CSA Score Estimator

A BASIC percentile is a weighted violation rate compared with a peer group. This models that shape with the published weights so you can see the size of the move a single violation makes — before the truck leaves the yard rather than after.

One BASIC, before and after

This models the shape of the calculation, not FMCSA's exact percentile. It shows how much one more violation moves you, which is the question worth asking before the trip.

added: 0
Weighted violations, before
50
Weighted violations, after
50
Rate per inspection, after
4.17

Indicative percentile now

99

Above intervention

After the added violations

99

Above intervention

Low-poly render of an empty weigh-station apron
An empty apron. What happens on it stays on the record for two years.

What it checks — and what it is not

It multiplies your violations by the published time weights, multiplies by an average severity, divides by your relevant inspection count, and compares that rate against a peer figure you supply. That is the shape of the Safety Measurement System calculation.

It is not FMCSA's percentile. The real calculation uses per-violation severity values, a utilisation factor, and a peer group derived from the whole population. Read the direction and the size of the move here, then read your actual number on the agency's own site.

Worked example

Twelve relevant inspections in two years, six violations spread across the three time bands, average severity five. Press "add a violation today" once and the weighted total jumps by fifteen — a fresh violation counts three times, and the severity multiplies it again.

Now raise the inspection count to thirty and press it again. The same violation barely moves the needle. That is the peer-group effect: exposure is the denominator, and a small carrier with few inspections is structurally more volatile than a large one.

Where the weights come from

The time weights — three, two and one, dropping out at twenty-four months — and the one-to-ten severity range are published in FMCSA's Safety Measurement System methodology. The methodology is revised from time to time, so check the current document before treating any of these numbers as permanent; the link is below.

Sources

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