Find Your Bra Size in 2 Minutes, in Every Sizing System
Free calculators for every body and life stage, converters across 7 systems, and fixes for every fit problem. Every calculation runs in your browser; nothing you enter is ever stored.
7 sizing systems25+ country calculatorsBands 28-60, cups AA-PZero data stored
Which calculator do you need?
Start with the measured calculator if you have any tape or string. The rest fine-tune from there.
Start here
Bra Size Calculator
Two measurements, your size in all 7 systems plus sisters. The place to start.
AI Smart Fit (no tape)
No tape measure? Four questions produce a working range and a direction.
By life stage
Teen Calculator
Gentle, private, first-fitting friendly.
Senior Calculator
Comfort-first sizing for changing tissue.
Plus-Size Calculator
Bands to 60, cups to P, lean-forward method.
By purpose
Shopping from a specific country?
25+ region pages preset the calculator to local sizing and explain the label quirks.
The 4-step fit journey
1. Find your baseline
Two measurements into the calculator: your starting size in every system.
2. Check the fit
Run the 10 physical checks: band level, gore tacking, tissue inside wires.
3. Sister-size adjust
Band problems with fitting cups move one step along the sister ladder.
4. Fine-tune by shape and brand
Match styles to your shape and translate your size per brand.
Common fit problems, one-line fixes
Band rides up
Band down a size, cup letter up.
Full guide
Cups overflow
One cup letter up at the same band.
Full guide
Cups gape
Letter down, or a demi cut for your shape.
Full guide
Straps dig
Fix the band; straps only steady.
Full guide
Something else misbehaving? The problem solver covers all nine symptoms.
The knowledge hub
How to Measure
Two steps, with diagram, cm and inches.
Sister Sizes Explained
The cup-volume math behind the ladder.
The 10 Fit Checks
Printable, two minutes, settles any size.
Styles by Shape
All 8 shapes matched to cuts.
Pregnancy Sizing
Trimester by trimester to weaning.
DD+ Specialist Guide
Construction that carries G-K.
Common questions
How do I find my bra size?
Measure your snug underbust and your bust at the fullest point, then enter both in the calculator. The underbust sets your band and the difference sets your cup letter, shown across all 7 international systems.
Is this bra calculator free?
Completely: every calculator, converter and guide, with no account, email or payment. The site earns from clearly disclosed affiliate links in product guides, never from your data.
Does this site store my measurements?
No. Every calculation runs in your browser on your device; measurements are never transmitted, stored or logged. Closing the tab erases everything except a unit preference saved locally.
Do you add 4 inches to the underbust?
No. We use the modern no-add method: your band is your actual underbust rounded to sizing convention. The plus-four method predates stretch fabrics and produces loose, unsupportive bands today.
What are sister sizes?
Sizes sharing the same cup volume on different bands: one band down pairs with one letter up. 32DD, 34D and 36C form one family, which is how you fix band problems without losing cup fit.
Which sizing system should I use?
The one your shopping market uses: US and UK share bands but split cup letters after DD, Europe counts in centimeters, France adds 15, Australia uses dress numbers, Japan and Korea run cup-first labels. The converter maps any to all.
Why does my size differ between brands?
Brands cut to different fit blocks: cup depth, band stretch and wire width vary under identical labels. Your measurement is constant; the garments differ, which the brand decoder translates per brand.
How often should I remeasure?
Yearly as a baseline, plus after weight change, pregnancy, new medication or whenever a formerly good size starts failing fit checks. Teens: every 3 to 4 months while sizes move.
What size am I if I am between sizes?
Take the firmer band and the roomier cup as starting points, then let the 10 fit checks decide. Between-band wearers usually do best sizing the band down and the letter up.
Is there a bra size chart on this site?
Two: a complete printable chart covering bands 28-60 across all 7 systems, and an interactive version where tapping any size highlights its sister diagonal.