Toilet training underwear is Stage 3 of toilet training. It's the step after training pants, once your toddler is mostly dry during the day and ready for something that looks, feels, and acts like real underwear. Think of it as the bridge between the "still might have an accident" stage and full-blown regular undies, the bit that gets your child mentally ready to think of themselves as a kid who wears proper underwear.
If your toddler has spent a few weeks in training pants and accidents are now down to one a day or fewer, this is the stage you're shopping for. This guide walks through exactly what's inside the pair, how the sizing actually runs, and how to choose with confidence.
What makes Rudie Baby training underwear different
Stage 3 underwear has one main job: feel like a real pair of undies, not a fallback. Ours are built off a Bonds boys trunk block in 95% bamboo viscose with 5% spandex. That fabric is the whole point. Bamboo viscose is silky-soft against toddler skin, breathable in the Aussie heat, and the stretch from the spandex means they hug without digging in. Most parents tell us their toddler refuses to take them off once they have them on, which is exactly the reaction you want at this stage.
The slim leakproof gusset is hidden inside the lining, not bulked up between the legs, so they sit flat under leggings, jeans, dresses, and a school uniform. From the outside, they look and feel like regular kids' undies.
"He didn't even know he had something different on. He just thought they were his regular undies, which was honestly the whole battle won." Renee, Brisbane
The 4-layer leakproof gusset, explained
The gusset is the four-layered absorbent core that sits between the legs. Each layer does a specific job:
- Outer layer (95% bamboo viscose, 5% spandex): Matches the body of the undie so it doesn't look or feel different from the rest of the garment.
- Waterproof layer (100% cotton with PU backing): The reason a small accident stays inside the gusset and doesn't end up on the couch or in the car seat.
- Absorbent layer (French terry, 80% cotton, 20% polyester): This is the thirsty bit. French terry has a looped pile that holds liquid well without going soggy on the surface.
- Skin-side layer (100% cotton jersey): Soft against the skin, and dyed to match the print background so you don't see a white panel through the leg openings.
The combination handles a typical small accident, the kind that happens between "I need to go" and actually reaching the toilet. It's not a swap for a nappy at night, and it's not designed for a fully wet. Think of it as forgiveness built into a real pair of undies.
How the sizing actually runs (ages 2 to 6)
Our toilet training underwear comes in three sizes, all unisex:
- Size 2/3: fits most toddlers aged 2 to 3
- Size 3/4: fits most kids aged 3 to 4
- Size 4/6: fits most kids aged 4 to 6
The shape is modelled on Bonds boys trunks, so the fit is familiar. Here are the actual flat measurements from the tech pack if you'd rather measure than guess:
| Measurement | Size 2/3 | Size 3/4 | Size 4/6 |
|---|---|---|---|
| Waist (flat, half) | 22 cm | 23 cm | 24.5 cm |
| Leg opening (flat, half) | 14 cm | 15 cm | 16.5 cm |
| Front body height | 16.5 cm | 17.5 cm | 20.5 cm |
| Total side body height | 13.5 cm | 14.5 cm | 15.5 cm |
| Knitted waistband height | 2 cm | 2 cm | 2 cm |
If your toddler is between sizes, go up. A snug waistband on a training undie isn't more secure, it just feels tight. The knitted waistband sits flat at 2 cm and won't roll, no matter which size you pick.
Whales or Unicorns? Choosing the print
We currently make our toilet training underwear in two unisex prints:
- Whales: soft blue base with white whales. The cleanest of the two if you're after a less busy look.
- Unicorns: pastel pink and lilac with unicorns scattered across the print. A bit bolder, popular with toddlers who pick their own outfits.
Both prints use the same construction, the same gusset, the same sizing. The choice comes down to what your toddler is going to be excited to put on. That sounds small, but it matters. A pair of undies they actually want to wear is a pair they'll tell you about before an accident, not after.
If you can't pick one, our 6-pack lets you mix prints (3 Whales plus 3 Unicorns is the most-ordered combo).
How to wash them (and make them last)
The care label is heat-transferred onto the inside back panel, so there's no scratchy tag for your toddler to fight with. The full care instructions:
- Machine wash at 40°C
- Wash similar colours together
- Tumble dry on low (or line dry)
- Do not bleach
- Do not iron
A few practical tips that aren't on the care label:
- Rinse a wet pair under cold water before it goes in the wash basket. It stops the urine from setting into the absorbent layer.
- Skip the fabric softener. It coats the French terry inner and reduces how much liquid the gusset can hold.
- If you're going through more than one accident a day in the early weeks, a 6-pack is much less stressful than a 3-pack. You're never down to your last clean pair.
"We just bought the 6-pack to start. Best call we made. Two on the line, two in the wash, two ready in the drawer." Mel, Adelaide
Looked after this way, our training undies hold up for the full training period, typically 3 to 6 months of daily wear, and most parents pass them down to a younger sibling after.
When training underwear is right (and when it isn't)
Training underwear is Stage 3. Your toddler should already be through the training pants phase before you introduce them. Specifically, they're ready when:
- They've spent a few weeks in training pants and accidents have dropped to one a day or fewer.
- They can pull undies up and down themselves.
- They're going to the toilet on purpose most of the time.
- You want them feeling like a kid in "real" underwear, not still wearing something that looks like a step before.
If your toddler is still having multiple full accidents a day, they're not at Stage 3 yet. The thin gusset isn't built for that volume, and the wet feeling on their skin without enough absorbency will frustrate everyone. Keep going with training pants for a bit longer and come back to these once things settle.
Nights are a separate question. Training underwear isn't built for overnight use. Stick with whatever overnight protection you're already using, and bring the undies in once daytime is solid.
How to buy
Our toilet training underwear is $24.95 per pair, or $99.95 for a 6-pack. Stock is held in Australia and ships from Melbourne. If you order before 1pm on a weekday, it's usually on your doorstep within 2 to 4 business days.
Still not sure on size or print? Send us an email and we'll usually reply within a few hours during business days.
