One size,every system
Convert shoe, ring, clothing and pet sizes across US, UK, EU, JP and more — live, accurate, and honest about where brands differ. Free forever, no account needed.
Popular converters
The most-searched conversions, each with a live tool and a full reference chart.
Shoe Size Converter
US, UK, EU, JP, cm — men's, women's and kids'.
Open converter →Men's US 6.5 to UK
US 6.5 converts to UK 5.5 (men's).
View chart →Men's US 6.5 to EU
US 6.5 converts to EU 37 (men's).
View chart →Men's UK 5.5 to US
UK 5.5 converts to US 6.5 (men's).
View chart → Live toolRing Size Converter
US, UK, EU/ISO, JP, plus mm circumference & diameter.
Open converter →US 3 to UK
US 3 converts to UK F.
View chart →US 3 to EU
US 3 converts to EU 44.
View chart → Live toolClothing Size Converter
Women's & men's US, UK, EU with body measurements.
Open converter →Women's US 0 to UK Clothing Size
US 0 converts to UK 4 (women's).
View chart →Women's US 0 to EU Clothing Size
US 0 converts to EU 32 (women's).
View chart → Live toolDog Collar & Harness Calculator
Size by neck or chest, with the two-finger safety rule.
Open calculator →Chihuahua Collar Size
Collar XS · harness XS (neck 20–28 cm).
View guide →Yorkshire Terrier Collar Size
Collar XS · harness XS (neck 20–28 cm).
View guide → Live toolBed & Mattress Converter
UK ↔ US ↔ EU by real dimensions — a King isn't one size.
Open converter →UK Single to US Bed Size
90×190 cm → closest US is Twin (96.5×190.5 cm).
View →UK Single to EU Bed Size
90×190 cm → closest EU is Single (90×200 cm).
View → Live toolBike Size Calculator
Frame size from height or inseam — road, hybrid & MTB.
Open calculator →Bike for 154 cm (5'1")
Road 48 cm · hybrid 47 cm · MTB 16 in.
View →Bike for 161 cm (5'3")
Road 52 cm · hybrid 51 cm · MTB 17 in.
View →