Metric Glance by cach_dies

Converts non-metric units to metric inline on every page as you read. Hover or tap any conversion to see the original, switch units, or correct a mistake. Configurable units, rounding, and formatting. Free and open source.

Experimental

Available on Firefox for Android™

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About this extension

Browser extension that converts imperial units to metric inline, for the 95% of the world on metric and the scientific minds in the other 5% who'd rather be.

Converts as you read: lengths, weights, volumes, areas, temperature, speed, and dimension lists (like 4 x 3 x 1 in). Converted values get a dotted underline; hover (desktop) or tap (mobile) to see the original, switch between similar units (the three fluid ounces, US vs imperial gallon, ounce vs troy ounce, and so on), or mark a mistake.

🔍 Missed something? Select the text and open the searchable unit picker from the right-click menu or the keyboard shortcut (Ctrl+Alt+M, Cmd+Alt+M on Mac). Remappable in Firefox's Manage Extension Shortcuts.

💰 Rounds awkward prices: $1.99 becomes $2. You set the threshold — how many cents a price may be nudged up before it rounds, so $1.99 can round while $1.50 stays put.

🔓 Free and open source. On first install a welcome page lets you choose whether to share anonymized training examples to help improve detection. You can change this anytime in Preferences.

Developer comments

This extension is in active development. The current detection engine is a deterministic regex, functional but not context-aware. The optional data sharing feature collects anonymized training examples to train a small and lightweight token-classification model that will eventually replace the regex. Once enough labeled examples are gathered the model will be trained and shipped as an update.

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Metric Glance by cach_dies

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