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    Electric Heaters
    Cartridge Insertion Heaters Circulation Heaters Immersion Heaters Air Heaters Flexible Heaters Tubular Heaters Gas Delivery and Exhaust Heaters High-Temperature Heaters Specialty Heaters View All
    Temperature & Process Control
    Multi Loop Controllers Single Loop Controllers Indicators and Alarms Limits and Scanners Operator Interfaces
    Power Control
    Power Controllers Power Switches
    Data Management
    Data Recorders
    Panels & Systems
    WATCONNECT® Control Panels POWERSAFE™ Thermal System
    Sensors
    Thermocouples Resistance Temperature Detectors (RTDs) Fiber Optic Sensing
    man with dual monitors using product selection assistant
    Not Sure? Try Our Digital Product Assistant

    Take the complexity out of product selection with our innovative Digital Product Assistant. Answer a few application questions and our interactive tool will recommend a product from our catalog.

    Launch Assistant

    Services

    thermalwatch thumbnail image of laptop with modern analytics dashboard
    THERMALWATCH™ Intelligent Analytics Solution

    THERMALWATCH leverages our deep understanding of thermal systems to provide secure data integration and management, along with expert analysis, to transform data into valuable information.

    Learn More

    Configure a Product

    vd_
    Watlow SELECT® Visual Designer™

    Quickly configure a product to meet the unique requirements of your application. Instantly access lead times, dimensional drawings, and more - at your own pace. No login required.

    Get Started

    Prefer to talk to a human? Find a Distributor or Sales Office 

    Part Lookup

    Know Your Part Number?

    Enter your part number exactly as marked.

    #
    Tip

    Many parts have lead times, dimensional, drawings, and more available on-demand. Click "Request a Quote" on the search result to access.

    Help Me Choose

    man with dual monitors using product selection assistant
    Not Sure? Try Our Digital Product Assistant

    Take the complexity out of product selection with our innovative Digital Product Assistant. Answer a few application questions and our interactive tool will recommend a product from our catalog.

    Launch Assistant
    Still need help? Locate a Rep Contact Us

    Product Documentation

    Watlow Catalogs Specification Sheets User Manuals Software and Demos Brochures
    CAD Drawings Mobile Applications Watlow Patents Certifications & Approvals
    catalog-ebook
    Try Our Interactive Catalogs

    Click Here

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    icon representing a thermal loop system
    The Thermal Loop

    For Watlow, the underlying concept behind everything we do is that of the thermal loop. Every product we offer, and every project we work on, is ultimately about the creation and control of a thermal loop in an application. 

    Learn More

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    Heat Treatment Energy and Environmental Technologies Life Sciences
    Clinical Equipment Semiconductor Processing Foodservice Equipment

    Electrification

    thumbnails of white papers relating to electrification and decarbonization
    Electrification

    Over 100 years ago, Watlow began designing and manufacturing electric heating elements to replace steam in the shoe industry. We've been electrifying equipment and processes ever since. Wherever thermal is critical, no one is better equipped to help you reach your energy transition goals. Learn why leading companies partner with us.

    Learn More

    Industry 4.0

    thumbnail of industry 4.0 white paper on tablet and print
    The Thermal Loop & Industry 4.0

    Industry 4.0 technology enables the capture and processing of data in real time, both where its generated and where it is needed, to implement effective improvements to industrial processes. Capturing data, though, is not enough. The advantage Watlow® brings to an Industry 4.0 project are its thermal experts, who understand both the important role thermal loop systems play in key applications and industry 4.0 implementations.

    Learn More
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    Shiyi Zhou Joins Watlow® as Regional President for Asia Watlow® Welcomes Klaus Aarestrup as New Regional President of Europe Watlow’s New Large and Extra Large WATCONNECT® Control Panels Maximize Process Uptime with a Small Footprint Watlow’s New PM PLUS® 1/8 DIN PID Controller Watlow® Obtains KGS Certification on Flange and Circulation Heaters Watlow® Completes Acquisition of Eurotherm®
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  1. Tech Tips
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How to Use Watlow’s Wattage Calculator for Accurate Electric Heater Sizing

Popular tags: Wattage Calculation Watt Density Fundamentals System Design

By: Watlow on June 02, 2025

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Need help choosing the right electric heater? Use Watlow’s wattage calculator to determine your BTU/hr and wattage requirements for electric process heating applications. Whether you’re selecting a low wattage heater, sizing electric process heaters, or doing detailed wattage calculations for electric heaters, this tool helps you design an efficient and cost-effective thermal system.

Our easy-to-use calculator ensures accurate heater calculations for various industrial heating applications—helping engineers, OEMs, and manufacturers across the U.S. select the right solution for their processes.

Engineer using wattage calculator

Step-by-step  Guide to Heater Calcutations

If you're a design engineer or process engineer, you know that accurate wattage calculations are critical when selecting electric heaters for manufacturing processes. The Watlow wattage calculator provides a fast and reliable method for performing wattage calculations for electric process heaters, ensuring optimal performance from your heating system.

 

1. Choose Startup Power vs. Continuous Power                                                                                                                                            Start by identifying whether your application needs startup power (for heating up quickly) or continuous power (for maintaining temperature). You can switch between these options based on your process needs.

2. Select “Heat to Raise” or “Heat to Melt”

  • Heat to Raise: Perfect for electric heating applications.

  • Choose your material (from preset options or input a custom one).

  • Enter key data:

  • Volume or weight

  • Specific heat

  • Starting and final temperature

  • Time available to heat

  • Heat to Melt: Ideal for processes involving phase changes (e.g., plastics, metals).

  • Select your material to melt

  • Enter volume and time

  • The calculator will output power requirements in watts

These heater calculations are especially helpful when choosing low wattage heaters for compact or energy-sensitive operations.

3. Factor in Conduction Losses                                                                                                                                                                Your total power requirement should also account for conduction losses, especially in industrial environments. Input these parameters:

  • Heat transfer surface area

  • Material thickness

  • Temperature differential

  • Exposure time

This ensures you accurately size your electric process heater to compensate for thermal losses during operation.

4. Add a Safety Factor

To ensure reliability, our wattage calculator includes a built-in safety factor—defaulted to 20%. You can adjust this value based on your application and margin for unknowns. This is essential for engineers designing robust thermal systems with electric heaters that perform under variable conditions.

"Our calcuator ensures accurate heater calculation for energy-efficient designs, whether you're an OEM or process engineer"

Applications Across Industries

Watlow’s wattage calculator supports engineers in industries like:

  • Food & beverage processing

  • Chemical manufacturing

  • Semiconductors

  • Plastics & packaging

  • Aerospace & defense

 

Whether you're working with low wattage heaters in tight spaces or high-powered electric process heaters, our calculator ensures your system is designed for efficiency and safety.

Start Your Wattage Calculations Today                                                                                                                  Watlow provides expert tools and services to support your heating system design—from heater calculations to power and temperature controllers, sensors, and more.

Try the Watlow Wattage Calculator today to size your electric heater precisely and make informed decisions for your next process heating application.


Related Topics

Wattage Calculation
Watt Density
Fundamentals
System Design
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