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Half-Caf Blend Calculator
You do not have to choose between full caffeine and decaf. Blend the two beans and you can land anywhere in between — but a 50/50 split by weight is not quite 50% caffeine, because decaf still carries a little. Enter your dose and the caffeine you actually want, and this calculator gives the exact grams of each bean for every shot.
1Your dose and your target
Presets set the target slider — drag it to land anywhere between decaf-only and full strength.
The total ground coffee in your basket. The blend always adds up to this — only the split changes.
The floor is about 8%, not zero: decaf beans keep roughly 5 mg of caffeine per shot versus about 63 mg in a regular one, and this calculator counts that honestly.
Used for the daily total below — handy when the second or third drink of the day is the one to cut down.
2Weigh these two piles
Caffeine vs a full-caf shot: about 50% · A full-caf shot at this dose is estimated at 126 mg
?Three rules for a blend that tastes right
⚖️ Weigh the split, do not scoop it
Two beans differ in size and density, so a half scoop of each is rarely half and half. Weigh each pile to the gram — the numbers above only work if the split is real.
🫘 Match the beans, not just the ratio
Blend a regular and a decaf with similar roast level and origin style. A light, bright regular against a dark, flat decaf tastes like two coffees arguing, at any ratio.
🔀 Blend per shot, or pre-blend a small jar
Grinding the two together mixes best. Single-dosing? Weigh both piles into the grinder each time. Hopper? Pre-blend only a few days at a time and shake the jar — the beans settle apart.
?Half-Caf FAQ
Why is a 50/50 split not exactly 50% caffeine?
Because decaf is not zero. Decaf beans keep roughly 5 mg of caffeine per shot where a regular shot carries about 63 mg — about 8%. A true 50% target therefore needs slightly less than half regular beans, which is why the calculator gives 8.2 g regular and 9.8 g decaf for an 18 g half-caf dose instead of 9 g and 9 g.
Does half-caf taste like decaf?
No — that is the point. Half the dose is still real, full-flavour coffee, and most people cannot pick a well-matched half-caf blend out from a full-caf shot in a milk drink. Straight espresso shows the difference a little more, mostly in body.
Do regular and decaf beans need the same grind setting?
Close, but check. Decaf beans are often a touch more brittle after processing and can run slightly fast at the same setting. Pull the blend, watch the time, and adjust the grinder for the blend as its own coffee — do not average the two settings.
Can I blend for just the afternoon drink?
Yes, and it is the most common use. Keep your morning shot full-caf, then weigh the afternoon dose at 25–50%. The daily total in this calculator shows what that swap actually saves.
Are these caffeine numbers exact?
No — they are honest estimates. This calculator uses about 63 mg per regular shot (126 mg for a typical 18 g double) and about 8% of that for decaf, matching First Pull's caffeine calculator. Bean, roast, and extraction move the real number; the blend ratio is the part you can control exactly.