⚖️ Axle Weights (lbs)
🌉 Bridge Formula (outer axle group)
Weight Status
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Gross Weight
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Legal Gross Limit
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Margin
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Bridge Formula Max
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Frequently Asked Questions
Is the Axle Weight & Bridge Formula Calculator free to use?
Yes — completely free with no account required. All QuicklyFig calculators are funded by display advertising so you never pay to use them.
What is the Federal Bridge Formula?
The Federal Bridge Gross Weight Formula is W = 500 × ((L × N) ÷ (N − 1) + 12N + 36), where W is the maximum legal weight on a group of axles, L is the distance in feet between the outer axles of the group, and N is the number of axles in that group. It works alongside the federal Interstate limits of 20,000 lb per single axle, 34,000 lb per tandem, and 80,000 lb gross.
My gross weight is legal but one axle group is overweight — what do I do?
Slide your trailer tandems or fifth wheel to shift weight between axle groups. Moving the tandems rearward shifts weight off the drive axles and onto the trailer axles (and forward does the reverse). Your total gross stays the same, but you can bring an individual group back under its limit. Re-weigh on a certified CAT scale to confirm before a DOT inspection.