB/s for bytes per second. All conversions use SI (base-10) units as is standard for networking.
Why do ISPs use bits instead of bytes?
Networking has historically used bits because data travels over wires one bit at a time. Using bits also produces larger numbers, which can make connection speeds sound faster in marketing materials.
What internet speed do I need for streaming?
For HD (1080p) streaming, about 5-10 Mbps is sufficient. For 4K streaming, you need 25 Mbps or more per stream. Video calls typically need 3-5 Mbps upload and download.
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