Data Transfer Time & Bandwidth Calculator
Calculate file download and upload duration across broadband, 5G, and fibre speeds with real-world TCP/IP overhead and transfer speed comparisons.
Transfer Parameters
Transfer Rate & Data Volume Breakdown
Duration Across Other Connection Speeds
About this tool
How to use it
- Enter the total file or backup payload size and choose the unit (MB, GB, TB, or PB).
- Enter your network connection speed and select the unit (Mbps, Gbps, MB/s, or GB/s).
- Select your real-world protocol efficiency (default 90% accounts for TCP headers and TLS handshakes).
- Review the estimated duration, real net throughput in MB/s, and compare times across standard ISP speed tiers.
Why it matters
Internet providers advertise bandwidth in megabits per second (Mbps), while file sizes and storage drives are measured in megabytes (MB) or gigabytes (GB). Because 1 byte equals 8 bits and real-world TCP/IP packet framing adds 5% to 15% protocol overhead, dividing file size directly by advertised speed produces inaccurate estimates. This calculator gives realistic transfer durations.
When to use it
Use when downloading large game installs, uploading 4K video footage to client cloud drives, sizing off-site disaster recovery backup windows, or estimating database migration times across VPN tunnels.
Good to know
Calculations convert data into bits ($1\text{ Byte} = 8\text{ bits}$) and apply configurable TCP/IP transport overhead factors. Actual transfer speeds may also be limited by disk I/O write bottlenecks and remote server rate limits.
Common questions
Why is download speed in MB/s so much lower than Mbps?
Broadband providers advertise bandwidth in Megabits per second (Mbps, with a lowercase 'b'), whereas files are measured in MegaBytes (MB, with an uppercase 'B'). Because 8 bits equal 1 byte, a 100 Mbps connection delivers a theoretical maximum of 12.5 MB/s, which drops to around 11.25 MB/s after accounting for protocol overhead.
How long does it take to download a 50 GB game on a 100 Mbps connection?
On a 100 Mbps internet connection with realistic 90% TCP efficiency (11.25 MB/s effective throughput), a 50 GB game takes approximately 1 hour, 14 minutes, and 5 seconds to download.
What causes the difference between advertised speed and real download time?
Packet framing, TCP acknowledgment packets, SSL/TLS cryptographic handshakes, Wi-Fi radio interference, and remote server bandwidth throttling all introduce real-world transmission overhead (typically 10% to 20%).
How long does a 1 TB backup take over Gigabit internet?
A 1 TB (1,000 GB) backup over a 1 Gbps (1,000 Mbps) connection with 90% network efficiency (112.5 MB/s actual throughput) takes approximately 2 hours, 28 minutes, and 9 seconds.
Is upload speed the same as download speed?
On symmetrical fiber connections, upload and download speeds are equal. However, on standard cable and DSL broadband, upload speeds are often restricted to 10% to 20% of download speeds (e.g. 200 Mbps download with only 10 Mbps upload), making file uploads take significantly longer.