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Find constellations by RA/Dec coordinates, search all 88 IAU constellations by name, or list what's visible tonight from your location. Free, browser-based.

Convert between earthquake magnitude scales — Mw, Ms, ML (Richter), mb, and Md. Estimates seismic moment, energy in joules, and TNT equivalent. Free, browser-based.

Calculate wind chill (feels-like temperature) from air temperature and wind speed. Uses the official NWS / Environment Canada 2001 formula with frostbite risk guidance. Free, browser-based.

Calculate heat index (feels-like temperature) from air temperature and relative humidity. Uses the official NWS Rothfusz formula with heat risk guidance. Free, browser-based.

Calculate dew point from temperature and relative humidity, or find RH from temperature and dew point. Shows vapor pressure, absolute humidity, and comfort level. Free, browser-based.

Calculate air density from temperature, pressure, and humidity, or from altitude. Shows kg/m³, virtual temperature, speed of sound, and comparison to sea-level standard. Free, browser-based.

Convert between altitude and atmospheric pressure using the barometric formula or ISA standard atmosphere. Pressure in hPa, inHg, kPa, and more. Free, browser-based.

Calculate rock bulk density from mass and volume, rectangular blocks, or drill cores. Porosity from grain density. Compare to typical granite, basalt, limestone, and more. Free, browser-based.

Estimate your annual carbon footprint from car travel, flights, home electricity, and natural gas. Compare to global averages with regional grid factors. Free, browser-based.

Calculate rainfall volume from catchment area and depth, estimate storm runoff with a runoff coefficient, or compute rainfall intensity (mm/hr). Metric and imperial units. Free, instant, browser-based.

Calculate volumetric flow rate Q = A × v for pipes and open channels, estimate flow with Manning's equation, or convert between L/s, GPM, CFS, and m³/s. Metric and imperial units. Free, instant, browser-based.

Calculate river discharge Q from channel width, depth, and mean velocity (velocity–area method), trapezoidal cross-sections with bank slope, or Manning's equation. Results in m³/s, L/s, and CFS with river size classification. Free, browser-based.