Data Size & Transfer Time Calculator

No. It calculates from the speed you enter. It does not contact a test server or measure your current connection.

One byte contains eight bits. A 100 Mbit/s connection is ideally 12.5 MB/s. Choose the exact unit displayed by your connection plan or transfer app.

GB uses 1,000,000,000 bytes. GiB uses 1,073,741,824 bytes. Decimal prefixes use powers of 1,000; binary prefixes use powers of 1,024.

It is a planning assumption for the usable fraction of the entered speed. 85% uses 85% of that speed. It is not a measured protocol overhead or a prediction about a particular service. 100% gives the ideal lower bound.

Their sizes are added and the estimated transfers are sequential at the entered effective speed. This is not a model of simultaneous downloads competing for bandwidth.

It is the advertised rate required to transfer the total amount within the target duration at the same chosen efficiency. Real systems may still be limited by the server, storage or other factors.

Input accepts up to 12 whole digits and six decimal places without commas or exponents. Size arithmetic uses integer fractions; displayed conversions round to six decimals, or nine for bytes. Time estimates use floating-point arithmetic and round up to whole seconds when at least one second. Small times and rounded small conversions are labeled explicitly.

Zero file size gives zero time. Connection speed and target duration must be greater than zero. Efficiency is 1–100% and copies are 1–1,000. Fractional bytes are flagged because actual file lengths use whole bytes.

Only numbers are needed. Calculation and report generation run locally without processing upload or saved history. Website ads and analytics follow the privacy information.