Download Time Calculator: MB, GB, GiB and Mbps
Estimate file transfer time with decimal or binary file units, bits or bytes per second, and an explicit usable-throughput assumption.
Your inputs
Choose units carefully: Mbps and MB/s differ by a factor of eight. The throughput percentage is your assumption.
Your result
Enter your values, then choose Calculate.
Calculated from your inputs and the assumptions below. Displayed results are rounded; inputs are not sent to a calculation server.
Calculation breakdown
Method, assumptions and worked example
Time in seconds = file bytes × 8 ÷ [speed in bits per second × usable-throughput fraction]. One byte contains eight bits. Mbps means megabits per second; MB/s means megabytes per second.
Decimal and binary units
GB uses 1,000,000,000 bytes; GiB uses 1,073,741,824 bytes. Similarly, MB uses 1,000,000 bytes and MiB uses 1,048,576. The former blanket statement “1 GB = 1024 MB” has been removed. If an application labels a binary quantity as GB, choose the binary unit matching the actual byte count.
Worked example
A 10 GB file at 100 Mbps needs 800 seconds, or 13 minutes 20 seconds, at ideal full throughput. At an entered usable-throughput factor of 80%, it needs 1,000 seconds: 16 minutes 40 seconds. A 10 GiB file is larger and takes about 858.99 seconds even at ideal 100 Mbps.
Use a realistic speed assumption
The 80% example is an adjustable scenario, not a universal network-overhead rate. If you enter a measured sustained file-transfer speed, set usable throughput to 100% to avoid discounting it twice. Server speed, Wi-Fi conditions, competing traffic, pauses, setup and decompression can change elapsed time.
This also estimates upload transfer time when you enter the upload speed. It does not run a connection test or fetch a file. A zero-byte file has zero modeled transfer time; fixed setup time is excluded. Positive subsecond transfers are labeled rather than rounded down to zero.
Frequently asked questions
What is the difference between Mbps and MB/s?
Mbps counts millions of bits per second; MB/s counts millions of bytes. With eight bits per byte, 100 Mbps equals 12.5 MB/s before throughput adjustments.
Does the 80% default represent every connection?
No. It is an example assumption. Use 100% for a measured sustained payload rate or choose a factor appropriate to your planning scenario.
Method review and references
Formula and content reviewed on 10 October 2026. Worked examples are hypothetical. Conversion definitions and calculation assumptions are stated below. Carrier and campaign terms must be supplied by you.