Compressibility Index Calculator
Calculate powder flow properties using Carr's Index and Hausner Ratio
USP/Ph. Eur. Standards
Powder Properties
*Tapped volume after standard tapping procedure (e.g., 500–1250 taps).
Carr's Index Scale
5–15%Excellent – Good
16–20%Fair
21–25%Passable
26–31%Poor
>31%Very Poor
Hausner Ratio Scale
< 1.18Excellent
1.18 – 1.25Good
1.25 – 1.35Fair
1.35 – 1.45Poor
> 1.45Very Poor
USP Procedure
- Weigh 25–100g of powder accurately.
- Pour into graduated cylinder (without compaction).
- Read initial unsettled volume V₀.
- Tap cylinder 500 times (USP I) or until volume change <2 mL.
- Read tapped volume Vₜ.
- Calculate CI and HR.
Applications
- • Tablet compression formulation
- • Capsule filling optimization
- • Powder blending assessment
- • Excipient selection
- • Process validation (QbD)
Flowability Classification Reference
| Carr's Index (%) | Hausner Ratio | Flow Character | Typical Example |
|---|---|---|---|
| <10 | 1.00–1.11 | Excellent | Glidants, free-flowing granules |
| 11–15 | 1.12–1.18 | Good | Lactose, MCC |
| 16–20 | 1.19–1.25 | Fair | Starch, some APIs |
| 21–25 | 1.26–1.34 | Passable | Fine powders, cohesive blends |
| 26–31 | 1.35–1.45 | Poor | Very cohesive, need granulation |
| >31 | >1.45 | Very Poor | Extremely cohesive, must granulate |