How to use (3 steps)
- Choose what to solve: transfer time (size + speed), transfer speed (size + time), or data size (speed + time).
- Enter the two known values with units. Turn on the efficiency factor if you want to account for overhead (e.g., 80%).
- Results update automatically with conversions. Use “Copy URL” to share exactly the same scenario.
Seconds in the display are rounded up; sizes and speeds are rounded to 2 decimals.
Inputs
Fill in any two fields (data size, transfer speed, transfer time). Keep units consistent with your entry: b = bit, B = byte (1B = 8b). Decimal (GB) and binary (GiB) units are both supported.
Result
Transfer time result
Estimated transfer time
1B = 8b. Decimal units use powers of 1000; binary units use powers of 1024.
How it’s calculated
- Formula: data size = transfer speed × time. When solving for speed or time, we just rearrange this equation.
- All inputs are converted to bits and seconds internally. Decimal units (GB) and binary units (GiB) are handled separately.
- If efficiency is on, effective speed = nominal speed × efficiency%. Use this to estimate protocol overhead or real-world loss.
- Seconds are rounded up for HH:MM:SS. Sizes and speeds are rounded to 2 decimals in the display.
- Real-world speeds fluctuate. Treat the output as an estimate, not a guarantee.
FAQ
How do you handle bits vs bytes and GB vs GiB?
We convert everything to bits (b) and seconds, then back to your chosen units. 1 byte = 8 bits. GB/MB use 1000 steps, while GiB/MiB use 1024.
What does the efficiency factor change?
When enabled, effective speed = nominal speed × efficiency%. Lower efficiency increases the estimated time or required speed. Leave it off to treat your input speed as fully usable.
Can I enter time as HH:MM:SS?
Yes. Choose the split field option for hours, minutes, and seconds, or use a single total time with seconds, minutes, hours, or days. Displayed seconds are always rounded up.
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