Bra Size Calculator Accuracy Checklist
Set up your space, capture precise measurements, and validate the fit so every calculator run delivers reliable bra recommendations.
1. Prepare your environment
A stable environment keeps measurements consistent. Run through this quick pre-check before picking up the tape.
- Choose a well-lit room with a full-length mirror and flat flooring.
- Wear a non-padded bra or measure braless to capture natural shape.
- Relax shoulders and keep breathing steady to avoid ribcage expansion.
- Use a flexible measuring tape (or ribbon + ruler) that can contour smoothly.
2. Measure with precision
Snug underbust
Wrap the tape directly under the bust, parallel to the floor. Exhale gently and pull until the tape is secure but not painful. Record to the nearest 0.5 cm or 0.25 in.
Fullest bust
Measure at nipple level while standing upright. Keep the tape parallel and avoid compressing the tissue. Note the same unit as the band measurement.
Confirm the unit setting
Match the calculator input (cm or in) to the units you recorded. Switching mid-way is the most common source of errors.
Enter numbers precisely
Type the decimals exactly as recorded. Avoid rounding until after the calculator presents its normalized band size.
3. Validate the fit
After trying your recommended size, complete these checks to confirm accuracy before removing tags.
Band mirror check
After trying the recommended size, ensure the band sits level around the torso and does not ride up when arms move overhead.
Cup containment
Look for smooth cup edges without gaping or overflow. Slight gaping can be solved with strap adjustment; major issues point to sister sizes.
Strap tension
Straps should stay in place without digging. If they carry too much weight, evaluate a tighter band sister size.
Breath & movement test
Take deep breaths, twist side-to-side, and perform light arm circles. The bra should remain stable while allowing free movement.
4. Keep the accuracy momentum
- Log measurements in the downloadable template so you can compare trends over time.
- Re-measure every 6 months or after major lifestyle changes (training shifts, hormone therapy, pregnancy).
- When testing sister sizes, adjust only one step at a time to isolate band vs cup effects.
- Save calculator results and international conversions as screenshots before shopping in another region.
Downloadable resources
Frequently asked questions
How precise do my measurements need to be?→
Record to the nearest 0.5 cm or 0.25 in. The calculator normalizes band size to the nearest even number, so accurate decimals refine cup volume calculations.
What if my underbust and bust vary day to day?→
Track measurements for a week and use the median. Hormonal changes can affect fullness—logging trends keeps results consistent.
Should I round the calculator result when shopping?→
Keep the exact size the calculator provides, then test adjacent sister sizes in-store if necessary. Rounding beforehand can lead to the wrong band tension.