Work out at a glance how much concentrate and water you need. Pick a use case for a typical ratio, or enter your own.
The ratios shown are guidelines. Always read your product label; manufacturers vary widely.
Too strong a mix wastes product and can streak or damage; too weak and it simply will not work. The right ratio gets the most out of your concentrate and is far cheaper than ready-to-use products.
Snow foam is misted thinly over the whole car and diluted heavily (often 1:10 to 1:20 in the lance bottle). An APC is diluted lightly for interiors and stronger for heavy soiling such as engines and wheels. Car shampoo goes in very diluted, into the bucket.
Ratios differ per brand and per concentrate. Use this calculator as a guideline and follow the label for the exact advice.