US to Brazil Ring Size

Convert US/Canada sizes to Brazilian ring numbers (aros) — essential when gifting or buying rings for Brazilian jewelers (Vivara, HStern).

Need to convert in reverse? Go to Brazil to US Ring Size Converter (Aro to US) →

Bilingual reference: Para a versão em português desta página, acesse Conversor de Tamanho de Anel EUA Brasil (EUA para Aro) →

Common US to Brazilian Aro equivalents

Standard US adult sizes correspond to Brazilian aro numbers 13 through 24. Use the calculator below for exact diameter matching.

US 5½ corresponds to Aro 14 (16.1 mm)
US 6¼ corresponds to Aro 16 (16.8 mm)
US 7¼ corresponds to Aro 18 (17.7 mm)
US 8 corresponds to Aro 20 (18.2 mm)
US 9 corresponds to Aro 22 (19.0 mm)
US 10 corresponds to Aro 24 (19.8 mm)

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US to Brazilian Aro conversion chart

Complete reference table from US size 3 through 14 mapped to Brazilian Aro standards, inside diameter, and circumference in millimeters.

US to Brazil ring size conversion chart
US / Canada SizeUS, CA	Brazil (Aro)BR	Inside Diameter (mm)	Inside Circumference (mm)
US / Canada SizeUS, CA3	Brazil (Aro)BR7	Inside Diameter (mm)14.0-14.1	Inside Circumference (mm)44.0-44.2
US / Canada SizeUS, CA3¼	Brazil (Aro)BR8	Inside Diameter (mm)14.5	Inside Circumference (mm)45.55
US / Canada SizeUS, CA3½	Brazil (Aro)BR9	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA4	Brazil (Aro)BR10	Inside Diameter (mm)14.8-15.0	Inside Circumference (mm)46.5-46.8
US / Canada SizeUS, CA4½	Brazil (Aro)BR11	Inside Diameter (mm)15.6	Inside Circumference (mm)49
US / Canada SizeUS, CA4¾	Brazil (Aro)BR12	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA5	Brazil (Aro)BR13	Inside Diameter (mm)15.6-15.7	Inside Circumference (mm)48.5-49.3
US / Canada SizeUS, CA5½	Brazil (Aro)BR14	Inside Diameter (mm)16.0-16.2	Inside Circumference (mm)50.5-51.9
US / Canada SizeUS, CA6	Brazil (Aro)BR15	Inside Diameter (mm)16.4-16.6	Inside Circumference (mm)51.5-51.9
US / Canada SizeUS, CA6¼	Brazil (Aro)BR16	Inside Diameter (mm)16.8-16.9	Inside Circumference (mm)52.5-53.08
US / Canada SizeUS, CA6¾	Brazil (Aro)BR17	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA7¼	Brazil (Aro)BR18	Inside Diameter (mm)17.7-17.8	Inside Circumference (mm)55.0-55.6
US / Canada SizeUS, CA7½	Brazil (Aro)BR19	Inside Diameter (mm)18.0-18.1	Inside Circumference (mm)55.5-56.6
US / Canada SizeUS, CA8	Brazil (Aro)BR20	Inside Diameter (mm)18.1-18.2	Inside Circumference (mm)57.0-58.12
US / Canada SizeUS, CA8½	Brazil (Aro)BR21	Inside Diameter (mm)18.5	Inside Circumference (mm)58.0-59.1
US / Canada SizeUS, CA8¾	Brazil (Aro)BR22	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA9¼	Brazil (Aro)BR23	Inside Diameter (mm)19.4	Inside Circumference (mm)60.0-60.94
US / Canada SizeUS, CA9½	Brazil (Aro)BR24	Inside Diameter (mm)19.5-19.7	Inside Circumference (mm)61.0-62.1
US / Canada SizeUS, CA10	Brazil (Aro)BR25	Inside Diameter (mm)19.7-19.8	Inside Circumference (mm)62.0-63.45
US / Canada SizeUS, CA10½	Brazil (Aro)BR26	Inside Diameter (mm)20.3-20.7	Inside Circumference (mm)63.5-64.6
US / Canada SizeUS, CA10¾	Brazil (Aro)BR27	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA11¼	Brazil (Aro)BR28	Inside Diameter (mm)21	Inside Circumference (mm)—
US / Canada SizeUS, CA11¾	Brazil (Aro)BR29	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA12	Brazil (Aro)BR30	Inside Diameter (mm)21.4-21.6	Inside Circumference (mm)67.5-68.49
US / Canada SizeUS, CA12½	Brazil (Aro)BR31	Inside Diameter (mm)21.8-22.0	Inside Circumference (mm)68.5-69.76
US / Canada SizeUS, CA13	Brazil (Aro)BR32	Inside Diameter (mm)22.2-22.3	Inside Circumference (mm)69.76-70.0
US / Canada SizeUS, CA13¼	Brazil (Aro)BR33	Inside Diameter (mm)22.6	Inside Circumference (mm)—
US / Canada SizeUS, CA13½	Brazil (Aro)BR34	Inside Diameter (mm)22.9	Inside Circumference (mm)—
US / Canada SizeUS, CA13¾	Brazil (Aro)BR35	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA14¾	Brazil (Aro)BR36	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA15	Brazil (Aro)BR37	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA15½	Brazil (Aro)BR38	Inside Diameter (mm)—	Inside Circumference (mm)—
US / Canada SizeUS, CA16	Brazil (Aro)BR39	Inside Diameter (mm)—	Inside Circumference (mm)—

Understanding Brazilian Aro vs. US sizes

Why US ring size numbers and Brazilian aros differ.

Brazilian jewelers (following ABNT NBR 16058 standards) use an integer "Aro" scale typically ranging from 7 to 35 for adults. US jewelers use a numeric scale from 3 to 13.5 with quarter and half-size fractions.

Because both scales are defined by precise inner diameter increments, converting between them requires matching the exact millimeter dimensions. If you are shopping from a US retailer for delivery to Brazil, or purchasing an imported ring, checking the diameter in millimeters guarantees the most accurate fit.