MTO Contrast Compliance Checker
HTA s.103(1) requires the owner name to be clearly visible on both sides. USDOT markings require sharp contrast under 49 CFR 390.21. Neither sets a numeric contrast ratio. We use the WCAG 2.1 relative luminance algorithm to compare your colour combination before you order.
🔬 MTO Contrast Compliance Checker
HTA s.103 requires clearly visible owner names; USDOT markings require sharp contrast under 49 CFR 390.21. WCAG 2.1 math is a design aid, not a vehicle-marking compliance test.
Optimal — visible at highway speed
WCAG 2.1 minimum: 4.5:1 • Highway visibility recommended: 7.0:1
Based on W3C WCAG 2.1 relative luminance algorithm adapted for vehicle signage. Not legal advice — verify with your compliance officer.
How It Works
The Math
For each colour, we calculate its relative luminance using the sRGB colour space formula from WCAG 2.1. The contrast ratio is then:(L1 + 0.05) / (L2 + 0.05)where L1 is the lighter colour. A ratio of 1:1 means identical colours; 21:1 is the maximum (black on white).
What the Thresholds Mean
| Ratio | Verdict | Meaning |
|---|---|---|
| 7.0:1 + | Optimal | Visible at highway speed, any weather. Exceeds all standards. |
| 4.5:1 – 6.9:1 | Pass | Meets minimum contrast. Consider adding a contrasting outline for visibility. |
| Below 4.5:1 | Fail | MTO officer may deem non-conforming. We block this combination to protect you. |
Why This Matters
Every year, thousands of Ontario carriers receive fines at weigh stations for non-conforming door lettering. The most common issue? Choosing a vinyl colour that looks fine in a garage but is unreadable at 100 km/h on the 401. Our compliance checker eliminates that risk entirely — if the math says fail, we will not print it.
⚠️ Legal Note: HTA s.103(1) requires clearly visible owner names. USDOT markings require sharp contrast and legibility from 50 feet in daylight while stationary. The 4.5:1 ratio is a WCAG design aid, not a legal vehicle-marking threshold. When in doubt, use white lettering on a dark vehicle or black lettering on a light vehicle.