This download time calculator turns a file size and a connection speed into the time the transfer takes, in either direction: how long a 4.7 GB file takes to download on a 25 Mbps line (25 minutes 4 seconds), or how long a 628.8 MB video takes to upload to YouTube at 20 Mbps (4 minutes 12 seconds). Two more modes answer the questions people ask next: the speed needed to move a file in a set time (2 GB in 5 minutes needs 53.3 Mbps), and how much data a speed moves in a time window (50 Mbps for 8 hours moves 180 GB). File sizes go in as kB, MB, GB, TB or the binary MiB and GiB that Windows shows; speeds go in as kbps, Mbps, Gbps or as kB/s, MB/s and GB/s, the byte-per-second figures a download dialog shows, and the page converts between them. An optional allowance subtracts a share of the nominal speed for the packet headers and the far end's limits that every real transfer pays; the page applies none unless you pick one. Under every result sit two tables: the same file at twelve common connection speeds, and twelve common files at your speed. Everything is arithmetic in your browser; nothing is measured, and no file or address is sent anywhere.
How to use the calculator
- Choose what to work out. Time from a file size and a speed is the usual case: a game, a video export, a backup, an operating system image. Speed needed from a file size and a time tells you what connection moves the file before a deadline, which is the question a venue, a hotel or a plan upgrade asks. Data moved from a speed and a time tells you what fits in a window: an overnight backup, a month's allowance, the hour before a flight. Set Direction to upload when the file is leaving your device, so the labels and the link read correctly; the arithmetic is the same both ways.
- Enter the figures. The file size with its unit; pick MiB or GiB when the number came from Windows Explorer (a "4.38 GB" file there is 4.7 GB in decimal units). The speed with its unit: a plan and a speed test quote Mbps, a download dialog shows MB/s, and the two differ by a factor of eight. Use the figure a speed test measured in the direction you are moving the file; most home connections upload far slower than they download. The time as
1:23:45, 12:34, 90 (a plain number is minutes), 90s or 1h30m.
- Pick an allowance, or none. The arithmetic assumes every bit of the speed carries file data. A real transfer loses about 5% to packet headers before anything else (the arithmetic is in the overhead section below), and more to the far end, the Wi-Fi link and other devices on the line. The allowance takes that share off the speed before the time is worked out; the page never applies one on its own, so the default result is the arithmetic figure.
- Read the result. The three figures (time, speed, size), then the effective speed after the allowance, the time without it, the data per minute and per hour at that speed, and the two tables. Copy link to this result gives a link to this page that reopens with the same inputs.
The arithmetic
A connection speed counts bits per second; a file size counts bytes, and a byte is eight bits. So time in seconds = file size in bytes × 8 ÷ speed in bits per second. A 600 MB file on a 100 Mbps line is 600,000,000 × 8 ÷ 100,000,000 = 48 seconds. A 4.7 GB file (a single-layer DVD) at 25 Mbps is 4,700,000,000 × 8 ÷ 25,000,000 = 1,504 seconds, 25 minutes 4 seconds. A 50 GB file at 1 Gbps is 400 seconds, 6 minutes 40 seconds. With a 5% allowance the speed becomes 95 Mbps and the 600 MB file takes 50.5 seconds.
The reverse divides the other way: speed = bytes × 8 ÷ seconds. Moving 2 GB in 5 minutes needs 2,000,000,000 × 8 ÷ 300 = 53,333,333 bits per second, 53.3 Mbps, and with a 5% allowance the line has to be 56.1 Mbps. And data = speed × seconds ÷ 8: 50 Mbps for 8 hours is 50,000,000 × 28,800 ÷ 8 = 180,000,000,000 bytes, 180 GB.
Three shortcuts cover most mental arithmetic. Mbps ÷ 8 = MB/s: 100 Mbps is 12.5 MB/s, so a 100 MB file takes 8 seconds. Mbps × 0.45 = GB per hour (1,000,000 × 3,600 ÷ 8 = 450,000,000 bytes): 10 Mbps moves 4.5 GB an hour, 100 Mbps 45 GB, 1 Gbps 450 GB. And for 1 GB, 8,000 ÷ Mbps = seconds: 80 seconds at 100 Mbps, 5 minutes 20 seconds at 25 Mbps, 13 minutes 20 seconds at 10 Mbps. The same file-size arithmetic runs the other way on the video bitrate calculator, which turns a bitrate and a duration into the size of the file you are about to move.
Mbps or MB/s: the factor of eight
Internet plans, routers and speed tests quote megabits per second, written Mbps or Mb/s; browsers, download managers and file copies show megabytes per second, MB/s, and a megabyte is eight megabits. A 100 Mbps line therefore shows a download running at 12.5 MB/s at best, a 1 Gbps line at 125 MB/s, and a 25 Mbps line at 3.1 MB/s. Nothing is lost in the gap; the units differ. The calculator accepts either, so a figure read off a download dialog can be typed in as MB/s and a plan's figure as Mbps, and every result shows both.
A second unit trap sits in the file size. Storage makers, download pages, macOS and this page use decimal units: a megabyte is 1,000,000 bytes and a gigabyte 1,000,000,000. Windows Explorer divides by 1,024 instead and still writes "MB" and "GB", so it reports the binary mebibytes and gibibytes, MiB and GiB, which are 4.9% larger at the megabyte and 7.4% larger at the gigabyte: a 4.7 GB file is 4.38 GiB, and Explorer shows it as 4.38 GB. The file size field accepts MiB and GiB so a number copied from Explorer is read correctly; the time is the same either way, because the byte count is what the arithmetic converts.
Why the real transfer takes longer
The arithmetic figure is a floor. Four things stand between it and the number in the download dialog. The plan's speed is a maximum. "Up to 100 Mbps" is the line rate the provider provisions, and the speed at any moment depends on the neighbourhood, the hour and the equipment; a speed test gives the figure to type in, and a test run over Ethernet shows what the line does before the Wi-Fi link takes its share. Packet headers. A file crosses the internet in packets of at most 1,500 bytes, and each carries 20 bytes of IP header and 20 bytes of TCP header, so 1,460 of every 1,500 bytes are file data (2.7% overhead); on Ethernet each packet also carries 38 bytes of framing (preamble, header, checksum and the gap between frames), so 1,460 of every 1,538 bytes on the wire are file data, 94.9%. That is the 5% option in the allowance field; it is arithmetic, not a guess. The far end. A server sends as fast as it chooses to, and a busy mirror, a per-connection limit or a game store's own throttle is often the real ceiling; nothing on your side changes that figure, and a download manager that opens several connections is a workaround for exactly this. The Wi-Fi link. An access point's advertised rate is a link rate shared between every device on it, halved and halved again by distance, walls and a neighbour's network on the same channel; a device at the far end of a flat can see a tenth of the line's speed. Other devices on the same line, a VPN's encryption and a laptop writing to a slow disk take their shares too. The allowance field is there to apply what you measure; the page does not guess a figure for you.
Upload is the slower direction
Most home connections are asymmetric: cable, DSL and many fibre plans provision far more speed down than up, so a line that downloads at 500 Mbps may upload at 20 Mbps. The upload figure is the one that matters for sending a video to YouTube or a client, pushing a backup to a cloud drive, or a live stream, and a speed test reports it separately. A 1 GB file at 500 Mbps down and 20 Mbps up takes 16 seconds to arrive and 6 minutes 40 seconds to send. Set Direction to upload and type the upload speed; the arithmetic is identical, and the result's labels and the copied link say which direction was meant.
Uploading a video to YouTube
The file size comes first. A ten-minute 1080p export at the 8 Mbps video bitrate Google recommends, with a 384 kbps stereo track, is 8,384,000 × 600 ÷ 8 = 628,800,000 bytes, 628.8 MB; the bitrate calculator gives that figure for any bitrate and length, and a file's properties give it for an existing export. At a 20 Mbps upload speed that file takes 628,800,000 × 8 ÷ 20,000,000 = 251.5 seconds, 4 minutes 12 seconds; at 100 Mbps, 50 seconds; at 5 Mbps, 16 minutes 46 seconds. A ten-minute 2160p export at 60 fps at Google's 68 Mbps figure is 5.1 GB and takes 34 minutes at 20 Mbps. YouTube's upload cap is 256 GB or 12 hours of video, whichever is less (Google's upload limits page): a file at the cap takes 28 hours 27 minutes to send at 20 Mbps and 5 hours 41 minutes at 100 Mbps. The processing YouTube does after the upload, which produces each playback resolution, is separate work on Google's side and is not in the arithmetic. Neither is the thumbnail, which is one image under 2 MB and uploads in a moment; the thumbnail size page covers that cap.
Common files at common speeds
The arithmetic figures, with no allowance, for five file sizes at five speeds. The calculator above gives the same figure for any pair and applies an allowance if you choose one.
| File | 10 Mbps | 25 Mbps | 100 Mbps | 500 Mbps | 1 Gbps |
|---|
| 100 MB | 1 min 20 s | 32 s | 8 s | 1.6 s | 0.8 s |
| 1 GB | 13 min 20 s | 5 min 20 s | 1 min 20 s | 16 s | 8 s |
| 4.7 GB (a single-layer DVD) | 1 h 2 min 40 s | 25 min 4 s | 6 min 16 s | 1 min 15 s | 38 s |
| 25 GB (a single-layer Blu-ray) | 5 h 33 min 20 s | 2 h 13 min 20 s | 33 min 20 s | 6 min 40 s | 3 min 20 s |
| 100 GB | 22 h 13 min 20 s | 8 h 53 min 20 s | 2 h 13 min 20 s | 26 min 40 s | 13 min 20 s |
Per hour, the same speeds move 4.5 GB, 11.25 GB, 45 GB, 225 GB and 450 GB. A speed that is not in the table is a division away: time at any speed = time at 100 Mbps × 100 ÷ the speed in Mbps.
What the calculator does not do
It does not measure your connection; it has no speed test, and the figure you type is the figure it uses. It does not know the server, the store or the service at the far end, so a throttled download takes longer than its result, and a download that pauses, resumes or restarts takes longer still. It does not account for compression (a zip that unpacks after the download) or for the time a program spends installing, verifying or, in YouTube's case, processing what arrived. It does not read a file's size from a URL or from a YouTube video, and it does not start, schedule or monitor any transfer. It is the arithmetic, with the units handled and an allowance applied only when you ask for one.
Frequently asked questions
How long does it take to download 1 GB?
1 GB is 8,000,000,000 bits, so divide 8,000 by the speed in Mbps to get seconds: 13 minutes 20 seconds at 10 Mbps, 5 minutes 20 seconds at 25 Mbps, 80 seconds at 100 Mbps, 16 seconds at 500 Mbps and 8 seconds at 1 Gbps. Those are the arithmetic figures for a connection running at its nominal speed; a real download adds a few percent for packet headers and whatever the far end and the Wi-Fi link take off.
How do I convert Mbps to MB/s?
Divide by eight. A megabit per second is 1,000,000 bits a second and a megabyte is 8,000,000 bits, so 100 Mbps is 12.5 MB/s, 25 Mbps is 3.125 MB/s and 1 Gbps (1,000 Mbps) is 125 MB/s. Internet plans and speed tests quote megabits; browser download dialogs and file managers show megabytes per second, which is why a 100 Mbps line shows a download running at about 12 MB/s.
Why is my download slower than my internet speed?
Four things sit between the plan's figure and the number in the download dialog. The plan's speed is a maximum, not a guarantee, so start from a speed test, not the contract. Every 1,500-byte packet carries 40 bytes of IP and TCP headers, and Ethernet framing adds 38 more, so about 5% of the line rate never reaches the file. The far end sends as fast as it chooses, and a busy server or a single-connection limit is often the real ceiling. And a Wi-Fi link's advertised rate is shared between devices and shrinks with distance and interference. The calculator's allowance field is for the share you measure, not a guess it makes for you.
How long does it take to upload a video to YouTube?
File size × 8 ÷ upload speed. A ten-minute 1080p export at YouTube's recommended 8 Mbps plus 384 kbps audio is 628.8 MB, which takes 4 minutes 12 seconds at a 20 Mbps upload speed and 50 seconds at 100 Mbps; a ten-minute 2160p 60 fps export at 68 Mbps is 5.1 GB and takes 34 minutes at 20 Mbps. Use the upload figure from a speed test, which on most home connections is far below the download figure. YouTube's processing after the upload is separate and is not in the arithmetic.
How long does a 50 GB download take?
50 GB is 400,000,000,000 bits: 1 hour 6 minutes 40 seconds at 100 Mbps, 26 minutes 40 seconds at 250 Mbps, 13 minutes 20 seconds at 500 Mbps, 6 minutes 40 seconds at 1 Gbps and 11 hours 6 minutes 40 seconds at 10 Mbps. If the store or server throttles each download, the time follows its limit rather than your line.
How much data can I download in an hour?
Speed in Mbps × 0.45 is the GB per hour: 10 Mbps moves 4.5 GB an hour, 100 Mbps 45 GB, 1 Gbps 450 GB. Over a night of 8 hours, 50 Mbps moves 180 GB. The arithmetic is 1,000,000 bits × 3,600 seconds ÷ 8 = 450,000,000 bytes per Mbps-hour.
Why does Windows show a file as smaller than the download page says?
Windows Explorer divides by 1,024 three times and still writes GB, so it reports binary gibibytes; download pages, macOS and storage makers use decimal gigabytes of 1,000,000,000 bytes. A 4.7 GB file is 4.38 GiB and Windows shows it as 4.38 GB. The calculator accepts both: pick MiB or GiB when the figure came from Explorer, and the time is the same either way because the byte count is what it converts.
