Bandwidth Calculator
Calculate how long it takes to transfer a file at a given internet speed. Supports all file size and bandwidth units.
Transfer Time
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File Size (MB)
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Speed (Mbps)
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What is Bandwidth Calculator?
A bandwidth calculator tells you how long it will take to transfer a file given your internet connection speed. It converts between different file size units (bytes to terabytes) and bandwidth units (Kbps to Gbps) to give you an accurate transfer time estimate.
How to use
- 1 Enter the file size and select its unit (B, KB, MB, GB, or TB).
- 2 Enter your connection bandwidth and select its unit (Kbps, Mbps, or Gbps).
- 3 Click Calculate to get the transfer time.
- 4 Note that real-world speeds are often 60–80% of advertised bandwidth due to overhead.
- 5 Use the result to plan large uploads or downloads.
Formula
Example calculation
A 1 GB file (8,589,934,592 bits) at 100 Mbps (100,000,000 bps) takes 8,589,934,592 / 100,000,000 = 85.9 seconds, or about 1 minute 26 seconds.
Frequently asked questions
Why is my actual download slower than the calculator shows?
Advertised speeds are theoretical maximums. Real-world factors like network congestion, server speed, Wi-Fi interference, and protocol overhead reduce actual throughput to 60–80% of the rated speed.
What is the difference between Mbps and MB/s?
Mbps (megabits per second) is used for network speeds. MB/s (megabytes per second) is used for file sizes. 1 MB/s = 8 Mbps. ISPs advertise in Mbps; file transfers show MB/s.
How do I find my actual internet speed?
Run a speed test at fast.com or speedtest.net. Use the download speed result as your bandwidth input for more realistic estimates.
Does the calculator use binary or decimal units?
This calculator uses decimal units (1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes), consistent with how storage manufacturers and ISPs measure sizes and speeds.
How long to upload a 4K video?
A 1-hour 4K video is roughly 45 GB. At 10 Mbps upload speed, that's about 10 hours. At 100 Mbps, about 1 hour.