🥣 Mason-Jar Cold Brew Scaling Calculator
Pick your jar size & strength — we’ll tell you exactly how much coffee & water to use
Coffee Grounds Needed
106
grams
(~3.7 oz or ~1 cup coarse-ground coffee) — 1:8 ratio in a 32 oz jar
~852 ml
Cold Water
(fill to fill-line)
(fill to fill-line)
~28.8 oz
Cold Water
(fl oz)
(fl oz)
~750 ml
Finished Yield
(after straining)
(after straining)
Coffee grounds — 106 g (~1 cup)
Cold water fill — ~852 ml (~28.8 fl oz)
Headspace — ~95 ml (10%)
Leave headspace so you can shake the jar without spilling. Cap, steep 12–18 h, then strain.
Serving & Dilution Guide
Drink as-is
Pour straight over ice. Best for balanced/ready-to-drink batches.
→ ~3.1 servings (8 oz each)
1 part brew : 1 part water/milk
Classic dilution for concentrates — lightens body, halves caffeine per oz.
→ ~6.2 servings after dilution
Mason Jar Tips
Use wide-mouth jars — easier to spoon grounds in and straining is simpler.
Measure grounds by weight when possible. Volume measurements vary wildly by roast and grind.
Gently swirl once after adding water to ensure all grounds are saturated — don’t shake hard (it can over-agitate).
Steep at room temp for 12–18 hours, or refrigerate for 16–22 hours. Taste-test at the low end.
Strain twice: (1) through a fine-mesh sieve, (2) through a coffee filter or nut-milk bag for clarity.
Actual jar capacity varies slightly by brand. Ball/Kerr wide-mouth jars are the most common. 16/32/64/128 oz are nominal capacities — true fill-to-shoulder volume is about 5–8% less.