eGFR Kidney Function Calculator
Estimate glomerular filtration rate using the standard CKD-EPI (2021) equation with staging diagnostics.
Mildly Decreased GFR (clinical observation required if kidney damage present)
This calculator utilizes the 2021 CKD-EPI creatinine equation, recommended by the American Society of Nephrology (ASN) and the National Kidney Foundation (NKF). This updated formula removes race coefficients to provide equitable, unbiased diagnostic accuracy.
Explore Additional Utilities
Telescope resolution — aperture ↔ arcsecond limit
Determine telescope diffraction limits (Dawes' Limit/Rayleigh Criterion) and light gathering power.
Semitones & Pitch Intervals
Convert pitch ratios to semitones and cents, and calculate frequency intervals.
Preheat temperature — steel grade + thickness → °C
Estimate preheat temperatures using Carbon Equivalent (CE) chemistry formulas and plate thickness guidelines to prevent hydrogen cracking.
Angular Motor Rotation
Determine crankshaft engine RPM, radian ratios, and angular physical velocities.
Nail size — penny (d) ↔ mm ↔ inches length
Convert traditional penny (d) nail sizes to absolute physical lengths in millimeters and inches, including standard shank gauge and nail types.
Period Tracker & Predictor
Track menstrual cycles, predict future period start dates, cycle phases, and typical symptom occurrences.
ND Filter Stops Converter
Convert ND filter labels (ND density, optical density, and stop reduction) and calculate long exposure shutter speed compensation.
Shrinkage allowance — finished size ↔ cut size
Calculate required pattern cut sizes from finished garment specs or expected post-wash sizes.
Braille Translator (Grade 1)
Convert standard text into visual Grade 1 Braille cell dots, and design custom cells using an interactive 6-dot braille builder.
Draw weight — lbs ↔ kg — bow poundage
Convert between Pounds (lbs) and Kilograms (kg) draw weights. View recommended setups for various target types.
Fumigation concentration — space volume ↔ gas amount
Calculate target gas fumigant weight/volume based on structure cubic volume, target ppm concentration, and temperature.
Hardness converter — Rockwell ↔ Brinell ↔ Vickers
Convert between Rockwell C, Rockwell B, Brinell, and Vickers scales with approximate tensile strengths for steel materials.
NPK Fertilizer Blend Designer
Calculate exact commercial fertilizer weights (Nitrogen, Phosphate, Potash) required to hit crop nutrient targets.
Stone size ↔ carat estimator
Estimate carat weight of round, oval, emerald, pear, or marquise cut gemstones from their physical dimensions and specific gravity.
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.
Electron volts ↔ joules ↔ nanometers — photon energy
Convert between photon energy (eV, Joules) and physical wavelengths (nm, pm) or frequency (THz).
Bohr radius ↔ nanometers — atomic scale reference
Determine electron orbital radius and binding energy levels for Hydrogen-like atomic configurations.
Exposure time — emulsion type ↔ UV source ↔ seconds
Estimate photo-emulsion exposure durations for screen printing frames or solar plates using light distance calculations.
Propeller pitch ↔ boat speed — theoretical boat speed
Calculate theoretical boat speed and actual speed based on propeller pitch, engine RPM, gear ratio, and hull slip percentages.
Quench rate — steel grade ↔ medium — oil vs water vs air
Identify ideal quench mediums and tempering guidelines for hardening various carbon and alloy steel grades.