Enter the file size with its unit and the connection speed with its unit. File sizes are in bytes, and speeds are in bits per second, so the calculator converts one to the other: a byte is 8 bits. Decimal units use 1,000 and binary units such as mebibytes use 1,024.
Use your measured speed from a speed test rather than the advertised plan speed, since real throughput is usually lower.
Estimated transfer time from file size
| File size | 5 |
|---|---|
| File size unit | Megabytes (MB, decimal) |
| Connection speed | 100 |
| Speed unit | Megabits per second (Mbps) |
| Estimated transfer time | 0.4 seconds |
| Total data size (megabits) | 40 |
Download Time: formula
The estimate divides payload bits by sustained throughput. Connection setup, protocol traffic, shared bandwidth and the sending server can lengthen a transfer; there is no universal overhead percentage.
Common error: Treating the advertised connection speed as the sustained real-world rate. Network overhead, shared bandwidth, wireless signal strength and the server's own upload speed routinely bring the real transfer rate well below the number printed on a plan.
Download Time: changing File size
| File size | Estimated transfer time | Total data size (megabits) |
|---|---|---|
| 4 | 0.3 seconds | 32 |
| 4.5 | 0.4 seconds | 36 |
| 5 (example) | 0.4 seconds | 40 |
| 5.5 | 0.4 seconds | 44 |
| 6 | 0.5 seconds | 48 |
Download Time: compare input ranges
| Input | Tested from | To | Total data size (megabits): low input | Total data size (megabits): high input | Swing |
|---|---|---|---|---|---|
| File size unit | Megabytes (MB, decimal) | Gibibytes (GiB, binary) | 40 | 42,949.7 | 42,909.7 (107274%) |
| File size | 4.5 | 5.5 | 36 | 44 | 8 (20%) |
| Connection speed | 90 | 110 | 40 | 40 | 0 |
Download Time: individual input comparisons
| Input | Value | Estimated transfer time | Total data size (megabits) |
|---|---|---|---|
| File size | 4 | 0.3 seconds | 32 |
| 4.5 | 0.4 seconds | 36 | |
| 5 | 0.4 seconds | 40 | |
| 5.5 | 0.4 seconds | 44 | |
| 6 | 0.5 seconds | 48 | |
| File size unit | Megabytes (MB, decimal) | 0.4 seconds | 40 |
| Mebibytes (MiB, binary) | 0.4 seconds | 41.9 | |
| Gigabytes (GB, decimal) | 6.7 minutes | 40,000 | |
| Gibibytes (GiB, binary) | 7.2 minutes | 42,949.7 | |
| Connection speed | 80 | 0.5 seconds | 40 |
| 90 | 0.4 seconds | 40 | |
| 100 | 0.4 seconds | 40 | |
| 110 | 0.4 seconds | 40 | |
| 120 | 0.3 seconds | 40 | |
| Speed unit | Kilobits per second (Kbps) | 6.7 minutes | 40 |
| Megabits per second (Mbps) | 0.4 seconds | 40 | |
| Gigabits per second (Gbps) | 0.0 seconds | 40 |
Estimated transfer time: File size against Connection speed
| File size / Connection speed | 80 | 100 | 120 |
|---|---|---|---|
| 4 | 0.4 seconds | 0.3 seconds | 0.3 seconds |
| 4.5 | 0.5 seconds | 0.4 seconds | 0.3 seconds |
| 5 | 0.5 seconds | 0.4 seconds | 0.3 seconds |
| 5.5 | 0.6 seconds | 0.4 seconds | 0.4 seconds |
| 6 | 0.6 seconds | 0.5 seconds | 0.4 seconds |
Download Time: values and definitions
| Quantity and definition | Value used |
|---|---|
| File size — Size of the file to transfer. | 5 |
| File size unit — Decimal units (MB, GB) use powers of 1000; binary units (MiB, GiB) use powers of 1024. | Megabytes (MB, decimal) |
| Connection speed — Your connection's rated speed, as advertised. | 100 |
| Speed unit — Internet speeds are always advertised in decimal bits per second. | Megabits per second (Mbps) |
| Estimated transfer time | 0.4 seconds |
| Total data size (megabits) | 40 |
A connection's advertised speed is quoted in bits per second while a file's size is shown in bytes, and a byte is 8 bits, so the two numbers cannot be divided directly without converting one to match the other first: skipping that step is the single most common reason a calculated transfer time comes out roughly 8 times too favorable.
Confirm which unit your file-size figure and your speed figure are in before comparing them; an operating system reporting file size in binary GiB against an ISP advertising speed in decimal Gbps introduces a second, smaller unit mismatch on top of the bits-versus-bytes one.
Estimate monthly data use on the bandwidth calculator, convert sizes on the storage converter and look at network sizing on the subnet calculator. The password entropy and aspect ratio pages cover other tech topics, and the speed, distance and time calculator handles the same relation for travel.
Why is my download slower than my plan speed?
Plans are quoted in bits per second at best, and real transfers lose speed to overhead, Wi-Fi quality, server limits and other devices sharing the line.
How do I convert megabits to megabytes?
Divide by 8, since a byte has 8 bits, so a 100 megabit connection moves at most 12.5 megabytes per second.
What is the difference between MB and MiB?
A megabyte is 1,000,000 bytes and a mebibyte is 1,048,576 bytes, so binary units run about 5% larger at that size.