Two roasts can finish at the same color and the same weight loss and still taste completely different. One of the biggest reasons is development time ratio — how much of the roast happened after first crack. DTR is one number that captures the shape of a roast, and learning to read it is how home roasters move from "it tasted fine" to "I know why it tasted that way."
Open the roast log →Development time is the stretch from the start of first crack to the drop — the part of the roast where flavor really forms. DTR expresses that stretch as a percentage of the total roast time:
An example: if first crack starts at 9:00 and you drop at 11:00, your development time is 2:00 out of an 11:00 total roast — about 18% DTR. The same 2-minute development on a longer 12:00 roast would be about 17%; on a fast 9:30 roast it would be closer to 21%. That's the point of the ratio — it normalizes development against the whole roast, so it's comparable across batches of different lengths.
Most balanced roasts land in the 15–25% range, with many roasters aiming around 20%. As a rough map:
These are starting reference points, not rules. The ideal DTR depends on the bean, the roast level you want, and your roaster's heat profile. Lighter roasts often live at the lower end; the right answer is whatever your tasting notes tell you.
DTR is most powerful as a tuning knob you adjust between batches. If a roast tasted sharp or sour, try extending development a little (drop later, or ease the heat after first crack) to nudge DTR up. If it tasted dull and baked, shorten development to bring it down. Because it's a ratio, you can compare a 200 g batch to a 250 g batch fairly, even when total times differ.
The catch is that it depends entirely on logging an accurate first-crack time — so listen carefully and mark it the moment the pops begin. RoastLog takes your first-crack and drop times in mm:ss and calculates DTR automatically as you type, then keeps it alongside weight loss, roast level and your tasting note so you can connect the number to the cup, batch after batch.
Track your DTR →Related: First crack explained · Roast weight loss · RoastLog app