UnoffIChO
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I built UnoffIChO as a way to practise chemistry calculations in a queue or on a train, without scratch paper or a calculator.

Yijun Wang · IChO 2026 gold (UK team) · IOAI 2026 bronze

Interactive practice for A-Level, C3L6, UKChO and IChO.

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Guides by competition

A-Level Chemistry calculationsCambridge Chemistry Challenge (C3L6)UK Chemistry Olympiad Round 1UK Chemistry Olympiad Round 2International Chemistry Olympiad (IChO)

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Your progress stays on this device. No accounts, no tracking. About UnoffIChO

Unofficial and independent. Not affiliated with the International Chemistry Olympiad, the Royal Society of Chemistry, the University of Cambridge or any exam board.