Sidereal & Solar Time Calculator
Calculate Greenwich and Local Sidereal Time based on mean solar time, date, and longitude.
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🌟 Why Sidereal Time? Sidereal time measures the rotation of Earth relative to the distant stars rather than the Sun. One sidereal day is exactly 23 hours, 56 minutes, and 4.09 seconds.
LST represents the Right Ascension coordinate that is currently directly overhead on the local celestial meridian. It matches Solar Time around the Autumnal Equinox (September 22).
Explore Additional Utilities
Current Speed Converter
Convert tidal, ocean, and river current speeds between knots, meters per second (m/s), and kilometers per hour (km/h).
Narcosis depth — nitrogen % ↔ equivalent air depth
Calculate Equivalent Narcotic Depth (END) and Equivalent Air Depth (EAD) for nitrox and trimix gas breathing mixtures.
Crop Yield & Land Estimator
Estimate field harvest yields and translate bulk units (bushels, tons) across distinct land measurement scales.
Bleed & Margin Helper
Convert print bleed and margins, and calculate print-ready canvas sizes for offset printing.
Optical density ↔ transmittance — filter blocking level
Convert between Optical Density (OD), transmittance fraction/percentage, and attenuation factors for safety glasses.
Cooking Unit Converter
Convert kitchen recipe volume structures: cups, milliliters, tablespoons, teaspoons, and fluid ounces.
Equatorial Coordinates Converter
Convert Right Ascension (RA) and Declination (Dec) to Hour Angle and Alt-Azimuth coordinates.
Displacement tonnage ↔ cubic meters — ship buoyancy
Convert ship displacement tonnage to submerged volume (m³) and buoyancy force. Choose between freshwater and saltwater standards.
Lumber Size & Board Feet Calculator
Calculate board feet volume, convert between nominal and actual lumber sizes, and estimate weights.
Weld throat thickness ↔ leg length — fillet weld geometry
Convert between throat thickness and leg length for fillet welds. Estimate joint volume, weld weight, and shear load capacity.
Knitting Gauge Converter
Convert knitting and crochet stitches and rows count between centimeters and inches.
Cooling load — room size ↔ BTU ↔ tons of refrigeration
Calculate room-by-room air conditioner cooling load requirements in BTU, tons, and kilowatts based on area, insulation, and occupants.
Yarn Weight Converter
Convert yarn sizes across WPI (Wraps Per Inch), ply, and standard weight categories.
Prism Power Converter
Convert ophthalmic prism power between prism diopters (PD) and degrees of deviation, with light bending estimations.
One Rep Max (1RM) Calculator
Estimate your single repetition maximum lifting capacity (1RM) using major clinical lifting models (Epley, Brzycki, Lander).
Roof Pitch Calculator
Convert between roof pitch ratios, degrees, and percentages, and calculate rafter lengths.
Pulp consistency — dry fiber % ↔ water ratio
Calculate dry fiber weight percentage in wet pulp slurry and water mixing dilution ratios for vat dipping.
Clinical Blood Pressure Gauges
Compare clinical medical blood pressure or vacuum values between mmHg and kPa units.
URL Slug Generator
Generate clean, hyphenated, SEO-friendly slugs from any string with custom separators.
Layer height ↔ print time estimator
Estimate 3D print duration changes and total layer counts when switching layer heights and print speeds.