Gem & Jewelry Laboratory
Standardized carat measurements, karat alloy gold purity calculations, Troy ounce precious metal valuations, and historic UK assay hallmark decoding.
1. Assay Office & Hallmark Search
A complete UK hallmark consists of a sponsor mark, a fineness mark, the assay office mark, and historically a date letter representing the exact calendar year of assay testing.
2. Decoded Hallmark Information
Explore Additional Utilities
Fumigation concentration — space volume ↔ gas amount
Calculate target gas fumigant weight/volume based on structure cubic volume, target ppm concentration, and temperature.
Base64 ↔ hex ↔ binary — encoding format converter
Convert raw text strings or bytes bidirectionally between Base64, Hexadecimal, Binary, and standard ASCII formats.
Cable run — signal type + length → gauge required
Compute copper loop line resistance, voltage drop, and power loss to recommend the optimal wire gauge size (AWG).
Ohm's Law Calculator
Calculate voltage, current, resistance, and power using Ohm's Law and Joules Law formulas.
CFM ↔ m³/hour — air flow for ventilation
Convert ventilation air flow rates and reference standard design volumes for common room types and equipment hoods.
Engine power ↔ hull speed — planing vs displacement
Estimate maximum displacement hull speeds (LWL formula) or calculate planing hull speeds using Crouch's classic marine formula.
Original gravity ↔ potential ABV — beer brewing
Calculate alcohol by volume (ABV), attenuation percentages, and calorie estimations from Original and Final Gravity values.
Batch recipe ↔ percentage recipe — glaze chemistry
Normalize raw ingredient batch weights to percentage formulations or scale a recipe to any total batch weight.
Bread Dough Hydration Calculator
Convert between flour weight, water weight, and hydration percentages for perfect baking doughs.
Stride length ↔ cadence ↔ running speed
Analyze running biomechanics: calculate speed based on cadence (SPM) and stride length.
Beaufort Wind Force Scale
Convert wind speed units and classify storm conditions on the official Beaufort maritime wind power scale.
Drilling rate — ROP in m/hr ↔ ft/hr
Translate Rate of Penetration (ROP) and calculate specific drilling time, drilling speed efficiency, and shift performance.
Tree diameter ↔ basal area — forestry measurement
Convert tree breast height diameters to single tree basal area or estimate stand basal area densities per acre or hectare.
Nautical Distance & Speed Sizer
Convert distances between nautical miles, statute miles, and kilometers, and calculate knot-based speeds.
Numerical aperture ↔ acceptance angle — fiber coupling
Determine light coupling capabilities, supported modes, V-numbers, and acceptance cone widths for optical optical fibers.
Industrial & Tire Pressure Gauges
Convert heavy industrial or automotive pressure indicators across PSI, bar, kPa, and atm indexes.
Angular Scales & Rotations
Convert degrees, radians, and gradians for geometric or angular rotations.
Navy Body Fat Estimator
Estimate body fat percentage using standard US Navy circumference measurements.
ND Filter Stops Converter
Convert ND filter labels (ND density, optical density, and stop reduction) and calculate long exposure shutter speed compensation.
Batting average ↔ on base percentage — baseball stats
Convert batting average, walks, and plate appearances into On-Base Percentage (OBP).