Network & IT · Data transfer planning
Calculate download or file transfer time from data size and transfer speed. You can also solve for required bandwidth or the amount of data moved over a duration.
Mathematical transfer estimate only. Actual transfer time can differ because of network, protocol, storage, and remote-system conditions this calculator does not measure.
Download Time solves data size plus transfer speed for an estimated duration. Required Bandwidth solves data size plus a target duration for the needed line rate. Data Transferred solves rate plus duration for the amount moved.
The core relationship is data = rate × time. The calculator rearranges that same relationship for the selected mode and normalizes every unit before solving.
Lowercase b means bit and uppercase B means byte. One byte is eight bits, so 100 Mbps is exactly 12.5 MB/s before any efficiency assumption.
GB uses decimal powers of 1,000, while GiB uses binary powers of 1,024. One GiB is 1,073,741,824 bytes, so the selected unit can materially change a transfer-time result.
Efficiency is a user-controlled modeling assumption. The default 100% represents the mathematical line-rate limit; the app does not claim a universal real-world overhead percentage.
1 GB at 100 Mbps takes 80 seconds. Moving 100 GB in 10 minutes requires about 1.33333 Gbps at 100% efficiency. A 100 Mbps rate sustained for one hour moves 45 GB.
This calculator does not measure speed, congestion, latency, packet loss, protocol overhead, retransmissions, Wi-Fi conditions, or ISP performance. Real transfers can take longer than the mathematical estimate.
Use the calculator for downloads or uploads when you know the relevant size and rate. Use the Mbps vs MB/s guide when a service quotes bits per second but a file application displays bytes per second.
