How the Axle Weight Calculator Works

Regulatory basis

Commercial vehicle weight limits in Canada are set province-by-province under each province's Highway Traffic Act or equivalent. There is no single federal weight limit for provincial highways — Transport Canada sets limits for federal Crown roads and international border crossings, but day-to-day trucking compliance is governed by the province where the truck is operating.

The regulations embedded in this calculator are sourced from each province's current highway authority:

Your inputs — what each field means

Axle configurations — what they mean

The calculation — step by step

1. Look up province data. The calculator reads the embedded data table for the selected province, which includes: normal limits for each axle type (single, tandem, tridem, quad), the spring multiplier, and the spring restriction months.
2. Select the applicable limit:
   normal limit = provincial table value for selected axle type
3. Apply spring restriction if selected:
   spring limit = round(normal limit × spring multiplier)
   Example: Ontario tandem normal limit = 18,000 kg; spring multiplier = 0.90 → spring limit = 16,200 kg.
4. Return active limit: If spring restriction is selected, the spring limit is shown as the active limit. Otherwise, the normal limit applies.

Spring restrictions — how they work

Spring load restrictions are imposed every year during the spring thaw, when frost leaves the ground. As the ground thaws, sub-base layers become saturated and lose load-bearing capacity — a pavement that can carry 18,000 kg on a tandem in January may be damaged at 14,000 kg in April.

Spring restriction dates and multipliers vary by province and by road class. Provincial highway authorities publish the start and end dates each year, typically in late February or March. Fines for overloading during spring restrictions are among the most severe in Canadian trucking law — Saskatchewan regularly issues fines exceeding $5,000 per incident.

Reading your result

• Active limit (kg): The maximum legal weight for your axle type in the current season. This is the number that determines compliance.
• Normal limit: The year-round base limit, before any spring reduction.
• Spring limit: The reduced limit during spring restriction season.
• All axle limits: The calculator also shows limits for all four axle types for your selected province, so you can verify the full truck configuration at once.
• Governing regulation: The specific provincial act and regulation number — the same authority a commercial vehicle inspector cites during a weigh station stop.

Limitations and important notes

• Weight limits shown are for provincial highways. Municipal roads, resource roads, and federal Crown roads may have different (often lower) limits. Always check posted signs — a posted limit overrides the provincial regulation for that specific road.
• This calculator returns axle group limits, not gross vehicle weight (GVW) limits. GVW limits are separate and are determined by the combination of axle limits and the Bridge Formula (which limits weight based on axle spacing). A truck can comply with each individual axle limit but still exceed the GVW limit.
• Oversize or overweight permits (OS/OW) can authorize weights above the standard limits. This calculator does not address OS/OW permits — contact your provincial highway authority for permit requirements.
• Regulations change. While we update the data table when provinces amend their regulations, always verify with the current provincial publication for compliance-critical decisions.