{
    "name": "Data Transfer Time Calculator",
    "url": "https://calculators.geekmidst.com/calculators/data-transfer-time-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/data-transfer-time-calculator.md",
    "category": "IT, networking & security",
    "description": "Work out how long it takes to transfer data of any size (kB to TB, KiB to TiB) over a link in kbps, Mbps, Gbps or MB/s, with an efficiency allowance.",
    "summary": "Transfer time = data in bits ÷ effective speed in bits per second. Sizes are in bytes and line speeds in bits, so multiply the size by 8 first.",
    "also_called": [
        "Download time calculator",
        "Upload time calculator",
        "File transfer calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "size",
            "label": "Data size",
            "type": "number",
            "default": "10"
        },
        {
            "name": "size_unit",
            "label": "Size unit",
            "type": "select",
            "default": "GB",
            "options": {
                "B": "bytes",
                "kB": "kB (1,000 bytes)",
                "MB": "MB (10⁶ bytes)",
                "GB": "GB (10⁹ bytes)",
                "TB": "TB (10¹² bytes)",
                "KiB": "KiB (1,024 bytes)",
                "MiB": "MiB (2²⁰ bytes)",
                "GiB": "GiB (2³⁰ bytes)",
                "TiB": "TiB (2⁴⁰ bytes)"
            }
        },
        {
            "name": "speed",
            "label": "Connection speed",
            "type": "number",
            "default": "100"
        },
        {
            "name": "speed_unit",
            "label": "Speed unit",
            "type": "select",
            "default": "Mbps",
            "options": {
                "kbps": "kbps (kilobits/s)",
                "Mbps": "Mbps (megabits/s)",
                "Gbps": "Gbps (gigabits/s)",
                "MBps": "MB/s (megabytes/s)",
                "MiBps": "MiB/s (mebibytes/s)"
            }
        },
        {
            "name": "efficiency",
            "label": "Efficiency",
            "type": "number",
            "default": "90",
            "unit": "%"
        }
    ],
    "outputs": [
        {
            "key": "transfer_time",
            "label": "Transfer time",
            "format": "text"
        },
        {
            "key": "transfer_seconds",
            "label": "In seconds",
            "format": "number"
        },
        {
            "key": "transfer_minutes",
            "label": "In minutes",
            "format": "number"
        },
        {
            "key": "transfer_hours",
            "label": "In hours",
            "format": "number"
        },
        {
            "key": "effective_mbps",
            "label": "Effective speed",
            "format": "number"
        }
    ],
    "formula": {
        "text": "Time (s) = Size in bytes × 8 ÷ (Speed in bits per second × Efficiency%)",
        "variables": {
            "8": "bits per byte",
            "Speed": "kbps = 10³, Mbps = 10⁶, Gbps = 10⁹ bits per second; MB/s = 8 × 10⁶ bits per second"
        }
    },
    "worked_example": {
        "inputs": {
            "size": "10",
            "size_unit": "GB",
            "speed": "100",
            "speed_unit": "Mbps",
            "efficiency": "90"
        },
        "steps": [
            "Size: 10 GB = 10 × 10⁹ bytes × 8 = 80 × 10⁹ bits.",
            "Effective speed: 100 Mbps × 90% = 90 × 10⁶ bits/s.",
            "Time: 80 × 10⁹ ÷ 90 × 10⁶ = 888.9 s ≈ 14 min 49 s."
        ],
        "result": "A 10 GB file takes about 14 minutes 49 seconds on a 100 Mbps line at 90% efficiency (13 min 20 s at the full line rate)."
    },
    "interpretation": "If a transfer of many terabytes takes days, shipping a physical disk or a provider’s offline transfer appliance may be faster. For backups, compare the result with your backup window.",
    "assumptions": [
        "The speed is sustained for the whole transfer."
    ],
    "limitations": [
        "Very high-latency links can be limited by TCP window size rather than line rate; small files add per-file overhead."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "What is the difference between Mbps and MB/s?",
            "answer": "Mbps is megabits per second; MB/s is megabytes per second. 1 MB/s = 8 Mbps, so a 100 Mbps line delivers at most 12.5 MB/s."
        },
        {
            "question": "Why does my 1 TB drive show as 931 GB?",
            "answer": "The drive maker uses decimal TB (10¹² bytes); many operating systems show binary GiB (2³⁰ bytes) labelled “GB”. 10¹² ÷ 2³⁰ ≈ 931."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Video Streaming Bandwidth Calculator",
            "url": "https://calculators.geekmidst.com/calculators/video-streaming-bandwidth-calculator"
        },
        {
            "name": "Cloud Backup Storage Cost Calculator",
            "url": "https://calculators.geekmidst.com/calculators/cloud-backup-storage-cost-calculator"
        },
        {
            "name": "Image Compression Savings Calculator",
            "url": "https://calculators.geekmidst.com/calculators/image-compression-savings-calculator"
        },
        {
            "name": "Website Bandwidth Calculator",
            "url": "https://calculators.geekmidst.com/calculators/bandwidth-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}