The Motorhome Payload Calculator lets you enter your vehicle's weight limits and tick off everything you're carrying, giving you a real-time figure for how much payload you have left. If you already understand Payload, they get straight to the motorhome payload calculator.. there's a link to the calculator here. Though you will need to be a registered member of MotorhomeFun to use it, you can register for free.
I If you are not quite sure about what payload is or how it is calculated, read this explanatory text first before using the calculator.
What Is Motorhome Payload?
Motorhome payload is the total weight you are legally allowed to add to your vehicle above its Mass in Running Order (MIRO). It is calculated as:
Payload = MAM minus MIRO
For example, a motorhome with a MAM of 3,500kg and a MIRO of 3,000kg has a payload allowance of 500kg. That 500kg must cover every passenger, every item of clothing, all food and water, gas bottles, bikes, tools, bedding, pets and everything else you put in the vehicle.
What Is MAM on a Motorhome?
MAM stands for Maximum Authorised Mass, which is the maximum legal weight of the motorhome when fully loaded on the road. It is also called Gross Vehicle Weight (GVW). You can find your MAM on your V5C registration document or on the manufacturer's plate, which is usually located inside the driver's door frame.
What Is MIRO on a Motorhome?
MIRO stands for Mass in Running Order. It is the manufacturer's stated weight of the motorhome as it leaves the factory, including standard fluids and a 75kg allowance for the driver. MIRO figures are published in the manufacturer's handbook or sales brochure and do not appear on the V5C.
Are Motorhome MIRO Figures Accurate?
No. Manufacturer MIRO figures are estimates and should be treated with caution. In practice, many motorhomes weigh more than their quoted MIRO when they leave the dealership, particularly if factory-fitted options have been added. The only way to get an accurate unladen weight is to put the vehicle on a weighbridge.
At MotorhomeFun, we call this the forecourt weight: the actual weight of the motorhome as driven away. Using the forecourt weight instead of the manufacturer's MIRO gives you a true picture of your real payload. Many owners discover their actual payload is significantly less than they expected.
How Much Payload Does a Typical Motorhome Have?
A typical 3,500kg coachbuilt motorhome has a manufacturer's quoted payload of between 350kg and 650kg. However, once the vehicle is weighed accurately at a weighbridge, the real payload is often at the lower end of that range and sometimes less. This is important because:
- Two adults weigh approximately 150kg combined
- Fresh water tank adds 20kg per 20 litres
- Two bikes on a rear rack add 35 to 50kg
- A dog, bedding, food, clothing, gas and tools can easily account for another 150 to 200kg
It is entirely possible for a couple with bikes, a dog and a full water tank to use 400kg of payload before they have unpacked a single bag.
What Happens If a Motorhome Is Overloaded?
Driving an overloaded motorhome is illegal. The consequences include:
- Fines of up to £300 per axle at a roadside check
- Invalidated insurance some policies have a clause voiding cover if the vehicle exceeds its MAM at the time of an incident
- Impounded vehicle as an officer can prohibit the vehicle from moving until weight is reduced
- Compromised safety as overloading affects braking distances, tyre integrity, steering response and stability
How to Use the Motorhome Payload Calculator
- Enter your MAM from your V5C or door plate
- Enter your MIRO or weighbridge (forecourt) weight from your handbook, or better still a weighbridge ticket
- Tick every item you are carrying and work through the categories
- Watch the gauge as your remaining payload updates in real time
All weights in the motorhome payload calculator are editable. Click any kg figure to enter the actual weight for that item. A custom items section lets you add anything not already listed.
The payload gauge stays fixed at the top of the screen as you scroll, turning orange as you approach your limit and red if you go over.
The MotorhomeFun Payload Calculator is a Free tool created by MotorhomeFun You need to be a free registered member to use it. You can find the calculator here.
If you experience any issues with or would like to discuss anything about this calculator, you can do that here. Motorhome Payload Calculator Discussion.