Jeweler Calculator.

Carit is the jeweler calculator app for the US bench jeweler - ring sizes in quarter-size steps, 10k / 14k / 18k gold purity, platinum 950, sterling silver, pennyweight and troy ounce conversions, and pricing in USD. Used in workshops from New York to LA, Chicago to Tucson. Built by a bench jeweler. Available on iOS and Android.

Built for the US bench

The US jewelry trade has its own conventions. Ring sizes run 3 through 13 in quarter-size steps. Gold purity is quoted in karat (10k, 14k, 18k most common - 22k rare outside Indian and Middle Eastern pieces). Weights are often expressed in pennyweight (dwt) rather than grams at the wholesale level - 1 dwt = 1.555 g - and troy ounces at the bullion level (1 ozt = 31.1 g). Pricing is in US dollars pulled from COMEX spot.

Carit defaults to US conventions when you set the app locale to English (US): quarter-size ring sizes, karat abbreviation (K), pennyweight and troy ounce options in the metal weight module, USD pricing.

Every calculator inside Carit

This is the US jeweler's overview. Each calculator has its own documentation page - follow the links for the underlying math, reference tables and bench-tested examples.

US gold purity standards Carit supports

US karat stamping is less regulated than UK hallmarking but is still the universal language of US gold jewelry. Carit supports every common US karat and converts to parts-per-thousand when you need to match an international spec.

14k and 10k gold dominate the US market. Carit's alloy recipes default to US-standard master-alloy ratios for yellow, white and rose at each karat.

US ring size conventions

US ring sizes run from 3 (very small) through 13 (very large) and beyond, in quarter-size steps: 3, 3¼, 3½, 3¾, 4, and so on. Each quarter-size step equals approximately 0.2 mm of inner diameter. The most common US women's size is 6½ (17.0 mm inner diameter, 53.1 mm circumference). The most common US men's size is 10 (19.8 mm inner diameter, 62.3 mm circumference).

Carit's ring sizer handles all US quarter sizes plus conversion to UK letters, EU millimeters and Japanese whole-number codes. Full detail: ring size calculator →

Pennyweight and troy ounce support

US wholesale jewelry is often priced by the pennyweight (dwt). 1 pennyweight = 1.55517 grams, and 20 pennyweight = 1 troy ounce (31.1 grams). Carit's metal weight calculator outputs in all three units simultaneously, so you can quote a casting in grams for your CAD file and pennyweight for your grain supplier without doing manual conversion.

Live metal prices in USD

Carit pulls live gold, silver, platinum and palladium prices from market feeds and displays them in your chosen currency - USD is the default for US locale. Every casting weight and ring weight calculation multiplies through the current spot price, so quotes reflect today's market not last week's. Live pricing is a Carit Pro feature.

Who uses Carit in the US jewelry trade?

Carit is used by US bench jewelers across the country: New York jewelry-district setters and remount shops, Chicago Jewelers Row goldsmiths, Los Angeles custom studios, San Francisco Bay Area designer-makers, Tucson gemstone-show vendors, and independent bench jewelers from Portland to Miami. Also used in US jewelry programs at GIA, Revere Academy, the New Approach School, North Bennet Street School, and other leading training institutions.

If you're in the UK or internationally

If you prefer UK spelling and UK conventions (letter sizes, ct rather than K, fineness marks like 750), see the UK-spelling version: jewellers calculator (UK). Both pages document the same Carit app with regional context. The app itself supports 27 languages and all four ring-size systems.

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