Viscosity Converter: Convert cP, P, mPas & More (Free Tool)

You have an oil with a viscosity of 100 cP. Your equipment manual calls for 200 SSU. You need to convert. Viscosity units are confusing. Different industries use different scales.

Viscosity measures how thick a fluid is. Water is thin (low viscosity). Honey is thick (high viscosity). Getting viscosity wrong can damage pumps, affect lubrication, and ruin products.

Today, I give you a free Viscosity Converter.

You enter a value in any unit. The calculator shows the equivalent in all common viscosity units instantly.

The converter handles:

• Centipoise (cP) – dynamic viscosity
• Pascal-second (Pa·s) – SI unit
• Poise (P) – cgs unit
• Centistokes (cSt) – kinematic viscosity
• Saybolt Universal Seconds (SSU)
• Engler degrees (°E)
• Redwood seconds

Let me explain viscosity and how to convert between units.

What is Viscosity? (Simple Explanation)

Viscosity is a fluid’s resistance to flow. Think of it as internal friction.

Two types:

Dynamic (absolute) viscosity – measures resistance when a force is applied. Units: centipoise (cP), poise (P), pascal-second (Pa·s).

Kinematic viscosity – dynamic viscosity divided by density. Units: centistokes (cSt), stokes (St). Used in petroleum industry.

The key relationships:

1 cP = 1 mPas

1 P = 100 cP

1 cP = 0.001 Pa·s

Kinematic viscosity (cSt) = Dynamic viscosity (cP) ÷ Density (g/cm³)

Why This Viscosity Converter Matters

Here is why you need a viscosity converter.

Reason 1: Lubricant selection

Engine oils are rated in SAE grades, which correspond to viscosity ranges at different temperatures. 5W-30, 10W-40 – these numbers come from viscosity.

Reason 2: Pump sizing

Centrifugal pumps perform differently with different viscosities. Higher viscosity = lower flow.

Reason 3: Food and beverage

Ketchup, honey, and sauces have specific viscosity requirements for processing.

Reason 4: Paint and coatings

Spray painting requires specific viscosity. Too thick, and it won’t atomize. Too thin, and it runs.

Reason 5: Medical applications

Blood viscosity affects circulation. Pharmaceutical syrups need consistent viscosity.

The Viscosity Conversion Formulas

Dynamic viscosity:

Kinematic viscosity:

Approximate conversions to SSU (Saybolt Universal Seconds):

SSU = cP × 4.55 (for fluids with density ≈ 0.88 g/cm³)

Note: SSU and Redwood are time-based measures. They depend on both viscosity and density. The conversion is approximate.

LIVE Viscosity Converter

Enter a value in any unit. All other units update instantly.

🔄 Viscosity Converter

Convert between cP, Pa·s, cSt, SSU, and more

📊 Centipoise (cP)

⚡ Pascal-second (Pa·s)

🧪 Poise (P)

🌊 Centistokes (cSt)

⏱️ SSU (Saybolt)

0%

💡 Water viscosity at 20°C: 1.002 cP • Engine oil (SAE 30): ~200 cP at 40°C

📐 1 cP = 0.001 Pa·s = 0.01 P = 1 mPas. For SSU, multiply cP × 4.55 (approx).

How to Use This Viscosity Converter

Step 1: Enter a value in any viscosity unit box
Step 2: All other boxes update instantly
Step 3: Read the converted values in the units you need

The converter handles:

• Centipoise (cP) → Pa·s, Poise, cSt, SSU
• Pascal-second → all others
• And any other combination

Real Examples: Different Scenarios

Example 1: Engine oil (SAE 30)

• Viscosity: 200 cP at 40°C
• Convert to Pa·s: 200 × 0.001 = 0.2 Pa·s
• Convert to SSU: 200 × 4.55 = 910 SSU

Example 2: Water

• Viscosity: 1.002 cP at 20°C
• Convert to Pa·s: 0.001002 Pa·s
• Convert to cSt: 1.002 cSt (density ≈ 1)

Example 3: Honey

• Viscosity: 10,000 cP (approx)
• Convert to Pa·s: 10 Pa·s
• Convert to SSU: 45,500 SSU

Example 4: SAE 5W-30 motor oil

• At 100°C: 9.3-12.5 cSt
• Convert to cP: 9.3-12.5 cP (density ≈ 0.88)
• Convert to SSU: 42-57 SSU

Viscosity Units Reference Table

Viscosity of Common Fluids (at 20°C unless noted)

Dynamic vs. Kinematic Viscosity

Dynamic (absolute) viscosity (μ):

• Measures resistance to flow under force
• Units: cP, Pa·s, P
• Independent of density

Kinematic viscosity (ν):

• Dynamic viscosity divided by density
• Units: cSt, St
• Depends on fluid density

Formula:

ν (cSt) = μ (cP) ÷ ρ (g/cm³)

For water: ρ = 1 g/cm³, so cSt = cP exactly.

For oil: ρ ≈ 0.85-0.95 g/cm³, so cSt ≈ cP × 1.05-1.18.

Saybolt Universal Seconds (SSU)

SSU measures the time for 60 mL of fluid to flow through a calibrated orifice at a specific temperature (100°F or 210°F).

Used for: Petroleum products, heavy oils.

Relationship to cP:

SSU = cP × 4.55 (approximate for many oils)

More accurate formula:

For 40-100 SSU: cP = 0.22 × SSU – (180 ÷ SSU)

For 100+ SSU: cP = 0.225 × SSU – (195 ÷ SSU)

Temperature Effect on Viscosity

Viscosity changes dramatically with temperature.

Liquids: Viscosity decreases as temperature increases.

Gases: Viscosity increases as temperature increases.

Example – SAE 30 oil:

• At 0°C: ≈ 5,000 cP (very thick)
• At 40°C: ≈ 200 cP
• At 100°C: ≈ 11 cP (thin)

Practical impact: Engine oil must flow at cold start (0°C) yet protect at operating temp (100°C). That is why multi-grade oils exist (5W-30, 10W-40).

SAE Viscosity Grades for Engine Oil

5W-30 means: 5W cold rating, 30 hot rating.

Frequently Asked Questions (FAQs)

1. What is the viscosity of water?

1.002 cP at 20°C (room temperature). 0.89 cP at 25°C.

2. How do you convert cP to Pa·s?

Multiply cP by 0.001. 100 cP = 0.1 Pa·s.

3. What is the difference between cP and cSt?

cP is dynamic viscosity. cSt is kinematic viscosity (cP ÷ density). For water, cP ≈ cSt.

4. What is a good viscosity for engine oil?

Depends on your engine and climate. 5W-30 is common for modern cars. Check your owner’s manual.

5. How do you convert SSU to cP?

cP = 0.22 × SSU – (180 ÷ SSU) for SSU < 100. cP = 0.225 × SSU – (195 ÷ SSU) for SSU > 100.

6. Why is honey so viscous?

Honey is mostly sugar. Sugar molecules form strong hydrogen bonds, creating high internal friction.

7. How does temperature affect oil viscosity?

Lower temperature = higher viscosity (thicker). Higher temperature = lower viscosity (thinner).

8. What does “thixotropic” mean?

Viscosity decreases when the fluid is agitated (ketchup, paint). When静止, it thickens.

9. How do you measure viscosity?

Viscometers: capillary tube (Ubbelohde), rotational (Brookfield), falling ball, or Saybolt orifice.

10. What is the viscosity of air?

0.018 cP at 20°C. Increases with temperature.

Common Viscosity Mistakes

Mistake #1: Confusing dynamic and kinematic viscosity

Always check units. cP is dynamic. cSt is kinematic. They are different.

Mistake #2: Ignoring temperature

Viscosity changes with temperature. Always note the temperature when measuring.

Mistake #3: Using SSU without temperature

SSU measurements are always at 100°F or 210°F. Conversions require temperature.

Mistake #4: Mixing up centipoise and poise

1 poise = 100 centipoise. Many older documents use poise.

Mistake #5: Assuming water is 1 cP exactly

Water is 1.002 cP at 20°C. At 0°C, it is 1.79 cP. At 100°C, it is 0.28 cP.

Viscosity Index (VI)

Viscosity Index measures how much viscosity changes with temperature.

• High VI = less change with temperature (good for engine oil)
• Low VI = more change with temperature

Example:

• Paraffinic oils: VI 90-100
• Naphthenic oils: VI 50-70
• Synthetic oils: VI 120-200

Formula (ASTM D2270):

VI = 100 × (L – U) ÷ (L – H)

Where L and H are reference viscosities.

Final Thoughts

Viscosity is a critical fluid property.

My Viscosity Converter gives you:

• Instant conversion between cP, Pa·s, P, cSt, and SSU
• Real-time updates
• Common fluid viscosity references
• SSU conversion formulas

Bookmark this page. Use it for oil selection, pump sizing, and fluid analysis.

The next time you need to convert centipoise to Saybolt seconds or pascal-seconds, you will have the answer.

Disclaimer: This is an educational tool. For critical viscosity measurements, use calibrated instruments at the appropriate temperature.

External Links (Authority Backlinks):

1. Wikipedia – Viscosity{:target=”_blank” rel=”noopener noreferrer”}
2. Wikipedia – Centipoise{:target=”_blank” rel=”noopener noreferrer”}
3. Wikipedia – Saybolt universal viscosity{:target=”_blank” rel=”noopener noreferrer”}

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