Speak with an expert
Vunked
ShopAboutBlogContact
Build Your System
Build Your System
VUNKED

Simplifying campervan electrics. Design, build, and power your adventure.

hello@vunked.co.uk

Quick Links

  • Systems
  • About
  • Blog
  • Contact
  • Configurator
  • Solar Panel Kits
  • Leisure Battery Kits
  • Victron Campervan Kits

Legal

  • Terms & Conditions
  • Privacy Policy
  • Returns & Refunds
  • Cookies Policy
© 2026 Vunked. All rights reserved.
What size inverter?
  1. Home
  2. /
  3. Blog
  4. /
  5. What Inverter Size Do I Need

What Inverter Size Do I Need

What size inverter?
  1. Home
  2. /
  3. Blog
  4. /
  5. What Inverter Size Do I Need

What Inverter Size Do I Need

Campervan Electrics
By Ross Deacon21 Nov 20225 min read
Let's set the scene...

You're planning your tiny home conversion, umming and ahing about what campervan inverter size you need. We get it, it can feel overwhelming to understand what's right for you and the last thing you want is to run out of power.

The good news is, we're here to help with this handy one stop guide to choose the right size of inverter to keep your bread toasting and microwave turning, all day long. Keep reading.

In this blog, we will look at:

  • Factors that influence your campervan inverter size
  • How to calculate your overall appliances usage
  • Introducing you to our handy Inverter Size Calculator
  • Background information on inverters
  • What is a watt? (Sounds daft but it's very important to understand)

If you would like to skip the reading, you can go straight to our Inverter Size Calculator.

What Size of Inverter Do I Need?

Inverter size is directly related to which 230V appliances you want to use off grid in your campervan. You can size your inverter right now by following 3 steps:

Step 1 - Create a list of all the 230V appliances you want to use with your campervan electrical system. Next to each appliance, write down the watts (W) rating of that appliance.

Step 2 - Find out the wattage of the highest rated appliance that you plan to use and add a 20% buffer. Write down this value.

Step 3 - Take a total wattage of all your 230V appliances. Write down this value.

QUICK TIP - The Watts (W) rating of most appliances can be found on a sticker on the appliance, charger/power cable or product website page. See a list of common appliances and their wattage below.

What next?

Once all the steps have been completed, you will have two values.

Value 1: Based upon your highest rated appliance

Value 2: Based upon the total wattage of all your appliances

These two values will inform you on what inverter size you need for your campervan, giving you two options.

Now, lets run through an example…

Example: What Size of Inverter Do I Need?

To calculate what Inverter size you need for your campervan, follow our example below or alternatively use our Campervan Inverter Size Calculator.

In this example we will be looking to use the following 230V appliances off-grid:

  • Hair straighteners - 150W
  • Laptop charger - 100W
  • Blender - 500W
  • E-bike - 600W
How To Size A Campervan Inverter
Your Options

Following this example will give you two powers (W) to size your campervan inverter. Which one you pick depends on how you wish to use your appliances:

Inverter size 1 - Size your inverter using the highest rated appliance if you only need to use one 230V appliance at a time. Shown in step 2. 

Inverter size 2 - Size your inverter using the total wattage of your appliances if you want to have unrestricted access to your 230V appliances. Shown in step 3. 

We build our kits using Victron components. The Victron Energy Inverter specifications can be found on their website.

Top Tip

Important note: Victron Energy names their inverters using the power supplied under ideal conditions (VA). In reality, the real power output is slightly less than the name. For example, the 800VA Victron Inverter will provide 650W at 25℃.

Using One Appliance Vs Using All Your 230V Appliances at a Time

Using One Appliance at a Time

We recommend sizing your inverter using the highest rated appliances, plus adding a 20% buffer if you would like to keep costs down and want to get as much time off grid as you can.

Advantages:

  • Keep costs to a minimum by using a smaller inverter
  • By using less appliances your energy consumption will be lower, giving you longer off grid

Disadvantages:

  • You will have to keep an eye on what 230V appliances you run - if you try to draw more power than your system can handle you will likely blow a fuse

Using All Your Appliances at Once

We recommend sizing your inverter using the total wattage of all your appliances if you are happy spending a bit more money and want to have unrestricted use of your 230V appliances.

Advantages:

  • Able to use all your 230V appliances at once

Disadvantages:

  • Your larger Inverter will be more expensive
  • Your system will draw more power so will require a larger battery or charging capabilities to stay off grid
  • As your system is drawing more power you will need thicker cables to handle this which can increase the cost slightly

Calculator: Campervan Inverter Size

Use our handy calculator to find out what campervan inverter size you need straight away. Choose the 230V appliances you want to use in your campervan and we will take care of the rest.

The calculator results will contain a link that takes you directly to an Inverter system that suits your style of adventure. Our Inverter systems come with all the wires, consumer units, fuses, lugs and heat-shrink you need to install in your campervan.

Alternatively, you can view our Victron Phoenix Inverters as stand alone items.

[convertcalculator id="yDM9aTYgtJMACmyhC"]

Learning Zone: Inverters

What is an Inverter?

An inverter is a device that transforms DC voltage into AC voltage. Campervan leisure batteries store energy as a DC voltage, either 12, 24V or sometimes 48V. Your appliances that have a UK 3 pin plug (most of them) require 230V AC voltage to run - we call these 230V appliances. An inverter lets you power larger appliances on your adventure. If you want to take a laptop charger, hair straighteners or even a kettle for a cup of tea on those crisp mornings - you will want an inverter.

What is a watt (W)?

The watt (W) is a universal measurement for power - more specifically it is energy per unit of time. For those of you that remember physics at school, 1 watt is the equivalent of one joule of energy per second.

All electrical appliances will have a wattage rating. This is an important factor to consider when planning your van build. By thinking about what appliances you want to use in your van, we can help you build a campervan electrical system that is suited for your style of adventure.

Build your own Campervan ELectrical system

Build: Inverter Systems

Worried about wire and fuse sizes? Want your Campervan Electrical System to be designed by an expert? Look no durther. All our Inverter Systems come with all the wires, fuses, consumer units, lugs and heatshrink you need to install in your campervan...

If you already have all the extras, you can buy a Victron Energy Phoenix Inverter own its own.

250VA Victron Phoenix Inverter System

250VA Victron Phoenix Inverter System

£209.99

375VA Victron Phoenix Inverter System

375VA Victron Phoenix Inverter System

£229.99

500VA Victron Phoenix Inverter System

500VA Victron Phoenix Inverter System

£279.99

800VA Victron Phoenix Inverter System

800VA Victron Phoenix Inverter System

£429.99

1200VA Victron Phoenix Inverter System

1200VA Victron Phoenix Inverter System

£509.99

1600VA Victron Phoenix Smart Inverter System

1600VA Victron Phoenix Smart Inverter System

£899.99

About the author

Ross Deacon, Co-founder of Vunked
Ross Deacon

Co-founder · MSc Aerospace Engineering, University of Glasgow

Ross Deacon is co-founder of Vunked and leads platform architecture, simulation, and system modelling. He holds an MSc in Aerospace Engineering from University of Glasgow and spent five years as a Systems Design Engineer at Thales, working across both Crawley and Glasgow offices.

System DesignSimulationModelling
Read more about Ross →
Complete Vunked Victron campervan electrical system

Free Online Tool

Expertly Designed Campervan Electrics In Minutes

Use our free configurator to design a complete electrical system tailored to your campervan.

Build Your System

Read next

What Is a Busbar and Do You Need One? + How To Size for a Campervan

You've probably heard that busbars are a must have for managing complex campervan electrical systems, but what is a busbar? And do you really need one?

11 Sep 2025
Campervan 12v fridge cutaway diagram

Is The Campervan 12V Fridge Still King? Ultimate Guide + Power Use Explained

The humble 12v fridge remains a stalwart choice for vanlifers, but are they still the best? See our unbiased recommendations + power usage explained.

9 Sep 2025
What is MPPT vs PWM comparison

What is MPPT: A Complete Guide to Campervan Solar Charge Controllers

Reliable solar power is a must for off-grid campervan adventures. Our complete guide covers what is MPPT, how it compares to PWM, and whether you need it.

5 Aug 2025
Woman and dog next to a campervan at the foot of a mountain

The Best Campervan Electrical Systems for Every Type of Vanlifer

Choosing the right campervan electrical system depends entirely on your lifestyle and preferences. A digital nomad needs consistent off-grid power to work anywhere. A part-time traveller might only need weekend reliability. And if you're retired or work seasonally, you'll want comfort and efficiency without the need for constant maintenance. Your van's power system will largely dictate how you live and travel. This guide breaks down the best electrical setups for various types of vanlifers, inc

10 Jul 2025
Build My System