Spirit Run Jar Planner

Before your spirit run, enter your low wines volume and ABV, choose a jar size (500 mL is standard for a home pot still), and select your spirit style. The planner models the ABV curve across your entire run and assigns each jar to a single fraction — foreshots, heads, hearts, or tails. When a cut point falls mid-jar, the current jar is sealed and a new one starts, even if it is only partially filled. This reflects real distilling practice: you never continue filling a jar past a cut point.

What low wines ABV to enter. If you ran a stripping run, your low wines will typically be between 20–40% ABV depending on how far you ran it. Higher ABV low wines produce more distillate per litre of charge. For a single-distillation wash run, enter your fermented wash ABV directly.

Choosing a jar size. 500 mL is the most practical size for a medium pot still run — small enough to give you control, large enough that you are not constantly switching jars. For smaller runs or more precise work around cut points, 200–250 mL jars give finer control. For large runs, 1 L or 2 L containers are common.

Take it to the still. Print the schedule or keep it open on your phone. Use the jar numbers and expected ABVs as a guide for when to start paying close attention. Begin sensory evaluation a jar or two before each predicted cut point.

Always verify with instruments. A parrot alcoholmeter gives real-time ABV readings as distillate flows. Use the schedule as a roadmap, not a guarantee — your actual run will follow the same shape of curve but exact jar numbers depend on your still's efficiency and heating rate.

Foreshots (Jar 1). The first fraction off the still — always discard, never taste. The planner calculates 3 mL per litre of low wines charge (minimum 20 mL), consistent with the standard guidance of approximately 50–60 mL per 20 L. The foreshots jar will always be a partial jar.

Heads. Come over after foreshots while ABV is still high. Contain elevated acetaldehyde and ethyl acetate — sharp, solvent-like, sometimes fruity. Discard or collect as feints to add to your next run. The last heads jar is partial — it runs until the ABV hits your hearts-start cut point.

Hearts. The clean, drinkable middle fraction. The schedule shows total hearts yield in litres. Hearts jars run at full jar volume except the last one, which is partial. The ABV spans from your hearts-start cut down to your hearts-end cut.

Tails. As ABV drops, fusel oils and higher alcohols concentrate. Character becomes hot and oily. Most distillers collect tails as feints to add back to the next run in small proportions. Collection stops at your chosen stop ABV, typically 20–25%.

Partial jars. The foreshots jar, the last heads jar, the last hearts jar, and the final tails jar will all be partially filled. The planner seals each jar the moment the fraction changes. Never top up a partial cut jar with the next fraction.

During a pot still spirit run, the ABV of the distillate follows a predictable decline from start to finish. The run starts high — typically 80–85% ABV for a pot still — and drops continuously as the ethanol in the boiler is depleted. The jar planner models this as an exponential decay curve, which closely matches the behaviour of a real pot still running at steady heat.

Why exponential decay? The rate at which ethanol concentration falls is proportional to the current concentration — the richer the boiler, the faster it depletes. This is why heads represent a relatively small volume (ABV drops fast) while tails represent a large volume (ABV drops slowly near the end of the run).

Column stills behave differently. A column still achieves higher rectification — the ABV peaks higher (typically 88–92%) and the hearts zone is tighter and more neutral. The planner applies a higher peak ABV and efficiency for column stills, producing fewer heads jars and a narrower hearts window.

Still efficiency. The planner uses 88% efficiency for pot stills and 95% for column stills — the proportion of available ethanol that ends up as distillate. If your actual yield is consistently higher or lower, your still runs at a different efficiency. Adjust your expectations based on what you observe over multiple runs.

The spirit type presets set sensible default cut ABVs, but these are starting points — your palate makes the final call. Here is what each preset assumes and why:

Whisky (75% / 62% / 25%). Wider cuts preserve congeners — the flavour compounds that give whisky its character. Cutting earlier for hearts and wider for tails gives a fuller, more complex spirit. Single malt styles often cut even wider.

Gin (80% / 65% / 25%). Gin needs clean neutral spirit so the botanicals shine. Starting hearts collection later removes harsh heads off-notes that would compete with delicate floral and citrus characters.

Vodka (84% / 78% / 40%). The tightest cuts of any spirit — maximum purity. Very narrow hearts window. Most commercial vodka undergoes multiple distillations to achieve this.

Brandy (70% / 55% / 20%). Deliberately wide cuts include congeners from heads and tails that define the fruity, floral brandy character. Running the still longer and cutting lower is standard practice.

Rum (75% / 60% / 25%). Depends heavily on style. Light rum needs tight cuts for a clean profile; heavy or funky rum deliberately includes more esters from wider cuts.