Coffee widgets: brew ratios, caffeine estimates and sources

These 9 widgets live in the Coffee category of the library (Coffee) and are all free. Sample content is labeled Sample; the label disappears once you connect My Data or enter your own.

Every caffeine number in these widgets is an estimate. People vary a lot, and this is not medical advice. If you’re pregnant, breastfeeding, on medication or sensitive to caffeine, follow your doctor’s advice.

At a glance

Widget	Data	What it shows
Brew Recipe Timer	Widget settings	Ratio, water, temperature, grind and a pour timeline for V60, Kalita, Chemex, AeroPress, French press, moka pot and cold brew — tap to start the timer
Espresso Shot Timer	This browser only	Tap to start and stop; see if you hit 25–30 s, with a hint to grind finer or coarser. Large size keeps your last 4 shots
Caffeine Tracker	My Data · Coffee log	Tap to log a cup; today’s caffeine, roughly how much is still in your body, and when it drops below your bedtime threshold
Coffee This Month	My Data · Coffee log	Cups, spending, most-ordered drink, daily average and a heatmap of cups per day (amounts can be hidden)
Coffee Stamp Card	My Data · Coffee log	One stamp per cup; collect 10 (or 8 / 12) for a reward you choose
Bean Freshness	Widget settings	Days since roast and whether each bag is resting, at its peak, still good or fading — up to 4 bags
Coffee Tasting Notes	My Data · Tasting notes	Your latest coffees (origin, roast, rating, notes) and how your flavor notes spread across the flavor wheel
Coffee Origins Passport	Widget settings	36 major origins light up on the coffee belt as you taste them, counted by region
Daily Coffee Tip	Written by us	A brewing, bean, history, culture or caffeine tip each day — 40 in all

The two My Data tables

• Coffee log: one entry per cup, with Drink (drip, Americano, iced Americano, latte, cappuccino, flat white, espresso, cold brew, instant, canned, decaf, tea, other), Caffeine (mg), Cost and Note. The Caffeine Tracker, Coffee This Month and the Stamp Card all read this table, so connect them to the same one. Cups and spending are totaled by month and drink; caffeine is also summed into half-hour slots by time (used only for today’s and yesterday’s curve).
• Coffee tasting notes: one entry per coffee, with Coffee, Origin, Roast, Flavor notes (comma-separated) and Rating (1–5). Logging the same coffee again updates it. Add entries from the table in My Data.
• Check-in link: turn on the check-in link for your Coffee log to log a cup from your phone’s home screen in one tap. To log a specific drink, add &v.drink=latte&v.mg=126 after the # (use these values for the drink: drip, americano, iced_americano, latte, cappuccino, flat_white, espresso, cold_brew, instant, canned, decaf, tea, other).

How brew ratios work

• Water = coffee × ratio. 1:15 means 15 g of water for every gram of coffee: 15 g of coffee → 225 g of water. Change the dose or ratio and every “pour to x g” step in the timeline scales with it.
• The SCA Golden Cup standard is about 55 g of coffee per liter of water (±10%), roughly 1:18. Pour-over recipes commonly use 1:15–1:17 for a stronger cup. Brewing water is usually 92–96 °C (198–205 °F).
• The 7 recipes are common starting points, not standards — for example V60 at 15 g / 225 g / 93 °C / medium-fine: bloom with about 3× the coffee’s weight for 45 s, then pour to 60% and 100%. Cold brew is a 1:8 concentrate, 12–18 hours in the fridge, diluted 1:1 with water or milk.
• Espresso: by default 18 g in, a 1:2 ratio (→ 36 g out) and a 25–30 s target, all adjustable. The Italian Espresso National Institute (INEI) defines its certified espresso at 25 ± 5 seconds — but taste decides: sour and thin usually means under-extracted (grind finer); bitter and drying usually means over-extracted (grind coarser).

How caffeine is estimated

Each cup counts the milligrams you logged (quick buttons use the reference values below, and you can set your own). What’s left in your body is estimated in two steps:

1. Absorption: taken up gradually over about 45 minutes (simplified as linear).
2. Elimination: then exponential decay by half-life: remaining = mg × 0.5^(hours ÷ half-life). The default half-life is 5 hours (a commonly cited figure); you can set 2–12 hours.

“Under X mg by …” assumes you don’t drink more, and finds the first time the estimate drops below the threshold, checking every 5 minutes. The default bedtime threshold is 50 mg: in its 2015 opinion, EFSA noted that 100 mg (about 1.4 mg/kg body weight) taken close to bedtime may lengthen the time it takes to fall asleep and shorten sleep in some adults.

Half-life varies widely between people: it’s much longer in pregnancy and with oral contraceptives and some medications, and shorter in smokers. Treat the curve as a rough guide.

Reference values

Drink	Value	Notes
Drip / pour-over coffee, 240 ml (8 fl oz)	95 mg	USDA FoodData Central: brewed coffee ≈ 40 mg / 100 g
Espresso, single shot (~30 ml)	63 mg	USDA: espresso ≈ 212 mg / 100 g
Americano, iced Americano, latte, cappuccino, flat white	126 mg	Estimated as a double shot (common for a medium)
Cold brew	150 mg	Varies a lot with ratio and dilution; a typical middle value
Instant coffee, 240 ml	62 mg	USDA
Canned coffee	80 mg	Varies a lot; a typical middle value
Decaf, 240 ml	2 mg	USDA; EU rules cap decaffeinated roasted coffee at 0.1% caffeine by dry weight
Black tea / green tea, 240 ml	47 mg / 28 mg	USDA

The daily guide defaults to 400 mg: EFSA (2015) considers up to 400 mg a day, and single doses up to 200 mg, generally not a safety concern for healthy adults, and up to 200 mg a day during pregnancy and breastfeeding. The US FDA also cites 400 mg a day as an amount not generally associated with dangerous effects in healthy adults.

Freshness windows and the flavor wheel

• Freshness: for filter, roughly days 4–21 after roasting are the peak and days 22–35 still good; for espresso, roughly days 7–28 and 29–42. These are rules of thumb — the coffee, roast level, packaging and storage all shift them a lot.
• Flavor wheel: the nine categories follow the inner ring of the SCA and World Coffee Research Coffee Taster’s Flavor Wheel (2016): fruity, floral, sweet, nutty / cocoa, spices, roasted, green / vegetal, sour / fermented and other. The widget sorts your notes with a keyword list we wrote in five languages; anything it doesn’t recognize counts as “other”.

Sources for the daily tips

The Daily Coffee Tip entries are written by WidgetStore and checked against: the SCA Golden Cup standard; USDA FoodData Central; EFSA’s Scientific Opinion on the safety of caffeine (2015); Drake et al., Journal of Clinical Sleep Medicine (2013), on 400 mg of caffeine taken 0, 3 or 6 hours before bed; EU Directive 1999/4/EC (decaf); UNESCO’s Intangible Cultural Heritage lists (Turkish coffee 2013, Arabic coffee 2015); and the invention years of the brewers (moka pot 1933, Chemex 1941, Hario V60 2004, AeroPress 2005). The Kaldi origin story is explicitly labeled a legend.

Privacy

• Your Coffee log and tasting notes live in your own My Data, where you can export or delete them.
• On a public page, turn on Hide amounts in Coffee This Month, and turn off Allow logging in the widget in the Caffeine Tracker and Stamp Card so visitors can’t log cups for you.
• The brew and espresso timers are stored only in this browser and never uploaded.