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Joule per Second to Kilocalorie per Hour Converter

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

Quick Answer

1 Joule per Second = 0.860421 kcal/h

Formula: Joule per Second × conversion factor = Kilocalorie per Hour

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: February 2026Reviewed by: Sam Mathew, Software Engineer

Joule per Second to Kilocalorie per Hour Calculator

How to Use the Joule per Second to Kilocalorie per Hour Calculator:

  1. Enter the value you want to convert in the 'From' field (Joule per Second).
  2. The converted value in Kilocalorie per Hour 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 Kilocalorie per Hour: Step-by-Step Guide

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

Formula:

kcal/h = J/s × 0.860421

Example Calculation:

1 J/s = 0.860421 kcal/h

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 Kilocalorie per Hour?

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

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

1 kcal/h = 1.163 W = 0.001163 kW = 0.00156 hp = 3.968 BTU/h = 4,184 J/h

Note: Uses food Calorie (Cal) = kilocalorie (kcal) = 1,000 small calories

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 Kilocalorie per Hour belongs to the imperial/US customary system.

Common Uses and Applications: J/s vs kcal/h

Explore the typical applications for both Joule per Second (imperial/US) and Kilocalorie per Hour (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 kcal/h

Metabolism: Basal metabolic rate (BMR), daily energy expenditure. Nutrition: Energy requirements, dietary planning. HVAC: Human body heat load in building calculations (Europe). Sports Science: Exercise energy expenditure, training zones.

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 Kilocalorie per Hour (kcal/h)

How do I convert kcal/h to watts?

Formula: W = kcal/h × 1.163

Examples:

  • 60 kcal/h = 70 W (sleeping)
  • 100 kcal/h = 116 W (sitting)
  • 500 kcal/h = 582 W (running)
  • 1,000 kcal/h = 1,163 W = 1.16 kW

kcal/h to Watts converter →

How do I calculate my basal metabolic rate (BMR)?

Mifflin-St Jeor Equation (most accurate):

Men: BMR (kcal/day) = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) + 5 Women: BMR (kcal/day) = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) - 161

Convert to kcal/h: Divide by 24

Example - 30-year-old male, 80kg, 180cm:

  • BMR = (10 × 80) + (6.25 × 180) - (5 × 30) + 5 = 1,730 kcal/day
  • Hourly rate: 1,730 ÷ 24 = 72 kcal/h = 84 W

Example - 30-year-old female, 65kg, 165cm:

  • BMR = (10 × 65) + (6.25 × 165) - (5 × 30) - 161 = 1,370 kcal/day
  • Hourly rate: 1,370 ÷ 24 = 57 kcal/h = 66 W

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

kcal/h = Kilocalories per hour (large Calorie per hour) cal/s = Calories per second (small calorie per second)

Conversion: 1 cal/s = 3.6 kcal/h

Usage:

  • kcal/h: Metabolism, nutrition (aligns with daily calorie counts)
  • cal/s: Physics, thermodynamics

Example: 100W power

  • As watts: 100 W
  • As kcal/h: 86 kcal/h
  • As cal/s: 24 cal/s

How many kcal/h do I burn exercising?

MET (Metabolic Equivalent) method:

Formula: kcal/h = MET × weight(kg) × 1.05

Common MET values:

  • Sleeping: 0.9 METs
  • Sitting: 1.0 METs
  • Walking (3 mph): 3.5 METs
  • Jogging (5 mph): 8.0 METs
  • Running (7 mph): 11.5 METs
  • Cycling (moderate): 8.0 METs
  • Swimming (moderate): 8.0 METs

Example - 70kg person running at 7 mph:

  • kcal/h = 11.5 × 70 × 1.05 = 845 kcal/h = 982 W

Example - 70kg person walking at 3 mph:

  • kcal/h = 3.5 × 70 × 1.05 = 257 kcal/h = 299 W

Why does HVAC use kcal/h in some countries?

Historical: European HVAC tradition used kcal/h before SI adoption Body heat: Natural unit for human heat output (matches food calories) Transition: Many European countries now use watts Mixed practice: Some European standards still reference kcal/h

Conversion for HVAC:

  • 1 person (seated): 100 kcal/h = 116 W
  • Conference room (20 people): 2,000 kcal/h = 2,320 W = 2.32 kW
  • Gym (50 people, active): 20,000 kcal/h = 23,200 W = 23.2 kW

Modern practice: Most HVAC calculations now in watts or BTU/h.

Conversion Table: Joule per Second to Kilocalorie per Hour

Joule per Second (J/s)Kilocalorie per Hour (kcal/h)
0.50.43
10.86
1.51.291
21.721
54.302
108.604
2521.511
5043.021
10086.042
250215.105
500430.21
1,000860.421

People Also Ask

How do I convert Joule per Second to Kilocalorie per Hour?

To convert Joule per Second to Kilocalorie per Hour, 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 Kilocalorie per Hour?

The conversion factor depends on the specific relationship between Joule per Second and Kilocalorie per Hour. 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 Kilocalorie per Hour back to Joule per Second?

Yes! You can easily convert Kilocalorie per Hour back to Joule per Second by using the swap button (⇌) in the calculator above, or by visiting our Kilocalorie per Hour 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 Kilocalorie per Hour?

Joule per Second and Kilocalorie per Hour 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: February 19, 2026