Axle Position Calculater

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TRAILER AXLE POSITION & BALANCE CALCULATOR

Professional trailer axle-position and balance calculator with guided inputs, live engineering results and a printable workshop build sheet

GUIDED TRAILER DESIGN CALCULATOR
Step 1 of 7 — Trailer Dimensions 0% Complete
✎ Step 1 — Trailer Dimensions
▰
Length of the flat deck / tray
mm
✣
Horizontal distance to towball centre
mm
⚖
Completed empty trailer weight, including axle, wheels, guards, ramps and fixed equipment
kg
◎
Distance from the front edge of the tray. Use an estimate if the empty-trailer CG has not been measured
mm
%
Adjustable design target. Default is 10%
%
ⓘUse the tray length for the flat deck only. Measure drawbar length from the front edge of the tray to the towball centre.
✓Live calculation: every Step 1 value updates the cargo totals, engineering results, trailer diagram and workshop build sheet automatically.
Measurement Guide — Top-View Measurements

Tray length is measured along the flat deck. Drawbar length is measured horizontally from the front edge of the tray to the towball centre.

TRAY / DECK TRAY LENGTH Front edge of tray Towball centre DRAWBAR LENGTH
▣ Step 2 — Trailer Type & Axle Configuration

What does “Apply Recommended Defaults” do?

It sets a suggested towball-weight target for the selected trailer type and, once tray length is entered, places the empty-trailer centre of gravity at a sensible starting position.

Use it when starting a new design or when you want a safe baseline to refine.

Leave it unchanged when your trailer has already been engineered, measured or built and you need to preserve its known tare-CG or target value.

Nothing is locked: you can review and edit every applied value afterwards.

Box / General Purpose Trailer

A versatile general-purpose layout. Keep dense cargo low and close to the axle group, with sufficient positive towball load.

Suggested target10.0%
Suggested tare CG50% of tray
Calculation datumAxle-group centre
✥ Step 3 — Cargo Input Method & Visual Builder

Cargo calculation mode

Add trailer components

Trailer tray — drag components from front to rear

Click a component to edit its exact weight and position. Position is measured from the front edge of the tray to the component centre.

FRONT / TOWBALLREAR
Complete Step 1 and enter a tray length before adding components.
Tray length: 0 mm
Select a component from the library. Its setup controls will appear here before it is added.
Select a component above to begin.
Selected component to add
Complete Step 1 and enter a tray length before adding components.
ⓘSelect a component type, confirm its weight and starting position, then click Add Component. Component weights are assigned automatically to Quarter 1–4 from their position. The engineering calculation still uses each component’s exact position, so weight is never counted twice.
Components0
Builder cargo0 kg
Builder cargo CG0 mm
Active cargo source4 Quarters
⚖ Step 4 — Load Distribution Summary
✓ Automatically calculated from the components placed in Step 3.
Review the complete tray load distribution before continuing.
The tray is divided into four equal sections measured from the front edge of the tray to the rear edge.
Front Quarter0% - 25%Tray length required
kg
Quarter 225% - 50%Tray length required
kg
Quarter 350% - 75%Tray length required
kg
Rear Quarter75% - 100%Tray length required
kg
Trailer Tare0 kg
Cargo Weight0 kg
Estimated ATM0 kg
Cargo CG0 mm
Combined CG0 mm
Recommended Axle0 mm
Towball Load0 kg
Towball Percentage0.0%
Review only — engineering calculations remain controlled by the canonical engine.
👁 Step 5 — Live Engineering Diagram
Tray0 mm
Drawbar0 mm
Cargo CG0 mm
Combined CG0 mm
Axle centre0 mm
Towball0.0%
Q1 · 0 kgFRONT 0–25%
Q2 · 0 kg25–50%
Q3 · 0 kg50–75%
Q4 · 0 kgREAR 75–100%
025%50%75%100%
FRONT / TOWBALL
REAR
AXLE-GROUP CENTRE
Combined CG
0 mm
Recommended axle position
0 mm
Cargo CG · 0 mm
Combined CG · 0 mm
Recommended axle · 0 mm
Tray length
0 mm
Drawbar length
0 mm
Waiting for valid engineering inputs.Step 5 ↔ Step 6
○ Engineering waiting
○ Quarter totals waiting
○ Diagram waiting
○ Axle waiting
○ Towball waiting
○ Ratings optional
Cargo CG0 mm
Combined CG0 mm
Recommended Axle0 mm
Towball0 kg
GTM0 kg
ATM0 kg
StatusWaiting
💡 Technical side elevation: towball/front is on the left and rear is on the right. Axle, cargo CG and combined CG positions are measured from the front edge of the tray.
✓ Step 6 — Engineering Results
✓ Engineering engine self-check passed: cargo moments, combined CG, axle position, towball load, ATM and GTM identities verified against known-answer cases.
◎
Cargo centre of gravityFrom front of tray
0 mm
◉
Combined centre of gravityTrailer tare plus cargo
0 mm
⚙
Recommended axle positionMeasured from front of tray to axle or axle-group centre
0 mm
🛡
Estimated towball loadAt the selected target percentage
0 kg0.0%
♙
Estimated GTM / axle loadTotal supported by the axle or axle group
0 kg
Enter trailer dimensions and weight information to calculate the Stage 1 engineering estimate.

⚖ Typical 60/40 Axle Position (Comparison Only)

60% tray position0 mm
Resulting towball load0 kg

Resulting towball percentage: 0.0%

🛡 Manufacturer Design Ratings
kg
kg
kg
Calculated ATM / Rating0 / Not set
Calculated GTM / Rating0 / Not set
Towball load / Limit0 / Not set
Awaiting manufacturer or certified design ratings. Presets are starting values only and must be verified for the actual trailer components and certification.
Engineering estimate: Include all fixed trailer components in tare weight and use a realistic empty-trailer centre of gravity. Verify final ATM, GTM and towball load on the completed trailer using suitable scales or a weighbridge.
▤ Step 7 — Printable Workshop Build Sheet

Job, customer and compliance information

kg
kg
kg
Enter trailer ratings to compare the calculated ATM, GTM and towball load with the intended design limits.
ⓘUse your browser's Print command and select “Save as PDF” for a workshop-ready digital build sheet.

Live workshop document preview

COFFS METAL WORKS

Trailer Axle Position & Balance — Workshop Build Sheet

Job: —
Date: —
Customer: —
Model: —
Trailer configuration
Trailer type—
Axle configuration—
Tray length0 mm
Drawbar length0 mm
Trailer tare0 kg
Tare centre of gravity0 mm
Cargo method4 Quarters
Target towball load10.0%
Engineering result
Cargo weight0 kg
Cargo CG0 mm
Combined CG0 mm
Axle / group centre0 mm
Estimated ATM0 kg
Estimated GTM0 kg
Towball load0 kg
Towball percentage0.0%
Enter trailer dimensions and weights to calculate the build specification.
Cargo / component schedule
Item / zone Weight Position from tray front Notes
No cargo entered.
Design ratings
Rated ATMNot entered
Rated GTMNot entered
Towball limitNot entered
Rating assessmentPending
Workshop notes
No workshop notes entered.
Fabrication and verification checklist
Axle or axle-group centre marked from tray front datum
Left and right axle measurements confirmed square
Suspension, axle, wheel and tyre ratings verified
Drawbar, chassis and coupling ratings verified
Brake requirements and components verified
Fixed equipment included in tare calculation
Completed trailer tare and CG checked
Loaded ATM, GTM and towball weight measured
Fabricator / Technician
Checked by
Completion date
Engineering estimate only. The calculated axle position is measured from the front edge of the tray to the single axle centre or the centre of the complete axle group. Final construction must comply with applicable regulations, component ratings and professional engineering requirements. Verify the completed trailer using suitable scales or a weighbridge.
✓ Design Review & Approval Centre
Trailer type—
Axle configuration—
Tray length0 mm
Drawbar length0 mm
Trailer tare0 kg
Cargo method4 Quarters
Cargo weight0 kg
Target towball load10.0%
Complete the guided workflow to generate the final design review.
ⓘ Guided workflow • Measurements in millimetres (mm) and kilograms (kg) ⟳ Adjust inputs to see how axle position changes