Bra Size Calculator in CM — Metric Band & Cup Sizes | BraSizeHelper

Why Use Centimeters for Bra Sizing?

Centimeter-based measurement is standard in much of Europe and in everyday life for anyone who uses the metric system. Measuring your underbust and bust in centimeters can reduce confusion when brands publish size charts in cm, and some people find metric readings easier to read on a standard sewing or body tape. As with any sizing method, the number you calculate is a starting estimate — final fit still depends on brand, style, and how the bra is constructed.

Our metric calculator converts your cm readings into US, UK, and other regional labels so you can shop internationally without manually cross-referencing multiple charts. If you are more comfortable thinking in inches, you can switch to our bra size calculator in inches instead; both tools draw from the same underlying logic with unit-appropriate rounding.

Tools and Preparation

Use a soft measuring tape that shows centimeters clearly. Stand in front of a mirror with good lighting, arms relaxed. Wear a non-padded bra or measure on bare skin — padded cups can add volume that skews bust readings. Breathe normally throughout; holding your breath can artificially tighten the band measurement.

• Underbust (band): Place the tape directly beneath the breast tissue, parallel to the floor.
• Bust: Measure around the fullest part of the chest, keeping the tape level front and back.
• Record accurately: Note readings to the nearest centimeter; our calculator accepts typical whole-cm inputs.

Measuring Band Size in CM

Wrap the tape snugly under your bust. It should feel secure enough to stay in place when you move your arms, but not painfully tight. Read the centimeter value where the tape meets itself. Many sizing systems relate this underbust cm figure to a labeled band size through conversion tables — for US sizes, the band number is not identical to your raw cm reading, which surprises some first-time measurers.

Because brands differ in how much elastic they build into a band, you might wear a 75 cm-underbust person in a 34, 75, or 80 band depending on the label’s country and stretch. Treat conversion output as guidance and confirm by how the hook closure feels on the loosest hook when the bra is new.

Checking Band Level and Posture

Ensure the tape does not dip in back or ride up in front. Turn sideways in the mirror to verify. Small posture adjustments change cm readings slightly; consistency matters more than chasing a perfect single number.

Measuring Bust Size in CM

At the fullest point of your bust, wrap the tape around your body. The tape should skim the skin without pressing breast tissue flat. If you have softer tissue, a very loose tape may overestimate bust cm; a overly tight tape underestimates. Aim for a middle ground similar to how fabric lightly contacts skin in a well-fitted bra.

For asymmetrical breasts, some guides suggest measuring both sides or using the larger side as reference. Fitting with removable pads or stretch lace can help balance minor asymmetry that raw numbers do not capture.

From CM Readings to Cup Size

Cup volume is typically estimated from the difference between bust cm and underbust cm, mapped to letter grades. Metric cup steps are not always one cm per letter across every international system — UK and US letter progressions diverge at larger cups — but our calculator applies widely used conversion paths so you see a coherent US or UK label alongside metric context.

Enter both measurements on this page’s calculator widget, choose centimeters, and review the suggested size. Sister sizes — same cup volume, different band — appear to help you bracket fit if the first result feels too loose or snug.

Compare With Our Main Calculator

The main bra size calculator lets you toggle between inches and cm in one place, which is useful if you measured with one tape but want to see results in both unit systems. For first-time measurers, our how to measure bra size walkthrough covers technique in detail, including what to do if you land between cm marks on the tape.

Shopping With Metric Measurements

EU lingerie often lists band sizes in centimeters (70, 75, 80, etc.) while US tags show 32, 34, 36. Knowing your cm measurements helps you scan brand charts quickly, especially on European retailer sites. Still compare against each brand’s chart — “75” does not always mean the same fit across every designer.

When buying sports or minimizer bras, cup depth and wire width may differ even when the metric math matches a previous purchase. Trying two adjacent sizes remains one of the most reliable ways to validate a cm-based calculation.

Re-Measure and Track Changes

Life changes affect cm measurements as much as inch ones. Re-measure if you notice cups gapping, wires sitting on breast tissue, or shoulder straps doing all the support work. Tracking underbust and bust cm in a note every few months can reveal gradual shifts before your bras become obviously uncomfortable.

Brand Variance Disclaimer

Centimeter calculations provide educated size estimates, not certainties. Manufacturing tolerance, fabric recovery after washing, and personal fit preference all play roles. BraSizeHelper aims to simplify metric measurement math; your comfort in a specific bra model is the final test. Consult brand size charts and consider professional fitting for complex shapes or medical breast changes.