Towing Capacity Calculator
Check payload, tongue weight and the real limit on what you can tow.
Please note: A calculated limit, not a certified rating. Always check your vehicle’s actual door-jamb GCWR/GVWR plate and the trailer’s certified weight — modifications, altitude and towing equipment can reduce the real limit below what these figures suggest.
What the Towing Capacity Calculator does
Towing is constrained by two separate ratings, and the smaller one wins. GCWR caps the whole rig; GVWR caps the tow vehicle alone — and because tongue weight lands on the vehicle alongside your passengers and cargo, payload is usually what actually runs out first.
Formula
Payload capacity = GVWR − Curb weightPayload for tongue = Payload capacity − Passengers − CargoLimit by payload = Payload for tongue ÷ Tongue weight %Limit by GCWR = GCWR − Curb − Passengers − Cargo
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Gross combined weight rating (GCWR) | number | Yes | Accepts 0 or more. |
| Gross vehicle weight rating (GVWR) | number | Yes | Accepts 0 or more. |
| Vehicle curb weight | number | Yes | Accepts 0 or more. |
| Weight unit | one of 2 options | Yes | — |
| Passenger weight | number | Optional | Accepts 0 or more. |
| Cargo in the vehicle | number | Optional | Accepts 0 or more. |
| Tongue weight | % | Yes | Conventional trailers run 10–15%; fifth wheels 15–25%. |
| Actual trailer weight | number | Optional | Optional — checks a specific trailer against the limits. Accepts 0 or more. |
How to use it
- Choose Weight unit.
- Enter Gross combined weight rating (GCWR), Gross vehicle weight rating (GVWR), Vehicle curb weight and Tongue weight.
- Optionally add Passenger weight, Cargo in the vehicle and Actual trailer weight.
- Select Calculate.
Worked example
A truck with a 14,000 lb GCWR, 7,000 lb GVWR and 5,500 lb curb weight, carrying 400 lb of passengers and 300 lb of cargo, at 12% tongue weight.
- GCWR
- 14,000 lb
- GVWR
- 7,000 lb
- Curb
- 5,500 lb
- Passengers
- 400 lb
- Cargo
- 300 lb
GCWR allows 7,800 lb, but payload only leaves 800 lb for tongue weight — so at 12% the real limit is 6,667 lb. Payload binds, not GCWR.
Reading the result
- "Tongue weight at the maximum" shows the actual pounds on the hitch at the computed max trailer weight — worth checking against a weight-distribution hitch's own rated capacity, which the maximum-trailer figure alone doesn't reveal.
- When checking a specific trailer, "margin remaining" is most useful read alongside which limit is closest — passing GCWR by a wide margin while barely clearing the payload limit is one bad loading day from being over.
Assumptions and limitations
- Passengers and cargo are entered as flat, one-time figures — the payload-based limit is only valid for the exact load entered, not a standing allowance for whatever gets added later.
- The tongue-weight percentage is a single assumed ratio — the notes say actual percentage should be verified by weighing the loaded trailer, since a poorly loaded one can fall well outside the typical 10–15%/15–25% ranges.
Common mistakes
- Comparing a trailer's weight only against the advertised towing capacity — the notes and FAQ both explain this is almost never the real limit.
- Assuming GVWR and GCWR being satisfied independently is sufficient — both must hold, which is exactly why "your trailer — verdict" checks all three limits together.
Frequently asked questions
Why is my real towing limit lower than the advertised figure?
Advertised capacity assumes a bare vehicle with just a driver. Every passenger and every pound of cargo comes out of the same payload that tongue weight needs.
What tongue weight should I aim for?
10–15% of trailer weight for a conventional hitch, 15–25% for a fifth wheel. Too light and the trailer sways dangerously at speed.