Cold Brew Calculator
Cold brew water, yield, and servings from grounds and ratio.
What it does
Cold brew runs on weight ratios, not scoops. One part coffee to ten parts water gives a balanced batch to drink straight; one to eight gives a concentrate to dilute. The grounds drink first: they keep about twice their weight in water, so yield always lands under brew water.
The tool above runs four ratios in both unit systems. Enter grounds weight and pick 1:5, 1:8, 1:10, or 1:14, and it prints brew water, strained yield, and 4 oz servings. Defaults brew 100 g at 1:10 into 1,000 g water and 800 g yield.
Coffee authorities frame the bands. The National Coffee Association sets 1:4 to 1:5 with coarse grind and ~12 hour steeps, and immersion brewing research models retention near twice the grounds weight. Home ladders extend the anchor: 1:8, 1:10, and 1:12-1:16 for milder pitchers.
Steep discipline finishes the cup. Coarse grounds, room temperature or cooler, 12 to 24 hours, then a full strain before chilling. Concentrate dilutes 1:1 at serving; ready-to-drink ratios pour straight over ice.
How to use
- Pick metric (g) or imperial (oz).
- Enter the coffee grounds weight.
- Pick the ratio: 8 concentrate, 10 balanced, 14 RTD.
- Read brew water first, then strained yield.
- Read 4 oz servings.
- Steep 12-24 h coarse, then strain.
Formula
- grounds
- Coffee grounds: g or oz by system.
- ratio
- Water grams per gram: 5, 8, 10, or 14.
- 2x retention
- Water held by spent grounds.
NCA anchors 1:4 to 1:5 with ~12 h steeps; retention ~2x grounds follows immersion brewing research (Liang/Ristenpart).
Worked example
Example: 100 g at 1:10
Metric defaults: 100 g at 1:10. Imperial mirrors at 3.5 oz.
- Inputs: 100 g grounds at 1:10 balanced.
- Water: 100 x 10 = 1,000 g.
- Retained: 2 x 100 = 200 g stays in grounds.
- Yield: 1,000 minus 200 = 800 g.
- Servings: 800 / 120 = 6.7. Tool shows 1000 g water, 800 g yield, 6.7 servings.
Reference table
| Style | Ratio | Grounds/L |
|---|---|---|
| Extra strong | 1:5 | 200 g |
| Concentrate | 1:8 | 125 g |
| Balanced | 1:10 | 100 g |
| Ready to drink | 1:14 | 71.4 g |
| Mild | 1:16 | 62.5 g |
Limits
- Planning math only. Grind and bean shift extraction.
- Retention 2x is typical, not lab exact.
- Dilution taste stays personal.
- Caffeine math sits on the tea/coffee pages.
Common mistakes
- Measuring scoops instead of weighing.
- Fine grinds that over-extract bitter.
- Short steeps under 12 hours.
- Skipping the retention loss in yield.
- Serving concentrate straight unknowingly.
Try it yourself
Quick checks. Answers sit tucked under each question.
80 g at 1:8 concentrate?
Water 80 x 8 = 640 g. Retained 160 g. Yield 480 g, 4 servings.
60 g at 1:14 ready to drink?
Water 60 x 14 = 840 g. Retained 120 g. Yield 720 g, 6 servings.
Questions
What do the ratios mean?
Water grams per gram of coffee: 1:8 concentrate, 1:10 balanced, 1:14 ready to drink, 1:5 extra strong.
How is yield figured?
Water minus twice the grounds weight. At 1:10 with 100 g: 1,000 minus 200 = 800 g.
How long does it steep?
About 12 hours typical per NCA, range 12 to 24. Coarse grind at room temp or cooler.
How do I serve concentrate?
Dilute 1:1 with water or milk. The 1:8 batch doubles at serving time.
Does imperial work the same?
Same ratio by weight: 3.5 oz at 1:10 needs 35 oz water for 28 oz yield.
Does grind size matter?
Yes. Finer grinds over-extract bitter notes and clog filters; keep it coarse.
Sources
- National Coffee Association: Cold Brew Coffee (1:4-1:5, 12 h)
- Liang et al. 2021: Immersion Brewing Model (retention, Scientific Reports)
- SCA: Coffee Standards (standards body)