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

    Frequently Asked Questions

    Why does coffee taste bitter?

    Bitterness usually comes from over-extraction: too fine a grind, too hot water (over 205°F), or too long a brew time. Try a coarser grind, lower water temperature (195-205°F), or shorter brew time.

    Should I use a scale for coffee?

    Yes. A kitchen scale (accurate to 0.1 g) is the single best upgrade for coffee consistency. Volume measures (scoops, tablespoons) vary significantly because grind sizes and bean densities differ.

    What is the ideal water temperature for coffee?

    The SCA recommends 195-205°F (90.5-96°C). Water that is too hot extracts harsh compounds; water that is too cool under-extracts, producing weak, sour coffee. Just off the boil is usually perfect.

    Ready to run the numbers?

    Open Coffee-Water Ratio Calculator