Download Time Calculator: File Size ÷ Connection Speed
Enter a file size and your connection speed to see how long the download will take. Speed can be in bits (Mbps, Gbps) or bytes (MB/s), and a real-world speed factor accounts for the gap between your plan speed and what you actually get. Use it to estimate game updates, video files, or backup transfers. Everything is calculated in your browser, and nothing you type is sent to a server. For unit math, try the Unit Converter; to shrink images first, try the Image Resizer & Compressor.
🔒 Runs in your browser · Your data is never sent to a server
Your plan speed is a theoretical maximum; congestion and equipment usually lower it. 50-80% is typical. Enter 100 to calculate at the full plan speed.
Notes
- File sizes use decimal units (1 KB = 1,000 bytes). Some operating systems show 1 KB as 1,024 bytes, so the size they display can differ slightly.
- Bits per second (bps) are 8 times bytes per second (B/s). A 100 Mbps connection tops out around 12.5 MB/s.
- Real download times depend on congestion, Wi-Fi signal, server-side limits, and protocol overhead. Treat the result as an estimate.
Glossary
bps vs. B/s
Connection speeds are usually quoted in bits per second (bps), while file sizes are in bytes (B). One byte is 8 bits, so 100 Mbps is at most about 12.5 MB/s.
Effective speed
The speed you actually get. Plan speeds are theoretical maximums, and congestion, equipment, and protocol overhead usually bring the real figure lower.
Throughput
The amount of data actually transferred per second over a link. It is what determines download time, and it is often lower than the advertised bandwidth.
FAQ
How is the download time calculated?
The file size is converted to bits (1 byte = 8 bits) and divided by your connection speed multiplied by the real-world speed factor. For example, 1 GB over 100 Mbps at 100% is 8,000 megabits ÷ 100 Mbps = 80 seconds.
What is the difference between Mbps and MB/s?
Mbps is megabits per second and MB/s is megabytes per second, and 1 MB/s = 8 Mbps. Internet plans are quoted in Mbps or Gbps while download dialogs often show MB/s, so convert to the same unit before comparing.
What real-world speed percentage should I use?
Around 80-90% suits a wired connection with little congestion, and 50-70% is typical for Wi-Fi or busy evening hours. If you know your measured speed, enter it as the connection speed and set the percentage to 100.
Why might the file size shown on my system look different?
This tool uses decimal units (1 KB = 1,000 bytes), while some systems show 1 KB as 1,024 bytes (KiB, MiB). The gap is about 2.4% at KB scale and about 7% at GB scale, which is usually fine for an estimate.
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