None (Theoretical Speed)
5% (Low Overhead)
10% (Typical TCP/IP)
20% (Heavy Congestion/WiFi)
Real-world transfers are rarely 100% efficient due to headers and latency.
Estimated Transfer Time
00:00:00
Effective Speed:– Total Data Transferred:–
Understanding File Transfer Rates
Whether you are uploading a video to YouTube, downloading a AAA game title, or migrating a server database, understanding how long a file transfer will take is essential for planning. This calculator helps you estimate the time required based on your file size and network speed, accounting for real-world protocol overhead.
The Difference Between Bits (b) and Bytes (B)
The most common source of confusion in file transfers is the difference between storage units and transmission units.
Storage (File Size) is typically measured in Bytes (e.g., Megabytes MB, Gigabytes GB). Note the capital 'B'.
Speed (Bandwidth) is typically measured in bits per second (e.g., Megabits per second Mbps, Gigabits per second Gbps). Note the lowercase 'b'.
There are 8 bits in 1 Byte. This means if you have a 100 Mbps internet connection, your theoretical maximum download speed is actually 12.5 MB/s (100 divided by 8).
Common Connection Speeds Reference
Connection Type
Advertised Speed (Bits)
Max Transfer Rate (Bytes)
USB 2.0
480 Mbps
~60 MB/s
USB 3.0
5 Gbps
~625 MB/s
Ethernet (Fast)
100 Mbps
12.5 MB/s
Ethernet (Gigabit)
1000 Mbps (1 Gbps)
125 MB/s
Wi-Fi 5 (802.11ac)
Up to 1300 Mbps
~162 MB/s (Theoretical)
4G LTE
~50 Mbps
~6.25 MB/s
5G
100+ Mbps to 10 Gbps
12.5 MB/s to 1.25 GB/s
Why Is My Transfer Slower Than Calculated?
In the real world, you rarely achieve the theoretical maximum speed calculated by simple division. Several factors slow down transfers:
Protocol Overhead: Every packet of data sent over the internet includes "headers" (address information) which takes up bandwidth but isn't part of your file. TCP/IP usually adds about 5-10% overhead.
Network Congestion: If many users are on the same network node, available bandwidth is split.
Disk I/O: Sometimes your internet is faster than your hard drive can write the data, especially with older mechanical HDDs versus modern NVMe SSDs.
Server Limiting: The server you are downloading from might cap the speed per user to ensure stability for everyone.