Internet Speed Calculator
Calculate file download time from your internet speed. Convert between Mbps, MB/s, Gbps, KB/s, and other speed units.
Quick Answer
Download time = File Size / Speed. A 1 GB file at 100 Mbps takes about 80 seconds (1 GB = 8 Gb, 8000 Mb / 100 Mbps = 80s). Remember: 1 byte = 8 bits.
Download Time Calculator
Results
1m 22s
Estimated Download Time
100 Mbps
Speed in Mbps
12.5 MB/s
Speed in MB/s
12,800 KB/s
Speed in KB/s
1,024 MB
File Size in MB
About the Internet Speed Calculator
This tool calculates how long it takes to download or upload a file based on your internet connection speed. It also converts between common speed units. Internet speeds are typically measured in Mbps (megabits per second), while file sizes are in MB or GB (megabytes or gigabytes). The difference between bits and bytes causes frequent confusion for consumers comparing advertised speeds to actual download performance.
Bits vs Bytes
There are 8 bits in 1 byte. Internet speeds are measured in bits (Mbps = megabits per second), while files are measured in bytes (MB = megabytes). To convert: 100 Mbps = 12.5 MB/s. This means a 100 Mbps connection downloads at about 12.5 megabytes per second. ISPs advertise in bits because the numbers are 8 times larger and sound more impressive. When your download manager shows 12.5 MB/s on a 100 Mbps plan, your connection is actually running at full speed.
Real vs Advertised Speed
Your actual download speed is typically 60-90% of the advertised speed due to network overhead, congestion, server limitations, and protocol overhead (TCP headers, routing, etc.). WiFi connections are slower and less consistent than wired Ethernet. Running a speed test at speedtest.net or fast.com gives you a more realistic number to use in calculations. Also, download speeds are usually faster than upload speeds on most cable and DSL connections.
Speed Unit Conversions
The most common conversions: 1 Gbps = 1000 Mbps. 1 Mbps = 0.125 MB/s (divide by 8). 1 MB/s = 1024 KB/s. 1 Gbps = 125 MB/s. These conversions help you understand what your internet plan actually delivers in practical file transfer speeds. A gigabit fiber connection at 1 Gbps transfers files at up to 125 MB/s, which means a 1 GB file downloads in about 8 seconds under ideal conditions.
What Affects Download Speed
Several factors affect real-world download speed: server capacity (the source may limit your speed), network congestion during peak hours, WiFi interference and distance from router, VPN overhead, and your device's processing capability. Using wired Ethernet, downloading during off-peak hours, and connecting to nearby servers all help maximize your actual speed. For large downloads, pause other bandwidth-heavy activities to get the best performance.