Ovulation & Fertility Calculator
Calculate your ovulation day, high-fertility windows, and probability of conception.
Fertility Inputs
Thursday, Jul 9, 2026
Calculated based on your last period date and a luteal phase length of 14 days. Real ovulation timing can shift based on stress, sleep, or hormones.
Day-by-Day Fertile Window & Conception Probabilities
Gender Conception Theory (The Shettles Method)
The Shettles method proposes that male sperm (Y-chromosome) are faster but more fragile, while female sperm (X-chromosome) are slower but more resilient.
Intercourse should take place 2 to 4 days before ovulation. fragiler Y sperm die off, leaving resilient X sperm when egg is released.
Intercourse should take place as close to ovulation as possible. Swift Y sperm are more likely to reach the egg first.
*Disclaimer: The Shettles method is an educational theory with scientific debate. True chance is approximately 50/50 for any conception event.
Explore Additional Utilities
Spring rate — lb/in ↔ N/mm — suspension setup
Convert suspension coil spring stiffness between lb/in and N/mm. Estimate coil spring rates using wire diameter, coil diameter, and active counts.
Refractive index ↔ critical angle — fiber optic design
Determine the boundary reflection critical angles and Fresnel reflection losses for Total Internal Reflection.
Fuel burn rate — engine HP ↔ liters per hour
Calculate marine engine fuel consumption (liters/hr or gal/hr) using Brake Specific Fuel Consumption (BSFC) or standard marine power constants.
Crop Yield & Land Estimator
Estimate field harvest yields and translate bulk units (bushels, tons) across distinct land measurement scales.
JSON Formatter
Format, validate, beautify, and minify your JSON data structures in real-time.
Watch beat rate — BPH ↔ Hz ↔ vibrations per hour
Convert mechanical watch balance wheel frequencies between Beats Per Hour (BPH), Vibrations Per Hour, and Hertz (Hz).
Enthalpy ↔ temperature ↔ pressure — steam tables
Estimate saturated water and steam properties including boiling point, saturated pressure, and enthalpies.
Drilling rate — ROP in m/hr ↔ ft/hr
Translate Rate of Penetration (ROP) and calculate specific drilling time, drilling speed efficiency, and shift performance.
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.
Ore dilution — grade ↔ waste ↔ recovered grade
Calculate recovered ore grade, tonnage adjustments, dilution percentages, and mining waste contamination levels.
Mortar mix ratio — cement ↔ sand ↔ water by weight
Calculate standard masonry mortar mix classes (Type M, S, N, O, K) and determine precise cement, sand, and water weights.
Block count — wall area ↔ number of blocks needed
Calculate standard concrete masonry units (CMU) or clay bricks required for a wall, adjusting for joint widths and waste factors.
Essential oil dilution — drops ↔ % in carrier oil
Convert dilution percentages to drop counts and precise weights for facial, body, and therapeutic carrier oils.
Chlorophyll concentration ↔ water color index
Convert Chlorophyll-a bio-concentrations (mg/m³) to ocean water color classes, Forel-Ule index, and trophic status.
Dew point ↔ condensation risk — wall insulation check
Check wall surface dew point parameters and assess condensation and mold growth risks from room relative humidity.
Scientific Temperature Scale
Convert scientific scales between Celsius, Fahrenheit, Kelvin, and Rankine thermal indicators.
Clinical Blood Pressure Gauges
Compare clinical medical blood pressure or vacuum values between mmHg and kPa units.
Reading & Speaking Timer
Convert total word counts to estimated reading or speaking time at standard speeds.
Viscosity — cosmetic grade cps ↔ product texture description
Map centipoise (cPs) values to tangible product textures and view standard cosmetic grade shear behaviours.
Base Number Converter
Convert raw numbers seamlessly between Binary, Octal, Decimal, and Hexadecimal formats with active bit layouts.