Slip, slop, slap is drilled into Australians as a motto to live by but testing shows four in five sunscreens are failing to provide protection, prompting the Cancer Council to vow to send its products to the lab again.

Consumer advocacy group Choice tested 20 sunscreens with SPF 50 or 50+ labels and found only four met the criteria.

"Consumers expect sunscreen to protect them in line with the SPF rating on the product, but as our testing has shown, the SPF label doesn't always match what's in the bottle," Choice CEO Ashley de Silva said.

Some of the Cancer Council's sunscreen products were egregiously falling behind.

The Kids Clear Zinc 50+ tested at 33, the Everyday Value Sunscreen 50 scored 27 and the Ultra Sunscreen 50+ came in at just 24.

Only one product from the council matched the label - the Kid Sunscreen 50+, which scored a strong 52.

However, the council said it was complying with all the SPF ratings tagged on its bottles.

"Noting the test results published by Choice and out of an abundance of caution, we have submitted the four referenced products for further testing by an independent international laboratory," the council said.

Three other products from well-known brands - La Roche-Posay, Neutrogena and Mecca Cosmetica - delivered on their dermatological declarations.

Ultra Violette's Lean Screen SPF 50+ Mattifying Zinc Skinscreen scored the lowest, the consumer group said, returning an SPF of four.

Ultra Violette disputed Choice's testing methodology and results, saying it followed Therapeutic Goods Administration guidelines and did not arbitrarily slap on a SPF 50+ label.

"We do not accept these results as even remotely accurate," the company told AAP.

"Lean Screen contains 22.75 per cent zinc oxide, a level at which, when applied sufficiently, would render a testing result of SPF four scientifically impossible."

Industry body Consumer Healthcare Products Australia assured people they could step out into the sun "with full confidence in the quality, safety and effectiveness of Australian sunscreens".

The body said in a statement it worked closely with the Therapeutic Goods Administration and Standards Australia to ensure consumers were protected by some of "the most stringent requirements in the world".

Choice said it had informed the brands concerned, the goods administration and the Australian Competition and Consumer Commission of the results.

Mr de Silva tempered any concerns for people heading to beaches or enjoying scorching sunny days, noting that "any sunscreen is better than none at all".