Bandwidth Calculator — File Transfer Time
Find out how long a file will take to download or upload at your connection speed — or check how fast a connection needs to be to transfer a given amount of data in a set time. Enter file size and bandwidth, and get the transfer time in seconds, minutes, or hours.
File size unit
Speed unit
1.3 min
- 1
File size in bits
1 GB × 1,000,000,000 B/unit × 8 = 8,000,000,000Network speeds use bits; multiply byte count by 8 to convert. - 2
Speed in bits per second
100 Mbps × 1,000,000 = 100,000,000 - 3
Transfer time (seconds)
8,000,000,000 ÷ 100,000,000 = 80
How does this calculator work?
Transfer time (seconds) = file_size_bytes × 8 / bandwidth_bps. A 1 GB file over 100 Mbps takes (1 × 8000 Mb) / 100 = 80 s. Remember: ISPs advertise in megabits; files are measured in megabytes — divide Mbps by 8 to get MB/s. Real-world speeds are typically 70–90% of the rated bandwidth.
Formula
How this is calculated
Network speeds are measured in bits per second (bps), while file sizes are typically quoted in bytes. One byte contains 8 bits, so a 1 GB file equals 8 Gb (gigabits). To find transfer time, convert the file size to bits and divide by the connection speed in bits per second.
For example, a 5 GB file over a 100 Mbps connection: 5 × 8000 Mbps ÷ 100 Mbps = 400 seconds ≈ 6.7 minutes. A simple rule of thumb: multiply file size in GB by 8 to get gigabits, then divide by speed in Gbps to get seconds.
This calculation assumes 100% of the advertised bandwidth is available for the transfer. In practice, network overhead (protocol headers, handshaking, congestion), other devices on the connection, and server-side throttling typically reduce effective throughput to 70–90% of the quoted speed. Add a buffer for real-world conditions. Note that ISPs advertise speeds in Mbps (megabits) while most operating systems display file sizes in MB (megabytes) — always check units to avoid confusion.
Frequently asked questions
The calculator assumes 100% utilisation of your rated bandwidth. Real-world transfers are slower due to TCP overhead, network congestion, distance to the server, shared bandwidth with other users or devices, and server upload limits. Expect 70–90% of your rated speed in practice.
Mbps (megabits per second) is how ISPs measure internet speed. MB/s (megabytes per second) is how most operating systems measure file transfer speed. Because 1 byte = 8 bits, divide Mbps by 8 to get MB/s — so a 100 Mbps connection delivers at most 12.5 MB/s.
Use a wired Ethernet connection instead of Wi-Fi, close other applications and devices using the same internet connection, choose a server or CDN close to your location, and update your network drivers. If you consistently see much less than your subscribed speed, contact your ISP.
Also known as
TG we-Calculate Editorial Team. (2026). Bandwidth Calculator — File Transfer Time [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/bandwidth-calculator
TG we-Calculate Editorial Team. "Bandwidth Calculator — File Transfer Time." TG we-Calculate. 2026. https://we-calculate.com/calculator/bandwidth-calculator.
TG we-Calculate Editorial Team, "Bandwidth Calculator — File Transfer Time," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/bandwidth-calculator
@misc{wecalculate_bandwidth_calculator, title = {Bandwidth Calculator — File Transfer Time}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/bandwidth-calculator}}, year = {2026}, note = {TG we-Calculate} }
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