Luminance contrast and AS 1428.1: the 30% rule, the formula and how to prove it (NSW)
AS 1428.1 generally requires a minimum luminance contrast of 30% between key surfaces so people with low vision can find them. Most failures come from picking the wrong pair of surfaces or trusting a brochure LRV without calculation. Current NSW work is assessed against NCC 2022 Amendment 2 (which calls up AS 1428.1-2009) until NSW adopts NCC 2025 on 1 May 2027. Confirm clause numbers and wording in the Standard that applies to your project.
The short answer
30% minimum luminance contrast, calculated with the Bowman–Sapolinski formula, applies to doorways, stair nosing strips, frameless glazing lines and accessible toilet seats under AS 1428.1. Tactile ground surface indicators use 30%, 45% or 60% under AS/NZS 1428.4.1.
Where luminance contrast is required
Confirm the exact clauses in the edition called up by your NCC reference:
| Element | Typical requirement | Notes |
|---|---|---|
| Doorways | 30% between one of five surface pairs, contrast area at least 50 mm wide | One pair is enough. See accessible doors. |
| Stair nosing strips | 50–75 mm deep, set back no more than 15 mm, 30% to background | See nosings on stairways. |
| Frameless glazing line | Contrasting line, typically 75 mm high, lower edge 900–1000 mm, 30% against floor within 2 m | See visual indicators on glazed doors. |
| Accessible toilet seat | 30% contrast | See disabled toilet regulations. |
| TGSIs | 30% integrated, 45% discrete, 60% for contrasting element of composite discrete | See TGSI compliance audits. |
Handrails, switches and signage: state only what the called-up Standard requires. Do not assume 30% applies everywhere.
How luminance contrast is calculated
The Bowman–Sapolinski formula is:
C = 125 (Y2 − Y1) / (Y1 + Y2 + 25)
where Y2 is the lighter surface (LRV 0 to 100) and Y1 the darker. Worked examples (re-calculate before use):
- Y1 10 / Y2 30 → about 38.5% (passes)
- Y1 20 / Y2 40 → about 29.4% (fails, same 20-point gap)
- Y1 60 / Y2 80 → about 15.2% (fails, same 20-point gap)
A 20-point LRV difference is not a reliable rule of thumb. Calculate.
Doors: pick your pair early
Five permitted surface pairs; one is enough. Detail the 50 mm band. Common traps: timber leaf in timber frame, white frame on white wall. Link to the doors page for full detail.
Stairs and nosing strips
Strip depth, setback and contrast to the tread. Single colour. See related stair pages for handrails and open risers.
Glazing manifestations
The contrasting line rules and the viewed-against-the-floor test. Put the colour in the specification; the supplier should not choose it.
TGSIs
30% integrated, 45% discrete, 60% for the contrasting element of composite discrete under AS/NZS 1428.4.1. See the TGSI audit page.
Evidence: from finishes schedule to OC
At design stage (CC): record LRVs on the finishes schedule and door/stair details. During construction: check samples and substitutions. Before OC: on-site measurement may be needed, wet and dry for external or wet areas. A suitably equipped tester performs the measurement; NATA accreditation where the certifier or contract requires it. Sydney Access Consultants does not claim NATA accreditation.
See AS 1428.1:2009 vs 2021 for edition questions. Using the 2021 edition early can be a Performance Solution.
How Sydney Access Consultants helps
Finishes and drawings review, contrast pairs written into the access report, coordinating tests when needed. Call (02) 9586 3111. Work is based in Hurstville. On the Mid North Coast, Sandy Grey works from Black Beach.
Related: access audits, what certifiers want.
Frequently asked questions
What luminance contrast does AS 1428.1 require?
AS 1428.1 generally requires a minimum luminance contrast of 30% between key surfaces so people with low vision can find them. That covers a doorway (between the door leaf, jamb, architrave or adjacent wall, in a band at least 50 mm wide), the nosing strip on each stair tread, the contrasting line on frameless glazing, and an accessible toilet seat. Tactile ground surface indicators are covered by AS/NZS 1428.4.1 instead, which sets 30% for integrated, 45% for discrete and 60% for the contrasting part of composite discrete indicators.
Is 30% luminance contrast the same as a 30-point LRV difference?
No. Luminance contrast is calculated with the Bowman–Sapolinski formula: C = 125 (Y2 − Y1) / (Y1 + Y2 + 25), where Y2 is the lighter surface. A 20-point LRV gap can pass on dark surfaces and fail on light ones. Always calculate, do not subtract.