Coffee Calculators
Water Bypass Calculator
https://www.coffeesizing.com/calculators/water-bypass/
Estimate only — not a cupping score, a water lab or a roast profile. Confirm on a test brew.
Water Bypass Calculator
Bypass is clean water into already-extracted coffee. You lower TDS (strength) without pulling more from the bed — unlike a longer V60 that keeps extracting. Batch brewers do this on purpose; Americano is the espresso version. Weigh the brewed mass, read TDS, pick a target.
Inputs
Results
- Bypass water
- 57.7g
- Final beverage
- 307.7g
Recommended gear
0.1 g coffee scale
Bypass is a mass of water. Pour it on the scale in the server, do not ‘add a splash’.
Typical range: $20–$80
Coffee refractometer
Without brewed TDS this is a guess. Measure, dilute, measure again if you are learning the batch brewer.
Typical range: $80–$400
Chemex
A big server is where bypass is honest. Brew concentrated, then water to the line you actually drink.
Typical range: $40–$60
Calculation method
Dissolved solids mass is conserved. Bypass water equals brewed mass times (brewed TDS / target TDS − 1). 250 g at 1.6% toward 1.3% needs about 58 g of water and finishes near 308 g. Extraction yield of the grounds does not change; you only changed strength.
Café batch brew
Many urns brew a touch strong on purpose so bypass can hit a TDS spec after hold time. Home Chemex can do the same when guests want a milder cup without a second pour-over.
Frequently asked questions
Hot or cold bypass?
Hot keeps serving temperature; cold makes an iced batch. Mass is mass. Temperature is a separate thermal problem.
Is this the same as a weaker brew ratio?
No. A weaker ratio extracts differently. Bypass extracts first, then dilutes. Use it when the bed already hit the EY you want.
Target higher than brewed TDS?
You cannot concentrate with water. Brew less water next time, or evaporate, which this page will not do.
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