Underwear & Lingerie
Bra Size Calculator
Find your true starting cup and band size using dual-measurement ribcage analysis. Includes sister-size alternatives and US, UK, and European conversions.
Empirical Sizing & Wellness
Accurate Sizing Tools Designed for Real Bodies.
Say goodbye to size chart guesswork, ill-fitting bras, pinching shoes, and restless mornings. HerSizeHub combines mathematical precision with evidence-based wellness guidance to help you navigate international sizing with confidence.
Interactive Sizing & Wellness Calculators
Select a tool below to calculate your customized size, conversion matrix, or physiological schedule.
Fine Jewelry
Ring Size Calculator
Convert inside ring diameter or finger circumference into verified US, UK, European (ISO), and Japanese jewelry sizes with knuckle compensation tips.
Footwear & Lasts
Women's Shoe Size Chart
Accurately convert your foot length in inches or centimeters to US, UK, and EU women's shoe sizes with width adjustments (Narrow to Extra-Wide).
Hormonal Wellness
Period & Cycle Calculator
Track upcoming period start dates, estimated ovulation windows, and cycle phases using evidence-based gynecological modeling across 3 future cycles.
Rest & Recovery
Circadian Sleep Calculator
Plan your bedtime or morning alarm around natural 90-minute ultradian sleep cycles to eliminate grogginess and wake up at the peak of REM sleep.
Editorial Standards
Why Mathematical Precision Matters
Traditional retail advice is cluttered with outdated formulas designed for rigid, non-stretch fabrics of the 1960s. We build our tools around contemporary anatomical research and verified international manufacturing standards:
Zero Guesswork Sizing
Every tool translates raw millimeter and inch tape measurements directly into verified cup, last, and circumference progressions without artificial inflation.
Multi-Market Conversions
Customized algorithms accommodate US, UK, Canadian, Australian, and European regional standards so you can shop international brands seamlessly.
Evidence-Based Wellness
Our cycle and circadian calculators strictly reflect peer-reviewed medical consensus (ACOG, Sleep Foundation), pairing estimates with transparent disclaimers.
Featured Fitting & Wellness Guides
Deep dives authored to help you understand your fit, body comfort, and sleep architecture.
The Sister Size Equation: How Bra Band & Cup Math Really Works
Why a 34C and a 36B hold the exact same cup volume, and how to use sister sizing to fix band slipping or underwire digging.
Women's International Shoe Size Conversion: US, UK & EU Lasts
Understand the mathematical difference between Paris Points and barleycorn increments when ordering shoes overseas.
How Hormonal Shifts Across Your Menstrual Cycle Impact Sleep
Clinical insights into why progesterone peaks disrupt REM sleep during the luteal phase, and evidence-based tips to optimize rest.
Frequently Asked Questions
Clear answers regarding sizing accuracy, privacy, and measurement science.
Why are sizing standards so inconsistent across brands?
Unlike scientific measurement standards, clothing, footwear, and lingerie manufacturers build their products on proprietary fitting models or dress forms called "lasts". Differences in fabric stretch, grade rules, and regional vanity sizing mean you can easily wear three different sizes across three separate brands. Our tools provide an empirical baseline based on raw anatomical measurements.
How do HerSizeHub calculators differ from generic sizing charts?
HerSizeHub calculators do not rely on outdated sizing rules (such as adding arbitrary 4 inches to underbust measurements). We utilize modern snug-fit calculations, cross-referenced international standards (ISO, SATRA, ACOG), and sister-sizing algorithms to give you actionable, customized sizing recommendations.
Are my measurements or wellness inputs saved on your servers?
No. All calculations are executed locally within your web browser using client-side JavaScript. HerSizeHub does not store your personal bust measurements, foot dimensions, or menstrual cycle dates on our servers.