Kerb weight is the weight of your vehicle when it’s ready to drive, including fuel and essential fluids, but without passengers, luggage, or cargo. Gross Vehicle Weight (GVW), also known as Maximum Authorised Mass (MAM), is the maximum safe and legal weight of the vehicle when fully loaded. The difference between the two figures determines how much weight your vehicle can carry.
If you’ve ever looked at vehicle specifications, towing limits, or payload allowances, you’ve probably come across these terms. Understanding the difference can help you stay within legal limits, avoid overloading your vehicle, and make informed decisions when carrying passengers, equipment, or luggage.
Understanding Vehicle Weight Terminology
What Is Kerb Weight?
Kerb weight is the weight of a vehicle when it’s ready to be driven on the road. This generally includes fuel and other essential fluids but does not include passengers, cargo, or additional loads.
Think of kerb weight as the vehicle’s starting weight before you add anything extra.
For example, a family car might have a kerb weight of 1,500kg. Before anyone gets in or any bags are loaded, that is roughly what the vehicle weighs.
What Is Gross Vehicle Weight (GVW)?
Gross Vehicle Weight (GVW) is the maximum weight a vehicle is allowed to weigh when fully loaded. This includes:
- The vehicle itself
- The driver
- Passengers
- Fuel
- Luggage
- Tools
- Equipment
- Any other cargo carried in the vehicle
GVW is also commonly referred to as Maximum Authorised Mass (MAM) or permissible maximum weight. Manufacturers set this limit to ensure the vehicle can be operated safely on the road. GOV.UK’s vehicle weights explained guide provides further information on GVW, MAM and gross train weight.
Kerb Weight vs Gross Vehicle Weight at a Glance
| Feature | Kerb Weight | Gross Vehicle Weight (GVW) |
| Includes fuel and fluids? | Yes | Yes |
| Includes passengers? | No | Yes |
| Includes luggage or cargo? | No | Yes |
| Indicates vehicle’s base weight? | Yes | No |
| Represents legal maximum weight? | No | Yes |
| Used to calculate payload? | Yes | Yes |
In simple terms, kerb weight tells you what the vehicle weighs before loading it, while GVW tells you the maximum weight it can safely and legally reach once loaded.
Why the Difference Matters
Staying Within Legal Limits
Driving an overloaded vehicle can create safety risks and may result in enforcement action if weight limits are exceeded. Vehicle manufacturers specify GVW limits to help ensure vehicles remain safe to operate. The DVSA’s guidance on maximum vehicle weights explains the weight limits that apply to vehicles operating on UK roads.
Protecting Vehicle Safety
Exceeding your vehicle’s weight limit can affect:
- Braking performance
- Tyre wear
- Suspension components
- Vehicle handling and stability
Even if you only exceed the limit slightly, the additional weight can impact how the vehicle performs.
Choosing the Right Vehicle
Understanding vehicle weight limits can also help when selecting a car or van.
For example:
- A growing family may need more payload capacity for passengers and luggage.
- A tradesperson may need sufficient capacity for tools and equipment.
- A courier may need to understand load limits before transporting goods.
If you’re planning to purchase a van, it’s worth checking kerb weight, GVW and payload figures alongside the other considerations covered in our guide to buying a used van in the UK.
How to Calculate Your Vehicle’s Payload
Payload refers to the weight your vehicle can carry.
The Formula
Payload = Gross Vehicle Weight (GVW) − Kerb Weight
Example
Let’s say your vehicle has:
- Kerb weight: 1,600kg
- GVW: 2,100kg
The calculation would be:
2,100kg − 1,600kg = 500kg payload
That 500kg allowance must cover everything added to the vehicle, including:
- Driver
- Passengers
- Luggage
- Tools
- Equipment
- Accessories
This is why payload can disappear more quickly than many drivers realise. If you regularly carry tools, stock or equipment, it’s important to understand your vehicle’s payload limits and the risks of exceeding them. Read our guide on what happens if you overload a van for more information.
Where Can You Find Your Vehicle’s Weight Information?
Check the VIN Plate
Many vehicles display weight information on the Vehicle Identification Number (VIN) plate, which is often located:
- Inside the driver’s door frame
- On a door pillar
- Under the bonnet
Check the Owner’s Manual
The manufacturer’s handbook usually contains information about:
- Kerb weight
- GVW
- Payload capacity
- Towing limits
Check Manufacturer Specifications
If you no longer have the handbook, the manufacturer’s website often provides official vehicle specifications.
Check Your Vehicle Documentation
Some weight information may also be available through vehicle documentation, although the level of detail varies depending on the vehicle and manufacturer.
Vehicle Weight and Towing
When towing a trailer or caravan, weight calculations become even more important.
Why Kerb Weight Matters
Kerb weight is often used when assessing towing suitability and vehicle stability.
Why GVW Matters
Even when towing, the vehicle itself must remain within its GVW limit. Passengers, luggage, and trailer nose weight can all contribute towards the vehicle’s overall loaded weight.
What Is Gross Train Weight (GTW)?
Gross Train Weight (GTW), sometimes called Gross Combination Weight (GCW), is the combined weight of the towing vehicle, trailer, and load. This figure is separate from GVW and is usually shown on the vehicle plate.
If you’re planning to tow regularly, it’s important to understand all relevant weight limits rather than focusing on a single figure.
Common Mistakes Drivers Make
Assuming Payload Only Means Cargo
Payload includes much more than boxes or equipment. Drivers, passengers, and luggage are all part of the total.
Forgetting About Accessories
Items such as those listed below can all contribute towards the vehicle’s weight:
- Roof boxes
- Bike racks
- Additional equipment
- Work tools
Remember to factor in the weight of fitted and removable accessories before loading passengers or cargo. Accounting for these additions will give you a more accurate picture of your remaining payload capacity.
Confusing Kerb Weight With GVW
This is one of the most common misunderstandings. Kerb weight is not the maximum weight your vehicle can carry. GVW is the limit that must not be exceeded.
Overlooking Passenger Weight
A family holiday with four passengers and a full boot can add a significant amount of weight to a vehicle before any additional equipment is loaded.
Quick Vehicle Loading Checklist
Before setting off, consider the following:
- Check your vehicle’s GVW
- Know your available payload capacity
- Include passenger weight in your calculations
- Account for luggage, tools, and equipment
- Consider accessories such as roof boxes or bike racks
- Review towing limits separately if towing a trailer or caravan
Frequently Asked Questions
Is kerb weight the same as gross vehicle weight?
No. Kerb weight is the vehicle’s weight before passengers and cargo are added. GVW is the maximum permitted weight when the vehicle is fully loaded.
Is GVW the same as MAM?
In many cases, yes. GOV.UK explains that Maximum Authorised Mass (MAM) is also known as Gross Vehicle Weight (GVW) or permissible maximum weight.
Can passengers count towards payload?
Yes. Everyone travelling in the vehicle contributes towards the vehicle’s overall loaded weight.
How do I know if my vehicle is overloaded?
You will need to compare the vehicle’s actual loaded weight with its GVW. If you’re unsure, check the VIN plate and manufacturer guidance.
Does towing affect vehicle weight calculations?
Yes. Towing introduces additional weight considerations, including GVW and Gross Train Weight limits.
Does vehicle weight affect insurance?
Vehicle weight itself is not usually something drivers think about when arranging van insurance, but factors such as vehicle type, usage, modifications, and payload requirements can all be relevant. If you’re unsure, it’s always worth checking your policy documentation or speaking with your insurer.
Applying Vehicle Weight Limits in Practice
Understanding the difference between kerb weight and gross vehicle weight is simpler than it first appears. Kerb weight tells you what the vehicle weighs before loading it, while GVW tells you the maximum weight it can safely and legally reach once loaded.
Whether you’re carrying tools for work, packing for a family holiday, or preparing to tow a trailer, knowing these figures can help you stay within vehicle limits and travel more confidently. If you’re unsure about your vehicle’s specific limits, check the VIN plate, owner’s manual, or manufacturer guidance before loading up.