Why is my actual download slower than the calculator shows?

Real-world speeds are affected by network congestion, server limitations, protocol overhead (typically 5-10%), distance to server, and shared bandwidth. Actual speeds are usually 70-90% of the advertised speed.

Bandwidth Calculator

Calculate download and upload time based on file size and connection speed. Estimate how long it takes to transfer files at different bandwidths.Updated 2026-03-16

📦 File Size

⚡ Connection Speed

Estimated Download Time

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Common File Sizes Reference

File Type	Typical Size	@10 Mbps	@100 Mbps	@1 Gbps

How to Use Bandwidth Calculator

Enter the file size and select the appropriate unit (KB, MB, GB, TB).
Enter your connection speed and select the unit (Kbps, Mbps, Gbps).
The estimated download time updates automatically as you type.
Use preset buttons for common file sizes and connection speeds.

All calculations happen locally in your browser. No data is transmitted.

Frequently Asked Questions

How is download time calculated?

Download time = File Size / Speed. Note that ISP speeds are in megabits (Mb) while files are in megabytes (MB). 1 byte = 8 bits, so a 100 Mbps connection downloads at ~12.5 MB per second.

Why is my actual download slower?

Real-world speeds are affected by network congestion, server limitations, protocol overhead (5-10%), distance, and shared bandwidth. Actual speeds are usually 70-90% of advertised speed.

What is the difference between Mbps and MBps?

Mbps (megabits/sec) measures network speed; MBps (megabytes/sec) measures file transfer. 1 MBps = 8 Mbps. ISPs use Mbps, so 100 Mbps ≈ 12.5 MBps actual download rate.