Bandwidth Calculator – File Transfer Time & Speed
Calculate file transfer time from file size and connection speed, or the speed needed for a target time. Supports KB to TB sizes, kbps to Gbps, SI units.
Transfer time
00:01:23
83.89 seconds
In minutes
1.4
0.02 hours
Data size
100 MB
0.1 GB
Effective speed
10 Mbps
Assumes 1 MB = 1,024 KB, 1 Mbps = 1,000,000 bits/s
Real-world transfer also depends on server limits, latency and network congestion.
Last updated: June 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
A bandwidth calculator answers practical questions about downloads, uploads and connection planning. Students and remote workers use it to estimate how long software installers, video files and online courses take to download on their home connections. Video editors uploading large projects use it to plan their upload windows. IT administrators use it to size office internet links, calculating whether a 100 Mbps line can handle nightly backups of a few gigabytes. Cloud users estimate sync times for photo libraries, gamers check how long game updates take, and streamers estimate upload needs for their broadcasts. Network planners use the required-speed mode to choose between broadband plans by working backward from a deadline. With MB, GB and TB sizes, Mbps and Gbps speeds, and both forward and reverse calculations, the tool covers everything from a quick download check to capacity planning.
How to Use This Calculator
- Step 1: Choose transfer time or required speed, then pick the unit convention — Classic counts 1 MB as 1,024 KB, SI counts 1 MB as 1,000 KB.
- Step 2: Enter the file size and select its unit: KB, MB, GB or TB.
- Step 3: For transfer time, enter the connection speed in kbps, Mbps, Gbps or MB/s; for required speed, enter the target time in seconds.
- Step 4: Read the transfer time in hours, minutes and seconds, or the required speed in Mbps and Gbps.
Worked Example
A 100 MB video on a 10 Mbps connection transfers in 83.89 seconds (00:01:23) under Classic units, or exactly 80 seconds under SI. A 200 GB backup over 100 Mbps takes about 4 hours 46 minutes, and 1 TB over 1 Gbps about 2 hours 27 minutes. As a rule of thumb, a 100 Mbps line moves about 12.5 MB per second. The required-speed mode works backwards — moving 100 MB in 60 seconds needs about 13.98 Mbps, useful for choosing a broadband plan around a real deadline.
Tips and Common Mistakes
- •Tip 1: There are 8 bits in every byte, so a 100 Mbps connection moves roughly 12.5 MB per second.
- •Tip 2: Use SI units when comparing with drive and file-system sizes that use 1,000-based prefixes.
- •Tip 3: Use the required-speed mode to size a broadband plan around a real deadline, like a backup window.
- ✗Mistake 1: Confusing MB (data size) with Mbps (speed) — a 100 MB file and a 100 Mbps connection are different quantities.
- ✗Mistake 2: Expecting real downloads to match the estimate exactly — server limits, Wi-Fi interference and congestion slow things down.
Frequently Asked Questions
How is download time calculated?
File size is converted to bits, then divided by the connection speed. For example, 100 MB at 10 Mbps takes about 83.9 seconds because 100 MB holds about 838.9 million bits.
Why is there a difference between MB and Mbps?
MB (megabytes) measures data size, while Mbps (megabits per second) measures transfer speed. There are 8 bits in a byte, so a 100 Mbps connection moves about 12.5 MB per second.
Does this calculator use 1000 or 1024 for megabytes?
Storage sizes here use 1 MB = 1,024 KB, which is how files are counted on most devices, while speeds use the standard 1 Mbps = 1,000,000 bits per second.
What does "required speed" mode tell me?
It works backwards: given a file size and a target time, it tells you the connection speed needed. This is useful when planning uploads or choosing a broadband plan.
Why might real downloads take longer?
Actual speeds are limited by the server you are downloading from, Wi-Fi signal strength, network congestion and latency, so real transfer times are often longer than the estimate.
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