Cloud & Networking

Data Transfer Time Calculator

Work out how long a transfer will take for a given size and connection speed.

By TheCalcTools Updated Formula checked and tested

Your numbers

Real transfers lose some capacity to protocol overhead and congestion. 85–95% is typical on a clean link.

Your results

Transfer time
Transfer time
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Hours
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Effective throughput (MB/s)
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Data Transfer Time Calculator by TheCalcTools

How the Data Transfer Time Calculator works

Enter the amount of data and its unit, then the line speed and its unit.

Data sizes use decimal units (1 GB = 10⁹ bytes) and speeds are in bits per second, so the calculator multiplies the size by 8.

Dividing by the effective speed gives the time in seconds.

The formula

time = size × 8 ÷ (speed × efficiency)

Worked example

Using the default values shown in the calculator:

Data size100
Size unitGB
Link speed1
Speed unitGbps
Efficiency (%)90
  1. 100 GB = 800 gigabits.
  2. At 1 Gbps and 90% efficiency the effective speed is 0.9 Gbps, so the time is 800 ÷ 0.9 = 888.9 seconds.
  3. That is 0h 14m 48.9s, or 0.25 hours.

Result:

Transfer time0h 14m 48.9s
Hours0.25
Effective throughput (MB/s)112.50

Frequently asked questions

Why is a 1 Gbps link not 1 GB per second?

Link speeds are in bits per second and a byte is 8 bits, so 1 Gbps moves at most 125 MB per second before overhead.

What efficiency should I use?

About 90–95% on a wired LAN or a dedicated link, and lower on Wi-Fi, shared or long-distance connections.

Sources and further reading

Bandwidth-Delay Product CalculatorFind how much data is in flight on a link, and the TCP window needed to fill it Data Rate Converter (Mbps, MB/s, Gbps)Convert a data rate between bits-per-second and bytes-per-second units Bandwidth Needed CalculatorConvert monthly data volume into the line speed you need

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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.