Download Time Calculator — File Size ÷ Connection Speed
Calculate how long a download takes from file size and connection speed (Mbps/Gbps), with bits-vs-bytes handled correctly and common speed presets.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
At other speeds
Real-world speeds are usually lower than your plan’s maximum — expect roughly 50–80% of the advertised rate. Sizes use decimal units (1 MB = 10⁶ bytes); speeds are in bits per second, so 100 Mbps ≈ 12.5 MB/s.
About this tool
How long will that 50 GB game or 4 GB video actually take to download? Enter the file size and your connection speed, and this calculator gives you a realistic time estimate. It handles the classic trap automatically: internet plans are sold in megabits per second (Mbps), while file sizes are shown in megabytes (MB) — a factor of eight apart. You can also apply an efficiency factor to reflect real-world speeds. Everything is computed locally in your browser, so nothing about your connection or files is uploaded.
Frequently asked questions
Why is my 100 Mbps plan not downloading at 100 MB/s?
Because bits and bytes are different units. Internet speeds are measured in megabits per second (Mbps), but file sizes and download managers use megabytes (MB), and one byte is eight bits. Divide by eight: a 100 Mbps connection tops out at about 12.5 MB/s. This tool does that conversion for you, so the estimate you see already accounts for the factor that catches most people out.
Why are my real downloads slower than the calculator predicts?
The advertised speed is a best-case ceiling, not a promise. Protocol overhead from TCP/IP eats a few percent, Wi-Fi loses more to distance, walls and interference, and the server on the other end may throttle each connection or simply be busy. Other devices and apps on your network share the same pipe, too. As a rule of thumb, plan for 80–90% of the rated speed on a wired connection and often less over Wi-Fi.
Does this tool test my connection or send any data?
No. It is a pure calculator: it takes the file size and speed you type in and does the arithmetic locally in your browser, without running a speed test or contacting any server. Nothing about your connection, plan or files is uploaded or logged. If you do not know your actual speed, run a separate speed test first, then enter the measured value here for a more accurate estimate.