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What the Numbers on Coffee Bags Actually Mean
Coffee bags are covered in numbers — altitude in metres, grading scores out of 100, roast level scales from 1 to 5, screen sizes, moisture content percentages, bag weights in grams. Most of these numbers are either meaningless marketing or specialist information that affects roasters and buyers, not home baristas. This guide explains which numbers actually matter and what to do with them.
🔗 Part of our complete coffee expert guide. Our UK espresso beans guide applies this knowledge to specific buying recommendations.
The Numbers That Actually Matter
The Roast Date
The single most important number on any coffee bag. Not the “best before” date — the actual roast date, which tells you when the coffee was roasted. Coffee is best consumed between 7 and 28 days after roasting for espresso, or 5-14 days for filter. A bag with a roast date from last week is almost always better than an expensive bag with no roast date. If there is no roast date — only a best before — treat it as stale by default.
Altitude (metres above sea level)
Higher altitude means slower bean development, denser beans, more complex sugars and — generally — more interesting and acidic flavour. Below 1,000m tends to produce lower-acid, heavier-bodied coffee. Above 1,500m tends to produce brighter, more complex cups. Above 2,000m is exceptional and rare. This number is a genuine quality indicator: altitude above 1,400m on an Ethiopian or Kenyan is a positive signal worth noticing.
The SCA Score (out of 100)
The Specialty Coffee Association grades green (unroasted) coffee on a 100-point scale. Coffee scoring above 80 is considered “specialty grade.” Above 85 is excellent. Above 90 is exceptional and rare. If a bag claims an SCA score, it is a meaningful quality indicator — but it measures the green bean before roasting, not the finished product. A high SCA score is a good sign, not a guarantee. Scores below 80 should not appear on specialty bags at all.
Roast Level (1-5 or light/medium/dark)
Some roasters use a numerical scale — 1 being very light, 5 being very dark — others use descriptive terms. This number directly affects what you taste. Lower numbers mean more of the bean’s natural origin character: more acidity, more fruit, more complexity. Higher numbers mean more of the roasting process: more bitterness, more chocolate, more body, less origin character. For espresso with milk, 2-3 tends to work well. For black espresso, 1-2 lets you taste the origin. For those who like traditional strong espresso, 3-4.
Bag Weight (grams)
Standard bags are 250g or 1kg. A standard double espresso uses 18g of coffee. A 250g bag gives you approximately 13-14 double espressos. For daily use this means a 250g bag lasts roughly two weeks for a single daily coffee drinker, one week for two. This is relevant to freshness planning — buy bag sizes you will use within 2-3 weeks of opening.
The Numbers That Are Mostly Marketing
Screen Size
Coffee beans are graded by size using a screen (a mesh with specific hole sizes). Screen 18 means the bean passed through an 18/64-inch screen. Larger beans are often associated with higher quality, but size alone is not a reliable quality indicator. This number appears on some specialty bags and is essentially professional-grade information that does not affect home brewing decisions.
Moisture Content Percentage
Green (unroasted) coffee should have a moisture content of around 10-12% for optimal roasting. This number is aimed at roasters assessing raw green coffee, not consumers buying roasted bags. If it appears on a consumer bag it is either transparency signalling or filler information.
Harvest Year
The year the coffee cherries were harvested — not the same as the roast date. A 2024 harvest roasted in early 2026 would be considered past its prime as a green bean — the freshness window for green coffee is typically 6-18 months post-harvest. Seeing “2026 harvest” on a bag in 2026 is meaningful and positive. Seeing “2024 harvest” in 2026 warrants caution unless it is a naturally aged coffee intentionally so.
How to Read a Bag in 30 Seconds
- Find the roast date — if there is none, consider a different bag
- Check the roast date is within the last 3-4 weeks
- Note the origin — Ethiopia, Colombia, Brazil, Kenya are all reliable starting points
- Note the roast level — light for complexity, medium for balance, dark for intensity
- Check the SCA score if present — above 85 is genuinely good
- Check the altitude if you care about acidity and complexity — above 1,400m is a good sign
The Number That Overrides All Others
Roast date. A coffee with a roast date from two weeks ago and an SCA score of 83 will almost always taste better than a coffee with an SCA score of 88 and no roast date. Freshness is not a premium attribute — it is the baseline below which nothing else matters. Every other number on the bag is secondary to this one.