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Download Time Calculator

Estimate how long a file will take to download from its size and connection speed. Supports binary or decimal sizes, Mbps/Gbps speeds, and a TCP/IP overhead.

Download time calculator

Size of the file you want to download.

ISPs quote speeds in bits per second. 100 Mbps is roughly 12.5 MB/s.

Drive vendors use decimal. Operating systems often display binary.

Accounts for TCP/IP headers and ACKs. 5% is a typical default; set to 0 to ignore.

Estimated download time

1 min 24 sec

84.21 seconds total

File size
1 GB
Line rate
100 Mbps
Effective throughput
95 Mbps (11.88 MB/s)
Overhead applied
5%

Same file on common connections

ConnectionDownload time
Dial-up (56 Kbps)1 day 17 hr 46 min
DSL (5 Mbps)28 min 4 sec
Cable (100 Mbps)1 min 24 sec
Fiber (1 Gbps)8 sec

All rows use the same file size, size convention, and protocol overhead as the inputs above.

Ideal Download Time at 100 Mbps

File sizeDecimal dataIdeal transfer time
1 GB8 gigabits80 seconds
10 GB80 gigabits13 minutes 20 seconds
100 GB800 gigabits2 hours 13 minutes 20 seconds
500 MB4 gigabits40 seconds
50 GB400 gigabits1 hour 6 minutes 40 seconds

Examples use decimal GB with 0% protocol overhead. The calculator defaults to 5% overhead, and binary GiB files take slightly longer at the same stated size.

Frequently Asked Questions about the Download Time Calculator

Why are connection speeds in bits per second but file sizes in bytes?
ISPs and network gear quote speed in bits per second by convention. File sizes are stored and shown in bytes. One byte is eight bits, so a 100 Mbps line is about 12.5 MB/s of raw throughput before any protocol overhead.
What is the difference between binary (1024) and decimal (1000) file sizes?
Drive vendors and most storage specs use decimal: 1 KB is 1,000 bytes, 1 GB is 1,000,000,000 bytes. Operating systems often display binary: 1 KiB is 1,024 bytes, 1 GiB is 1,073,741,824 bytes. A 1 GiB binary file takes about 7.4% longer to download than a 1 GB decimal file at the same speed.
Why does the calculator subtract a protocol overhead by default?
Application throughput is usually below the advertised line rate because protocols, congestion control, retransmissions, and the network path add overhead. The 5% default is only a scenario assumption. Set it to 0 for the calculator's theoretical line-rate result or enter a measured overhead for a better estimate.
Why does my real download speed look slower than this estimate?
The calculator uses your line rate, not your actual throughput. The server, your Wi-Fi link, congestion, TLS handshakes, throttling, and disk write speed can all cap the download well below your ISP rate. Try a wired connection and a fast mirror to get closer to the estimate.
Can I use this for upload time too?
Yes. Plug in your upload speed instead of download. The math is identical: bits transferred divided by effective bits per second. Just remember that residential connections often have much lower upload speeds than download.

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