Standard-size sink openings and faucet dimensions are used throughout the plumbing industry. However, since there are a few exceptions (such as 4" spread or 8" spread), it is a good idea to check sizes first.
Many single- and two-handle faucets are on 4-inch centers, which is the distance between the centers of the hot and cold inlets or mounting bolts. Another popular style for two-handle faucets is the 8" to 16" widespread. These faucets come with flexible hook-ups to allow for adjustments.
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The distance between hot and cold water supplies for two-handle faucets is generally 8". The hole opening for single-handle tub/shower combinations may vary. The opening must be smaller than the faceplate of the unit you are installing for proper coverage.
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