Period underwear has grown in popularity in recent years, with a number of brands entering the market long dominated by specialist brands such as Modibodi, Love Luna and Thinx.
In March this year, Kmart became one of the latest brands to launch a period underwear range – releasing a bikini and full brief option for just $12 each.
To find out how how well they work, we recruited 16 volunteers to trial both pairs and assess them for comfort, absorbency, ease of use and more.
The gusset is made of four absorbent layers. Image: Kmart.
What are Kmart period briefs?
At a glance, both the bikini and full brief period briefs look just like an ordinary pair of Kmart underpants – the difference is you can wear these on your period either as standalone menstrual protection, or as backup when wearing a tampon or menstrual cup. This is because the gusset is made of four layers for "absorbency and protection" to wick away moisture and odour.
The briefs come in two styles – bikini (moderate absorbency) and full brief (heavy absorbency) – are made of 95% cotton and are available in sizes 6 to 20.
Do they work?
Sixteen CHOICE staff were recruited to try both pairs of Kmart period underwear – one for daytime (bikini brief, moderate absorbency) and one pair for overnight (full brief, heavy absorbency). For more information, see how we test.
Overall, triallists preferred the full brief more than the bikini brief, although both pairs were rated fairly evenly when it comes to comfort, fit, odour control and drying.
(Note: Triallists' comments have been edited for length and clarity.)
Kmart period full briefs
- Price: $12
- Absorbency: Heavy
- Worn by triallists overnight
- Claimed absorption: 3–4 tampons (mL not stated)
- Made in Indonesia
Kmart period full briefs, which three out of four triallists rated good, very good or excellent.
Generally the participants were positive about these briefs, with three in four rating them good, very good or excellent.
Most of the participants (10 out of 16) said they'd prefer to wear these undies alone, and two said they'd wear them with a tampon or menstrual cup.
Kmart's full briefs leakage rating is impressive – 15 out of 16 triallists reported no leaks whatsoever. But the one person who did report a leak described it as a large one: "The blood just sat on the surface of the underwear like it was waterproof!"
It also rated well for absorbency, with 13 rating it good or better. Of the 16 participants, nine rated odour control as good, very good or excellent.
For both comfort and fit, 13 out of 16 participants rated the briefs as good or better.
Ease of use
When asked about ease of washing, 10 rated it as good, very good or excellent. Ease of drying scored marginally higher, with 11 triallists rating it good or better.
Some triallists said they liked the "soft, cotton feel material" and that the "fabric was breathable and fit comfortable".
Others felt unsure about the absorbency: "It seemed thinner than other brands. This makes me doubt its ability to be used without leaking or additional protection on heavier days."
One triallist just wasn't a fan of the style: "These were proper granny undies! Super high-waisted and low-cut on the legs. Which is good for reassurance that you're not going to leak, but doesn't exactly make you feel attractive!"
Kmart period bikini briefs
- Price: $12
- Absorbency: Moderate
- Worn by triallists in the daytime
- Claimed absorption: 2–3 tampons (mL not stated)
- Made in Indonesia
Kmart period bikini briefs, which just under half (seven) of our triallists rated good, very good or excellent.
Just under half (seven) of the triallists rated the bikini briefs as good, very good or excellent.
Seven participants said they'd prefer to wear these undies alone and five said they'd wear them in addition to a tampon or menstrual cup.
Just over half (nine) of the triallists rated the absorbency as good or better and 75% reported no leaks while wearing the briefs.
Of the 16 participants, 10 rated odour control as good, very good or excellent.
The briefs were rated similarly for both comfort and fit, with 11 participants rating both as good, very good or excellent.
Ease of use
Ease of washing rated slightly higher than ease of drying, with about three-quarters of participants respectively rating it good or better.
Some triallists commented on these briefs as being a "great value product" and "comfy".
"I was worried it wouldn't be good quality given the cost, but was pleasantly surprised," said one triallist.
"Overall they were really comfy and worked well for me, so I will use them again," said another.
Not all good news
Others highlighted some negatives, such as it being difficult to tell when full and that the briefs probably wouldn't be good for heavier days.
One commenter said: "I just didn't think it was that much different to normal underwear. The gusset wasn't thick enough to do enough absorbing."
Another commented: "They're fairly thin in the gusset/absorbent area. I have quite a light flow so it wasn't a problem for me, but it might be a bit disconcerting if you have a heavy flow."
The bikini briefs before (above) and after our laundry lab test.
Laundry lab wear and tear
We sent a pair of both the bikini and full briefs to CHOICE's laundry laboratory to find out how well they last over time after multiple wash and dry cycles. (For details, see how we test.)
The bikini briefs started to fray at the hem almost straight away and both products demonstrated slight pilling by the end of the test. Both briefs also faded quite significantly.
That said, both briefs generally held up well and are still in good working condition.
Traillists were asked to wash and dry each pair according to instructions found on the packaging/undies before wearing.
The briefs were trialled on a moderate flow day during the triallists' cycle, with the day pair starting from when they got dressed for the day, changing into the overnight pair as they got ready for bed. On average, both pairs of undies were worn for 8.3 hours each.
The traillists also completed a post-trial survey form and were asked to rate each pair on a scale from terrible to excellent. Each pair of undies was trialled a minimum of 16 times in total.
Laundry lab wear and tear test
The undies were washed in a large, impeller top-loading washing machine on a cotton cold cycle, with half a scoop of detergent for each wash.
Based on the assumption you might bung them in the dryer instead of line-drying, for every five washes the undies were put through a gentle dryer program. For every 20 washes (and once more at the conclusion of the test), they were put through an intensive dryer cycle.
In total, the undies ran through 48 wash cycles and 10 dryer cycles (three of which would be considered intensive).