Some prediction quiz questions can feel unrelated to the product you're selling — seat shape on a t-shirt quiz, or bra size on a skirt quiz. That's on purpose: the quiz isn't measuring your product, it's understanding the shopper's body. Every answer feeds one complete body picture, and that complete picture is what makes the size recommendation accurate.
This only applies to the prediction quiz: its machine-learning model has to predict the shopper's key measurements — bust, waist, and hips — to build the overall composition of the body.
Same height, same weight, same age — different bodies
Imagine two shoppers. Both are 170 cm tall and weigh 70 kg. One carries more volume around the belly; the other carries it around the hips. They need different t-shirt sizes — but height and weight alone can't tell them apart.
That's what the body-shape questions are for. Asking where the weight sits — belly, hips, chest, seat — is the only way to turn "170 cm, 70 kg" into a real body shape.
Every answer sharpens the whole picture
The prediction model doesn't estimate one measurement at a time — it estimates chest, waist, and hips together, from the shopper's height, weight, age, and shape answers. Weight sits on the body as a whole, so a question that looks unrelated still improves the measurements your product does need:
On a t-shirt quiz, the seat-shape answer helps the model place the shopper's waist and chest more accurately.
On a skirt quiz, the bra-size answer tells the model how weight is distributed on the upper body — which sharpens the waist and hip estimate.
Once the full body picture is ready, the recommendation only compares the measurements your product's size chart actually uses — chest and waist for a top, waist and hips for bottoms. The shopper answers a handful of simple questions; the model does the rest.
For example, we may ask for your customer's bust size even if they are shopping for skirts.
Only the prediction quiz works this way
The precision quiz has none of these questions. There, the shopper enters their measurements directly, so there is nothing to predict — the quiz only asks for the measurements it will actually compare against your size chart.
The body-shape questions exist only in the prediction quiz, where the model must estimate bust, waist, and hips from whole-body answers. For a full comparison of the two, see The difference between a precision quiz and a prediction quiz.
Bonus: one quiz, instant sizes everywhere
Because the quiz builds a complete body picture — not just the parts one product needs — it works for your whole catalog. A shopper who takes the quiz on a pair of jeans and then opens a jacket page gets their jacket size instantly, without answering anything again. Their answers are remembered for about 3 months (see How is fit quiz usage calculated?).
If the quiz only asked product-specific questions, shoppers would have to start over on every product page.
💡 The short answer for your shoppers: every question helps us understand your overall body shape, so we can recommend the right size for this product — and for anything else you browse, instantly.