File transfer time calculator

Estimate theoretical transfer time from file size and transfer rate.

Your inputs stay in your browser.

Method and assumptions

Method version 1.0.0 · Updated October 2, 2026

Estimate duration

Formula: Seconds = size in bytes × 8 ÷ rate in bits per second.

Theoretical estimate at a constant transfer rate.

size: File size
sizeUnit: Size unit
speed: Transfer rate
speedUnit: Rate unit

Assumes a constant rate and converts bytes to bits. Protocol overhead, congestion, network variation and processing time are excluded.

Calculate with code

These short examples use the same inputs and core calculation as this tool. Adapt validation and formatting to your application.

JavaScript

const megabytes = 100, megabitsPerSecond = 20;
const seconds = megabytes * 1_000_000 * 8 / (megabitsPerSecond * 1_000_000);
console.log(seconds); // 40 seconds (decimal MB and Mb/s)

TypeScript

const megabytes = 100, megabitsPerSecond = 20;
const seconds = megabytes * 1_000_000 * 8 / (megabitsPerSecond * 1_000_000);
console.log(seconds); // 40 seconds (decimal units)

Python

size_mb, speed_mbps = 100, 20
seconds = size_mb * 1_000_000 * 8 / (speed_mbps * 1_000_000)
print(seconds)  # 40.0 seconds

Java

double seconds = 100 * 1_000_000d * 8 / (20 * 1_000_000d);
System.out.println(seconds); // 40.0

double seconds = 100 * 1_000_000d * 8 / (20 * 1_000_000d);
Console.WriteLine(seconds); // 40