Bandwidth Calculator
Bandwidth Is Measured in Bits, Files Are Measured in Bytes
Internet plans are advertised in megabits per second (Mbps), but the file sizes shown on your computer are in megabytes (MB) — and there are 8 bits in a byte. That factor of 8 is the single most common source of confusion when someone expects a "100 Mbps" connection to download a 100 MB file in one second, when it actually takes closer to eight. This calculator handles the unit conversion and computes transfer time or required bandwidth directly, so the bits-vs-bytes gap doesn't have to be done by hand.
The Formula
All three modes reduce bandwidth and file size to a common unit before comparing them:
Required Bandwidth (bps) = File Size (bits) / Time (s)
File size is converted using the 1024-based storage convention (1 MB = 1024² bytes), while bandwidth uses the 1000-based network convention (1 Mbps = 1,000,000 bps) — matching how ISPs advertise speed and how operating systems report file size.
Where This Calculation Matters
- Judging an internet plan — converting an advertised Mbps figure into an actual expected download time for a specific file or game update.
- Video call and streaming planning — comparing available bandwidth against the required bitrate for a given call quality or stream resolution.
- Backup and migration windows — working out the required bandwidth to move a dataset of known size within a fixed maintenance window.
- Network capacity planning — sizing a link so it can support target transfer times for the busiest expected files.
Time to Transfer a 1 GB File
| Connection Speed | Transfer Time |
|---|---|
| 10 Mbps | 14.32 min |
| 25 Mbps | 5.73 min |
| 100 Mbps | 1.43 min |
| 300 Mbps | 28.63 sec |
| 1000 Mbps (1 Gbps) | 8.59 sec |
Real-world transfer speed is almost always lower than the advertised connection speed due to protocol overhead, server-side limits, and network congestion.
How to Use This Calculator
- Choose a calculation type: Convert Bandwidth Units, Transfer Time from Bandwidth, or Required Bandwidth from Time.
- For unit conversion, enter a Value and choose the From and To units (bps through Tbps).
- For transfer time, enter File Size with its unit and Bandwidth with its unit.
- For required bandwidth, enter File Size and the target Time (seconds).
- Select Calculate to see the result.
Related Calculations
Estimating a single download rather than sizing a connection? Use the Download Time Calculator. To project how much data a connection consumes over a month, see the Bandwidth Usage Calculator.