The Agtron number is a standardized measurement of coffee roast degree using near-infrared (NIR) spectrophotometry. Developed by Agtron Inc., it assigns a numerical value typically ranging from 25 (very dark) to 110 (very light) on the Gourmet scale. Professional roasters use Agtron meters to ensure roast consistency across batches. Higher numbers indicate lighter roasts, while lower numbers indicate darker roasts. The Specialty Coffee Association (SCA) recognizes Agtron as the industry standard for roast color classification.

This tool provides an approximate estimation based on visual color matching using grayscale luminance mapping. It is not a replacement for a professional Agtron spectrophotometer, which uses precise NIR reflectance technology. Our estimator can typically get within ±5–10 Agtron points of actual readings, making it useful for home roasters, cupping sessions, and quick visual references. For commercial or competition-grade accuracy, we recommend using a calibrated Agtron device.

The Gourmet scale (0–133) is used for specialty and whole-bean coffee, providing finer granularity for lighter roasts. The Commercial scale (0–100) is designed for ground coffee and darker roasts commonly found in commercial settings. This tool uses the Gourmet scale, which is the standard for specialty coffee. A Gourmet value of ~75 roughly corresponds to a Commercial value of ~55. Most specialty roasters reference the Gourmet scale when discussing Agtron numbers.

For the most accurate Agtron reading, ground coffee is preferred because it presents a uniform surface for NIR measurement. Whole beans can give slightly different readings due to surface variations, chaff, and roasting unevenness. Professional Agtron meters typically require a sample of ground coffee pressed into a petri dish. When using our visual estimator, grinding the coffee first and matching the ground color will yield a more reliable estimate.

Espresso is traditionally roasted slightly darker than filter coffee. The ideal Agtron range for espresso is typically 55–75 on the Gourmet scale (Medium to Medium Dark). This range develops rich chocolate and caramel notes while maintaining enough sweetness and reducing excessive acidity. Lighter espresso roasts (Agtron 70–80) have gained popularity in modern specialty coffee for highlighting fruit-forward single-origin characteristics, though they require more precise extraction.

First Crack typically occurs around Agtron 85–95 (Light/City roast range), signaled by audible popping sounds as beans expand and release moisture. Second Crack begins around Agtron 45–55 (Dark/French roast range), with a quieter, crackling sound as the bean structure breaks down further. Many roasters use these auditory cues alongside Agtron measurements. Roasts dropped just after First Crack (Agtron 75–85) are City+ / Medium Light, while roasts approaching Second Crack (Agtron 55–65) are Vienna / Medium Dark.

Yes! Our tool includes an image color picker feature. Upload a photo of your coffee beans (or ground coffee), then click on the bean surface to sample its color. The tool will estimate the corresponding Agtron number. For best results, use photos taken in natural daylight without strong shadows or color casts. Note that camera sensors and screen calibrations vary, so this method provides an approximation rather than a lab-grade measurement.

Variations between Agtron devices can arise from: calibration differences (each unit needs periodic calibration with reference tiles), sample preparation (grind size, packing density, surface smoothness), bean origin (different coffee varieties may reflect NIR differently at the same roast level), and measurement conditions (ambient light, temperature). The SCA recommends using Agtron as a relative reference within a single roasting operation rather than an absolute universal standard.