tags: [] - coffee/brewing - coffee/brewing/fundamentals aliases: - Brewing Control Chart - Coffee Brewing Chart - SCA Brewing Control Chart

Brewing Control¶

Tags: #coffee/brewing #coffee/brewing/fundamentals Aliases: Brewing Control Chart, Coffee Brewing Control, SCA Brewing Control Chart Related: Extraction | TDS (Total Dissolved Solids) | Extraction Yield | Brew Ratio | Brewing Fundamentals MOC Status: ✅ Complete

Overview¶

The Brewing Control Chart is a visual diagnostic tool that maps the relationship between extraction yield (the percentage of coffee solids dissolved during brewing) and beverage strength (Total Dissolved Solids, or TDS). Developed in the 1950s by Dr E.E. Lockhart, the chart enables brewers to identify where a specific brew falls on a two-dimensional flavour map and understand which variables to adjust to reach the optimal zone. It remains the reference framework used by the Specialty Coffee Association (SCA) for filter coffee standards.

brewing_control_chart

Chart Axes¶

Horizontal axis (x) — Extraction Yield: The percentage of the dry coffee mass that dissolves into the water during brewing. Measured as a percentage; the SCA optimal range is 18–22%.

Vertical axis (y) — Strength (TDS): The concentration of dissolved coffee material in the final cup, expressed as a percentage of the total beverage mass. The SCA optimal range is 1.15–1.35%.

Together, the axes plot where a brew falls on a spectrum from watery to intense and from sour to bitter.

The SCA Optimal Zone¶

The SCA defines a "Golden Cup" zone at the centre of the chart, requiring:

Extraction Yield: 18–22%
TDS (Strength): 1.15–1.35%

Brews landing within this zone are generally perceived as balanced, with optimal sweetness and pleasant acidity. The zone does not represent a single target point but a range within which most palates find the brew acceptable.

Brew Ratio Diagonals¶

Diagonal lines running across the chart represent specific brew ratios (grams of coffee per litre of water, or 1:X ratios). A brewer can move along a specific diagonal by adjusting extraction variables — grind size, water temperature, brew time — without changing the dose. Moving to a different diagonal requires changing the brew ratio itself.

Diagnostic Flavour Zones¶

Zone	Extraction	TDS	Flavour profile
Centre (optimal)	18–22%	1.15–1.35%	Balanced, sweet, complex
Top-left	<18%	>1.35%	Strong, sour, salty, under-developed
Top-right	>22%	>1.35%	Strong, dry, bitter, astringent
Bottom-left	<18%	<1.15%	Weak, watery, sour
Bottom-right	>22%	<1.15%	Weak, watery, harsh

Practical Use¶

A brewer uses the chart by measuring the TDS of a finished brew with a refractometer, calculating extraction yield from the brew ratio and TDS, then plotting the result. If the brew falls outside the optimal zone, the chart indicates which variable to adjust:

Too far left (under-extracted): grind finer, increase temperature, or increase brew time
Too far right (over-extracted): grind coarser, reduce temperature, or reduce brew time
Too high on the y-axis (too strong): increase brew ratio (more water per gram of coffee)
Too low on the y-axis (too weak): decrease brew ratio (less water per gram of coffee)

Key Facts¶

Developed by Dr E.E. Lockhart in the 1950s; adopted and refined by the SCA
SCA optimal extraction yield: 18–22%; optimal TDS strength: 1.15–1.35%
Diagonal lines represent brew ratios; movement along a diagonal requires changing extraction variables, not the dose
A refractometer is needed to measure TDS; extraction yield is calculated from TDS and brew ratio
The chart applies to filter/drip coffee; espresso uses different extraction and strength targets

References¶

Changelog¶

Date	Change
2026-04-30	Compliance review: full rewrite — double frontmatter block, non-standard tags, broken image path (`../`), hidden HTML elements, raw URL footnotes, email address in footer, missing metadata block and required sections; Australian English applied

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