Spark Plug Cross-Reference Chart
Reference common spark plug thread sizes and major-brand heat range numbering conventions.
Standard spark plug thread sizes and each major brand's heat-range numbering convention. Always match the exact part your engine manufacturer specifies — thread size alone doesn't guarantee reach or heat range compatibility.
Heat-range numbering by brand
This is the single most common source of cross-reference mistakes: the direction of the heat-range scale is not the same across brands.
About this tool
Spark Plug Cross-Reference Chart is a single-purpose utility on instant.tw, a free toolbox of calculators, converters, generators, and quick lookups. Everything works in your browser — nothing is uploaded, nothing is stored on a server unless explicitly noted.
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