Pregnancy Bra Size Calculator
Track your changing bra size throughout pregnancy. Get personalized sizing recommendations for each trimester based on typical breast and ribcage changes.
Calculate Your Pregnancy Bra Size
Pregnancy Bra Size Guide by Trimester
First Trimester
Weeks 1-12
- • Breast tenderness and sensitivity
- • Cup may increase 1 size
- • Band usually stays same
- • Consider soft, wire-free bras
Second Trimester
Weeks 13-27
- • Ribcage begins expanding
- • Band may increase 1-2 inches
- • Cup continues to grow
- • Look for extender hooks
Third Trimester
Weeks 28-40+
- • Maximum ribcage expansion
- • Band may be +2-4 inches
- • Cup may be +2-3 sizes
- • Consider nursing bras
What to Look for in a Pregnancy Bra
Wide, Comfortable Straps
Distribute weight evenly and reduce shoulder strain
Multiple Hook Positions
Allows for ribcage expansion throughout pregnancy
Soft, Breathable Fabric
Cotton or bamboo blends for comfort and temperature regulation
No Underwire (Early Pregnancy)
Wire-free reduces pressure on sensitive breast tissue
Stretchy Cup Material
Accommodates fluctuating breast size throughout the day
Seamless Construction
Minimizes irritation on sensitive skin
Frequently Asked Questions
When should I start wearing a maternity bra?
Most women switch to a maternity or soft bra by the end of the first trimester when breast tenderness peaks and regular bras become uncomfortable. However, some may need one earlier or later depending on their body.
How many pregnancy bras do I need?
We recommend 2-3 well-fitting bras at a time. Since your size will change, buy only what you need for your current stage rather than stocking up. Many women transition directly to nursing bras in the third trimester.
Will my pre-pregnancy bra size return after birth?
It varies - some women return to their pre-pregnancy size within a few months of finishing breastfeeding, while others experience permanent changes. Your ribcage may remain slightly larger, and breast tissue may change in volume and distribution.
Related Tools
Our content is researched, written, and regularly updated by our editorial team using the A Bra That Fits (ABTF) methodology — the same approach validated by the 500,000+ member r/ABraThatFits community. We cite peer-reviewed research, lingerie industry standards, and community data. Our calculators process data locally in your browser; we do not collect body measurements.
We use the modern 6-measurement ABTF method rather than the outdated +4 inch rule. This approach has been independently validated by the r/ABraThatFits community to produce more accurate and comfortable bra sizes than traditional two-measurement methods.