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Joule per Second to Calorie per Second Converter

Convert J/s to cal/s with our free online power converter.

Quick Answer

1 Joule per Second = 0.239006 cal/s

Formula: Joule per Second × conversion factor = Calorie per Second

Use the calculator below for instant, accurate conversions.

Our Accuracy Guarantee

All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.

Last verified: December 2025Reviewed by: Sam Mathew, Software Engineer

Joule per Second to Calorie per Second Calculator

How to Use the Joule per Second to Calorie per Second Calculator:

  1. Enter the value you want to convert in the 'From' field (Joule per Second).
  2. The converted value in Calorie per Second will appear automatically in the 'To' field.
  3. Use the dropdown menus to select different units within the Power category.
  4. Click the swap button (⇌) to reverse the conversion direction.
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How to Convert Joule per Second to Calorie per Second: Step-by-Step Guide

Converting Joule per Second to Calorie per Second involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

cal/s = J/s × 0.239006

Example Calculation:

1 J/s = 0.239006 cal/s

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

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What is a Joule per Second and a Calorie per Second?

1 J/s = 1 W (exactly, by definition)

SI Definition of Watt: 1 W = 1 J/s = 1 kg⋅m²/s³

1 cal/s = 4.184 W = 0.004184 kW = 0.0056 hp = 14.29 BTU/h

Note: This uses IT (International Table) calorie = 4.1868 J (standard)

Note: The Joule per Second is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Calorie per Second belongs to the imperial/US customary system.

Common Uses and Applications: J/s vs cal/s

Explore the typical applications for both Joule per Second (imperial/US) and Calorie per Second (imperial/US) to understand their common contexts.

Common Uses for J/s

Physics: Fundamental power unit, teaching energy/power relationship. Engineering: Power calculations, energy transfer rates. Scientific: Research papers, technical specifications. Interchangeable: J/s and W used synonymously.

When to Use cal/s

Physics Education: Thermodynamics problems, heat transfer calculations. Older Literature: Pre-SI engineering texts, vintage HVAC data. Scientific: Some chemistry and biology applications. Rarely Modern: Watts or kilocalories per hour preferred today.

Additional Unit Information

About Joule per Second (J/s)

Why is 1 J/s = 1 W exactly?

SI Definition: The watt is defined as one joule per second

Dimensional analysis:

  • Energy: joules (J)
  • Time: seconds (s)
  • Power: energy/time = J/s

Therefore: 1 W ≡ 1 J/s (definitional equality)

Example: 100W device uses 100 J every second

  • 1 second: 100 J used
  • 10 seconds: 1,000 J used
  • 1 hour (3,600s): 360,000 J = 360 kJ = 0.1 kWh

How do I calculate power from energy and time?

Formula: Power (W or J/s) = Energy (J) ÷ Time (s)

Examples:

Charging phone:

  • Battery capacity: 15 Wh = 54,000 J
  • Charging time: 2 hours = 7,200 s
  • Charging power: 54,000 ÷ 7,200 = 7.5 J/s = 7.5 W

Lifting weight:

  • Work done: 500 J (lifting 50 kg by 1 meter)
  • Time taken: 2 seconds
  • Power output: 500 ÷ 2 = 250 J/s = 250 W

Boiling water:

  • Energy needed: 420,000 J (1 liter, 25°C to 100°C)
  • Time: 6 minutes = 360 s
  • Power: 420,000 ÷ 360 = 1,167 J/s = 1,167 W = 1.17 kW

What is the difference between J/s and J?

J (Joule) = Energy (total amount) J/s (Joule per second) = Power (rate of energy transfer)

Analogy:

  • J = distance traveled (miles)
  • J/s = speed (miles per hour)

Example:

  • Energy stored: 10,000 J (battery capacity)
  • Power delivered: 100 J/s (discharge rate)
  • Time to empty: 10,000 ÷ 100 = 100 seconds

Another example:

  • Microwave energy delivered: 600,000 J (to heat food)
  • Microwave power: 1,000 J/s
  • Cooking time: 600,000 ÷ 1,000 = 600 s = 10 minutes

How do I convert between J/s and other power units?

J/s to watts: 1:1 (they're the same)

J/s to other units:

  • kW = J/s ÷ 1,000
  • hp = J/s ÷ 745.7
  • BTU/h = J/s × 3.412

Examples:

  • 1,000 J/s = 1,000 W = 1 kW
  • 745.7 J/s = 745.7 W = 1 hp
  • 100 J/s = 100 W = 341.2 BTU/h

J/s to kW converter → J/s to HP converter →

Why use W instead of J/s if they're identical?

Brevity: "100 watts" vs "100 joules per second" Convention: Industry standard since 1960 Honor: Named after James Watt (inventor, engineer) Clarity: Distinguishes power from energy (avoids "joules per hour" confusion)

In practice: Both acceptable, but "watt" strongly preferred in all applications. Scientific papers use both interchangeably.

About Calorie per Second (cal/s)

How do I convert cal/s to watts or kW?

Formula:

  • W = cal/s × 4.184
  • kW = cal/s × 0.004184

Examples:

  • 1 cal/s = 4.184 W
  • 10 cal/s = 41.84 W
  • 100 cal/s = 418.4 W = 0.418 kW
  • 1,000 cal/s = 4,184 W = 4.184 kW

cal/s to Watts converter → cal/s to kW converter →

What is the difference between cal/s and kcal/h?

cal/s = Small calorie per second (rapid power) kcal/h = Kilocalorie (food Calorie) per hour (slower rate)

Conversion: 1 cal/s = 3.6 kcal/h

Usage:

  • cal/s: Physics, instant power measurements
  • kcal/h: Metabolism, HVAC (some regions)

Example: 70W human at rest

  • As watts: 70 W
  • As cal/s: 16.7 cal/s
  • As kcal/h: 60 kcal/h

How do I calculate heat transfer in cal/s?

Formula: Power (cal/s) = Heat (cal) ÷ Time (s)

Example: Melting ice

  • Ice mass: 100 g
  • Heat needed: 8,000 cal (80 cal/g latent heat)
  • Time: 60 seconds
  • Power: 8,000 ÷ 60 = 133 cal/s = 558 W

Heating water:

  • Water: 1 kg (1,000 g)
  • Temperature rise: 10°C
  • Heat needed: 10,000 cal (1 cal/g⋅°C × 1,000g × 10°C)
  • Time: 100 seconds
  • Power: 10,000 ÷ 100 = 100 cal/s = 418 W

Why use watts instead of cal/s?

SI standard: Watts are internationally standardized (1 W = 1 J/s) Simpler: Avoids cal vs kcal vs Cal confusion Electrical: All electrical power in watts Universal: Works across all energy forms (mechanical, electrical, thermal)

Exception: Some nutrition/metabolism research still uses cal/s or kcal/h for historical consistency.

Conversion Table: Joule per Second to Calorie per Second

Joule per Second (J/s)Calorie per Second (cal/s)
0.50.12
10.239
1.50.359
20.478
51.195
102.39
255.975
5011.95
10023.901
25059.751
500119.503
1,000239.006

People Also Ask

How do I convert Joule per Second to Calorie per Second?

To convert Joule per Second to Calorie per Second, enter the value in Joule per Second in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our power converter page to convert between other units in this category.

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What is the conversion factor from Joule per Second to Calorie per Second?

The conversion factor depends on the specific relationship between Joule per Second and Calorie per Second. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.

Can I convert Calorie per Second back to Joule per Second?

Yes! You can easily convert Calorie per Second back to Joule per Second by using the swap button (⇌) in the calculator above, or by visiting our Calorie per Second to Joule per Second converter page. You can also explore other power conversions on our category page.

Learn more →

What are common uses for Joule per Second and Calorie per Second?

Joule per Second and Calorie per Second are both standard units used in power measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our power converter for more conversion options.

For more power conversion questions, visit our FAQ page or explore our conversion guides.

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Verified Against Authority Standards

All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.

NIST Reference on Constants, Units and Uncertainty

National Institute of Standards and Technology — Fundamental physical constants and unit conversions

BIPM SI Units

Bureau International des Poids et Mesures — International System of Units (SI) definitions and standards

ISO 80000

International Organization for Standardization — Quantities and units international standards series

Last verified: December 3, 2025