Sparkpond CalcFlow

Technical calculations, clearly explained.

Calculate file sizes, transfer times, ratios, pixel dimensions, dates and units directly in your browser.

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File Transfer Time Network & data · Estimate upload or download time from file size, transfer speed and efficiency. See exact unit conversions, formula and assumptions.
Required Transfer Speed Network & data · Calculate the bandwidth required to move a file within a target duration, including an efficiency allowance.
Data Rate Converter Network & data · Convert network data rates between bits and bytes per second with a complete unit table.
Storage Unit Converter Network & data · Convert decimal and binary storage units without mixing GB and GiB.
Bitrate, Size & Duration Network & data · Calculate media file size, average bitrate or duration from the other two values.
Aspect Ratio Calculator Image & screen · Simplify image or screen dimensions into an aspect ratio and compare common formats.

● Runs in your browser · No account required

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Popular calculators

Estimate upload or download time from file size, transfer speed and efficiency. See exact unit conversions, formula and assumptions.

Simplify image or screen dimensions into an aspect ratio and compare common formats.

Calculate new pixel dimensions by width, height, percentage or maximum box while preserving aspect ratio.

Convert network data rates between bits and bytes per second with a complete unit table.

Calculate calendar days and weeks between ISO dates without daylight-saving errors.

Convert image pixel dimensions to print dimensions in inches, centimetres and millimetres.

Transfer time, bandwidth, bitrate and unambiguous digital units.

Ratios, resizing, pixel density, print dimensions and CSS lengths.

Simplify ratios and solve proportions with visible steps.

Elapsed time and timezone-safe calendar arithmetic.

Units remain explicit, from GB versus GiB to Mbps versus MB/s.

The calculation runs locally, without an account or business API.

Formula, substitution, assumptions and version accompany every answer.

Local by design

Exact values are not required by the server. Sharing is voluntary and keeps state in the URL fragment.