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Prothrombin Time (Quick %) Unit Converter
Prothrombin Time (PT) is a measure of the extrinsic pathway of coagulation. In addition to the standard reporting in Seconds and INR, the **Quick Value (Quick %)** is a method often used in European countries to express PT activity.
The Quick value represents the activity of coagulation factors as a percentage of normal. A value of 100% corresponds to a normal clotting time, while lower percentages indicate prolonged clotting times (reduced activity). This converter facilitates switching between Seconds, INR, and Quick %.
Activity & Ratio
StandardQuick % is roughly inversely proportional to INR.
Clotting Time
Clinical Context
Reference Ranges:
• Quick %: 70% – 130% (Normal).
• Therapeutic Range (Warfarin): Typically 20% – 40% activity (corresponds to INR 2.0-3.0).
Conversion Logic (Approximation):
This calculator uses a standard approximation where MNPT (Mean Normal PT) is 12.0 seconds and ISI is 1.0.
Quick % ≈ (MNPT / Patient PT) × 100.
INR = (Patient PT / MNPT)ISI.
Clinical References
How to Use This Converter
Follow these steps to convert between Quick %, INR, and Seconds.
Enter Values
Input your result into the corresponding field (e.g., Quick %).
Automatic Conversion
The calculator instantly approximates the corresponding INR and Seconds.
Reset
Use the Clear button to reset all fields.
Frequently Asked Questions
Quick % measures activity relative to normal plasma (higher is better). INR is a ratio standardized for Warfarin monitoring (lower is “normal”).
No. “Quick” curves are specific to the lab’s reagent. This tool uses a standard hyperbolic approximation for estimation.