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データ転送時間計算機

開発者数学ネットワーキング

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入力

自動処理

出力

クライアント側

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ガイド

データ転送時間計算機

Instantly calculate how long it will take to transfer a file over any network connection. Enter your file size and bandwidth, adjust for protocol overhead and real-world network efficiency, and get the precise transfer time in days, hours, minutes, or seconds.

使い方

Enter your file size (B, KB, MB, GB, TB, or PB) and your available bandwidth (bps, Kbps, Mbps, or Gbps). Select the protocol overhead for your connection type, set the network efficiency percentage, then hit 計算 to see the result instantly. Use the preset buttons for quick common scenarios.

特徴

6 file size units – B, KB, MB, GB, TB, PB
4 bandwidth units – bps, Kbps, Mbps, Gbps
Protocol overhead – TCP (~95%), UDP (~98%), HTTP (~90%), or none
Network efficiency slider – 50–100%, default 80% for real-world conditions
Auto-formatted output – shows days, hours, minutes, and seconds
Quick presets – 1 GB over 100 Mbps, 4K movie over 5G, 1 TB backup over 500 Mbps
Effective speed display – shows actual throughput after overhead and efficiency

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 よくある質問

Why does my actual transfer take longer than the calculated time?

The calculator accounts for protocol overhead and network efficiency, but real-world transfers are also affected by disk read/write speeds, server processing time, network congestion, and background processes competing for bandwidth. The efficiency slider (default 80%) accounts for most of these variables.
What is protocol overhead and why does it affect transfer speed?

Protocol overhead is the extra data that network protocols add to ensure reliable delivery. TCP adds acknowledgement packets and error-checking data (~5% overhead), HTTP adds request headers and keep-alive traffic (~10% overhead), while UDP is leaner with only ~2% overhead. This overhead reduces the effective throughput available for your actual file payload.
How is transfer time calculated mathematically?

The formula is: Time (seconds) = (File size in bytes x 8) / (Bandwidth in bps x Protocol efficiency x Network efficiency). The file size is multiplied by 8 to convert bytes to bits, since network bandwidth is measured in bits per second.
What is the difference between Mbps and MBps?

Mbps (megabits per second) is the standard unit for network speeds as advertised by ISPs, while MBps (megabytes per second) describes file sizes and storage speeds. Since there are 8 bits in a byte, a 100 Mbps connection delivers roughly 12.5 MBps of actual file throughput before accounting for overhead.