Brew profile
min
ml
°C
g
ml
Your brew over time
Strength (TDS)
Temperature
Extraction
Configure your brew and press Simulate
Ready to drink
--
when cool enough to sip
Ideal strength window
--
when strength is in the sweet spot
Flavour extraction
--
of flavour pulled from the grounds
Brew simulator
See how grind size, water temperature, and brew time affect your coffee's strength and flavour. Pick a preset or adjust the sliders, then press Simulate.
Brewing tips for Brewline
Too strong?
Use a coarser grind or try the 2-stage brew: add 50 ml of cold water after 2 to 3 minutes to slow extraction and extend your drinking window.
Too weak or sour?
Go finer on the grind or increase your coffee dose. With Brewline, extraction continues as you sip, so the last third of your cup will always be the strongest.
High altitude?
Above 2,000 m, water boils below 94 °C. Use a finer grind to compensate for the slower extraction rate, and consider a double-wall vessel to retain heat longer.
Understanding your brew
New to immersion brewing? Here is what the numbers mean and how to get the cup you want.
TDS stands for Total Dissolved Solids. It measures the percentage of coffee solubles dissolved in your water. In plain terms, it tells you how strong your cup tastes. A TDS of around 1.15 to 1.35% is considered the sweet spot by most coffee professionals: flavourful without being overpowering. Below that range, coffee can taste watery; above it, it may feel harsh or muddy.
Extraction is the percentage of flavour compounds pulled from the coffee grounds. Coffee beans contain roughly 30% soluble material, but not all of it tastes good. The ideal range is 18 to 22%. Below 18% (under-extracted), you get sour, thin, or grassy flavours because only the fast-dissolving acids have come out. Above 22% (over-extracted), bitter and astringent compounds start to dominate. The simulator shows you when your brew crosses these thresholds so you can time your sipping accordingly.
This is the most common challenge with immersion brewing: extraction keeps going while you wait for the coffee to cool. You have several options. Use a coarser grind to slow the extraction rate. Add cold water mid-brew (toggle the option in the simulator) to drop the temperature quickly and slow extraction at the same time. Or use less coffee so the overall strength stays in the sweet spot longer. Try simulating each approach to compare.
Sour or thin coffee is typically under-extracted: the water has not pulled enough flavour from the grounds. Try a finer grind, which exposes more surface area and speeds up extraction. You can also increase your coffee dose (more grounds per cup) or use hotter water. In the simulator, watch for the extraction line: if it stays below 18%, your brew is under-extracted.
Grind size controls how fast flavour dissolves out of the coffee. Finer grinds have more surface area, so they extract faster and produce a stronger cup in less time, but they also risk over-extraction if you brew too long. Coarser grinds extract more slowly, giving you a wider window to drink at the right strength. For Brewline, Coarse is a good starting point because it balances extraction speed with a comfortable drinking window.
Different materials absorb and release heat at different rates. Thin-walled cups (steel, titanium, glass) lose heat quickly, so the coffee cools faster and extraction slows down sooner. Double-wall vessels insulate well and keep the brew hotter for longer, which means extraction continues at a higher rate. A ceramic mug sits in the middle. If your coffee is getting over-extracted, switching to a thinner cup can help; if it is cooling too quickly and tasting weak, a double-wall vessel retains heat better.
The ideal strength window shows the time range during which your coffee's TDS falls within the generally accepted sweet spot (1.15 to 1.55%). This is the period when your cup will taste the most balanced. If the window is short or does not appear, try adjusting grind size or dose. A wider window means more time to enjoy your coffee at its best.
This means the coffee stays above 65 °C (149 °F) for the entire simulated brew time. In other words, it never cools enough to sip comfortably within your chosen duration. You can increase the brew time to see when it does cool, add cold water to bring the temperature down sooner, or switch to a thinner vessel that sheds heat faster. With Brewline, drinking through the straw also makes hot coffee more sippable because only a small stream touches your lips at a time.