Reducing caffeine · Evidence-led guide
Half-caf vs decaf: compare caffeine without assuming zero
The short answer
A 50:50 blend averages two comparable caffeine values. If the lower-caffeine component is not zero, the result is not exactly half the regular component.
| Regular proportion | Regular component | Lower-caf component | Estimated total |
|---|---|---|---|
| 0% | 0 mg | 4 mg | 4 mg |
| 25% | 25 mg | 3 mg | 28 mg |
| 50% | 50 mg | 2 mg | 52 mg |
| 75% | 75 mg | 1 mg | 76 mg |
| 100% | 100 mg | 0 mg | 100 mg |
Inputs are hypothetical 100 mg and 4 mg per equal final serving. Formula: regular fraction × 100 + remaining fraction × 4. These are not measured coffee values.
Use comparable inputs
Both numbers must describe comparable finished servings. Mixing a whole mug value with a per-shot value makes the arithmetic misleading. If the inputs refer to dry beans rather than brewed coffee, extraction adds uncertainty that a simple blend formula cannot remove.
Keep the nonzero remainder
With the hypothetical values above, a 50:50 blend is 52 mg rather than 50 mg. Keeping the smaller component visible makes the assumptions auditable. It does not imply the example matches a café’s branded half-caf recipe.
A planning aid, not a guarantee
Use the calculator to explore ratios and keep preparation consistent when comparing your own batches. A calculated blend is neither a personal medical recommendation nor a laboratory measurement of the drink.
Sources and scope
- CaffCalc blend calculator and arithmeticOriginal weighted-average example using hypothetical equal-serving inputs; not a manufacturer recipe or clinical study.
Educational information, not medical advice. Published, calculated and approximate values have different limits. Check the current product label or recipe when an exact amount matters.