Download Time Calculator
Calculate file download time for any connection speed.
Enter file size and internet speed to get the estimated download time in seconds, minutes, or hours.
Download time depends on two things: how big the file is (in bytes) and how fast the connection transfers data (in bits per second). The conversion between them is the source of most confusion.
Internet speeds are measured in bits per second. File sizes are measured in bytes. There are 8 bits in 1 byte.
Time (seconds) = (File Size in bytes x 8) / Speed in bits per second
A 500 MB file at 100 Mbps: File = 500 x 1,000,000 bytes = 500,000,000 bytes Speed = 100,000,000 bits per second Time = (500,000,000 x 8) / 100,000,000 = 40 seconds
This calculator uses decimal prefixes (1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes), which is how internet service providers and storage manufacturers report their numbers. Operating systems may display file sizes in binary (1 MB = 1,048,576 bytes), which can make a downloaded 500 MB file appear as 476 MB in Windows Explorer.
Real-world downloads rarely achieve the theoretical maximum. Overhead from TCP/IP headers, network congestion, server throttling, and Wi-Fi interference typically reduce actual throughput to 60-80% of the advertised speed. This calculator shows the theoretical minimum — actual download time will be somewhat longer.
Speed context for 2025:
- 25 Mbps: FCC minimum definition of broadband. A 4K streaming film (15 GB compressed) takes about 80 minutes.
- 100 Mbps: Common fiber tier. That same film: 20 minutes.
- 1 Gbps (1000 Mbps): High-end fiber. Same film: under 2 minutes.
- Mobile 5G peak: 1-4 Gbps theoretical, but 100-300 Mbps in practice.