Consumer did not recommend spray-on sunscreens because it was hard to get thick enough coverage from them.
"You also don't want children inhaling the spray."
They tended to be more expensive because part of the product was lost in the air.
Frederikson said Consumer recommended that people buy sunscreen that was at least SPF30, water-resistant and broad spectrum.
Paul Salmon, of the Skin Centre, said even the cheapest sunscreens would provide good protection against UVB, which causes burning.
"UVA protection depends as much on how much sunscreen you apply as what's in the product. People notoriously under-apply."
Dermatologist Louise Reiche said that because of the way people applied sunscreen, an SPF 50+ would provide the same protection in practice as SPF15+ in a lab test.
"If you're a teenager and you're pretty sloppy and don't put much on, SPF80 might be closer to what you need than SPF50. But if you're putting on a generous amount, you don't need to go to SPF80."
Countdown said most sunscreens sold were SPF30, but SPF50 was becoming more popular.
Reiche said some sunscreens lasted longer on the skin than others. She said the Cancer Society sunscreen had to be applied every two hours but Neutrogena Helioplex or DayLong, which can be bought only from pharmacies, could last up to eight hours.
She said it could be better value to buy a more expensive sunscreen that did not have to be applied as often as a cheaper product.
A day cream from top model Miranda Kerr's product range was criticised for its lack of sun protection, despite claims on packaging. Reiche said cosmetic products containing sunscreen could be problematic.
"I do not trust the SPF rating on moisturisers or cosmetics because I know they don't have to mean what they say. You're better to use a sunscreen that works with your skin and put makeup over the top. That would be the most economical anti-ageing thing you can do."
New Zealand has no mandatory standards for sunscreen, and they aren't expected until 2016, when the new Australia New Zealand Therapeutic Products Agency takes over.
Stephanie Evans, who produces Oasis sunscreen, said standards should now be mandatory.
"It's very strange that in a country where the UV rays are so dangerous there's no regulation for sunscreen."
She said her products were sent to Australia for testing, although this was not required.
"You could make sunscreen, guesstimate the SPF based on the ingredients and then sell it. I would welcome regulation because we're putting it on our kids and you can't have people guesstimating that."
