Coffee-Water Ratio Calculator Formula

Understand the math behind the coffee-water ratio calculator. Each variable explained with a worked example.

Use the Coffee-Water Ratio Calculator

Formulas Used

Coffee Needed

coffee_grams = brew_method == 500 ? cups * 18 * strength : cups * 177 / (1000 / brew_method) * strength

Water Needed

water_ml = brew_method == 500 ? cups * 36 : cups * 177

Coffee (tablespoons)

coffee_tbsp = brew_method == 500 ? cups * 18 * strength / 5 : cups * 177 / (1000 / brew_method) * strength / 5

Ratio

ratio_display = brew_method == 500 ? 2 : 1000 / brew_method / strength

Variables

VariableDescriptionDefault
brew_methodBrew Method60
cupsCups of Coffee(cups (6 oz))4
strengthStrength Preference1

How It Works

How to Calculate Coffee-to-Water Ratio

Standard Ratios

  • Drip / Pour-Over: 1:16 (60 g per liter)
  • French Press: 1:14 (70 g per liter)
  • AeroPress: 1:12 (versatile, can be diluted)
  • Espresso: 1:2 dose-to-yield (18 g in, 36 g out)

    • Formula

    Coffee (g) = Water (mL) x Ratio per Liter / 1000 x Strength Factor

    One standard "cup" of coffee is 6 oz (177 mL). The SCA (Specialty Coffee Association) golden ratio is 55-65 g per liter.

    Grind Size Matters

    The ratio assumes the correct grind for the method. Too fine = over-extraction (bitter). Too coarse = under-extraction (sour, thin).

    Worked Example

    4 cups of drip coffee, standard strength.

    brew_method = 60cups = 4strength = 1
    1. 01Water = 4 x 177 = 708 mL
    2. 02Coffee = 708 x 60 / 1000 = 42.5 g
    3. 03About 8.5 tablespoons of ground coffee
    4. 04Ratio = 1:16.7 water to coffee

    Ready to run the numbers?

    Open Coffee-Water Ratio Calculator