Centipoise to Pascal-seconds

How Many Pascal-seconds in a Centipoise?

One centipoise (cP) equals exactly 0.001 pascal-seconds (Pa·s), or equivalently, 1 millipascal-second (mPa·s). To convert centipoise to pascal-seconds, divide the cP value by 1,000 (or multiply by 0.001). Centipoise is the most widely used viscosity unit in industry because it produces convenient numbers for common fluids: water at 20°C is about 1.0 cP, motor oil ranges from 50-500 cP, honey is about 2,000-10,000 cP, and ketchup can be 50,000-100,000 cP. The pascal-second is the official SI unit, but its values are inconveniently small for everyday fluids (water is 0.001 Pa·s). Petroleum engineers, food scientists, pharmaceutical researchers, paint formulators, and polymer chemists all measure viscosity in centipoise but may need to convert to Pa·s for engineering calculations, computational fluid dynamics (CFD), or compliance with SI-based specifications. The conversion is especially common when bench viscometer data has to move into SI-based reports, pump calculations, or shear-modeling software. It also keeps supplier specs, internal QC limits, and engineering models describing the same fluid on the same scale. That matters during scale-up and regulatory review.

How to Convert Centipoise to Pascal-second

1. Start with your viscosity value in centipoise (cP).
2. Divide by 1,000 to get pascal-seconds (Pa·s).
3. For example, 500 cP / 1,000 = 0.5 Pa·s.
4. Equivalently, 1 cP = 1 mPa·s (one millipascal-second), so the cP value IS the mPa·s value.
5. The conversion is exact: 1 poise = 0.1 Pa·s, 1 centipoise = 0.01 poise = 0.001 Pa·s.

Real-World Examples

History of Centipoise and Pascal-second

The poise (P) was named after Jean Léonard Marie Poiseuille (1797-1869), a French physicist and physiologist who studied blood flow through narrow tubes. His work on laminar flow in capillaries led to Poiseuille's law, which relates flow rate to viscosity, pressure, and tube dimensions. The poise was defined as 1 g/(cm·s) in the CGS system. The centipoise (1/100 of a poise) became the preferred practical unit because water — the universal reference fluid — has a viscosity of approximately 1 cP at 20°C. When the SI system was adopted, the equivalent unit became the pascal-second (1 Pa·s = 1 kg/(m·s) = 10 poise). The millipascal-second (mPa·s) was introduced as the SI equivalent of the centipoise: 1 cP = 1 mPa·s exactly. Despite SI adoption, the centipoise remains dominant in industry because of its intuitive scale and decades of established reference data.

Common Mistakes to Avoid

• Confusing centipoise with poise. 1 poise = 100 centipoise = 0.1 Pa·s. If you divide cP by 100 instead of 1,000, you get poise, not Pa·s.
• Mixing up dynamic viscosity (cP, Pa·s) with kinematic viscosity (cSt, m²/s). Dynamic viscosity measures resistance to flow under applied force. Kinematic viscosity is dynamic viscosity divided by density. For water (density = 1 g/cm³), 1 cP = 1 cSt. For other fluids, the values differ.
• Forgetting that viscosity is highly temperature-dependent. Water is 1.0 cP at 20°C but 0.55 cP at 50°C and 1.79 cP at 0°C. Always specify temperature when reporting viscosity.
• Converting cP to mPa·s correctly, then dividing again by 1,000 as if another step were still required. Because 1 cP = 1 mPa·s exactly, you only divide once if you need Pa·s.

Frequently Asked Questions