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Use Fit Lab to tune recommendations

Guide type: Task guide Difficulty: Advanced Applies to: Fit quizzes

Test how a fit quiz recommends sizes for different body types without leaving the editor.

How do I make my quiz recommend the right size?

Fit Lab lets you preview how your quiz responds to different body measurements before shoppers see it. Adjust your size table, fit settings, and measurement priorities in the quiz editor, then test common body shapes to verify the recommendations make sense.

Before you start

  • The quiz has a completed size table.
  • The quiz has product fit settings configured. If you have not set the product type, fit ease, or measurement priorities, follow Product fit, stretch, and measurement priorities first.
  • You understand what sizes the quiz should recommend for common body shapes.

1. Open Fit Lab

In SmartSize, go to Fit quizzes and open the quiz you want to test. Scroll to Advanced settings and expand Fit Lab Simulator.

2. Enter a test shopper profile

Type a height, weight, and any other measurements the quiz collects. For a Prediction quiz, start with height and weight. For a Precision quiz, enter the exact body measurements.

SmartSize Fit Lab Simulator recommending size S

Click Simulate. SmartSize shows the recommended size and explains why that size was chosen.

3. Read the simulation result

The result card tells you: - The recommended size. - Whether the fit is tight, regular, or loose based on the fit ease setting. - Which measurements fit well and which are near the edge of the range.

If the shopper is between sizes, the result explains which measurement priority broke the tie.

SmartSize Fit Lab Simulator showing a between-sizes result

4. Adjust settings and compare

If a recommendation feels wrong, change the product fit settings and run the same profile again.

For example, if a shopper with a 68 cm waist is getting size M but you believe they should get size S because the fabric stretches, open Product fit, raise Fabric stretch to Full, and click Simulate again.

SmartSize Fit Lab Simulator after modifying fabric stretch

Compare the two results. The change in stretch level should shift the recommendation for shoppers near size boundaries.

5. Test edge cases

Run simulations for body types that are likely to cause problems:

  • A shopper at the very top of one size range.
  • A shopper at the very bottom of the next size range.
  • A shopper with one measurement much larger than the others, such as a narrow waist and wide hips.
  • A shopper outside the size table range entirely.

Watch for nonsensical results, such as a size recommended when every measurement is out of range. If that happens, check that the size table min and max values are correct and that measurement priorities are ordered logically.

6. Verify the quiz is ready

Open the Verify quiz results checklist in Advanced settings.

SmartSize verify quiz results checklist

Confirm that: - Product fit is configured. - The size table is complete. - Fit Lab tests return sensible results. - The quiz is linked to products through product display rules.

If every check passes, the quiz is ready to publish.

7. Save the quiz

Click Save to store any changes you made during tuning.

Check the result

Make sure the quiz is set to Active so shoppers can see it on the storefront.

Fit Lab returns a clear size for common body types and a reasonable between-sizes result for edge cases. The recommendation explanations match the product design and fabric behavior you expect.