Towing Capacity Calculator
Work out the maximum trailer weight a vehicle can legally and safely tow.
Tongue weight is the number that causes accidents
A trailer should carry 10–15% of its weight on the hitch. Too little and it sways at speed, which is the classic caravan accident; too much and it lifts the front wheels and ruins steering. Load heavy items over the trailer axle, slightly forward of centre.
What this page needs from you
This page asks for gross combined weight rating in kg, vehicle kerb weight in kg and passengers and cargo in kg. From those it returns maximum trailer weight in kg, together with in pounds, recommended tongue weight (10-15%), payload used and safety margin at 80%. Every figure updates as you type, and nothing you enter leaves your browser.
Rounding, and when it matters
Nothing is rounded internally; only the display is. That keeps the arithmetic exact and means the figures agree with a spreadsheet, but it also means a result shown to two decimals may carry more precision than the inputs deserve. If you measured something to the nearest whole unit, do not read meaning into the digits after the point.
When to use something else
Every calculation is a model, and a model is a deliberate simplification. Where the answer will drive a decision that is expensive or hard to reverse, use this to understand the shape of the problem and then confirm the specifics with someone who can see details this page cannot.
The formula
Max trailer = GCWR − kerb weight − passengers and cargo
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Towing Capacity Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Towing Capacity Calculator — frequently asked questions
Is this towing capacity calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the towing capacity calculator.
- towing capacity calculator
- tow rating
- gcwr calculator
- trailer weight calculator
- how much can i tow
About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed September 10, 2026 · Calculation runs client-side · No data collected · Report an error