Featured contributor PhD Applied Physics; former research associate at a national metrology lab.

Dr. Helena Ortiz

Senior Reviewer, Science & Engineering

0 calculators 0 articles Member since Jun 2026

About

Helena is the senior technical reviewer for physics, chemistry, and unit-conversion calculators. She is the last pair of eyes on every formula — checking constants, units, and edge cases against primary sources and standards bodies.

She holds a PhD in Applied Physics and previously held a research post at a national metrology lab.

Areas of expertise

Physics Chemistry Unit conversion Measurement standards

Education & credentials

BSc Physics — Universidad Complutense de Madrid
PhD Applied Physics — Stanford University

Finance

Customer Acquisition Cost (CAC) Calculator

Calculates CAC = total marketing & sales spend / number of new customers acquired. Also computes LTV:CAC ratio if lifeti...

basic

1,588 4.2 1 min

Chemistry

Ksp Solubility Product Ion Concentration Calculator

Calculates the molar solubility and ion concentrations of a sparingly soluble salt from its Ksp and stoichiometry (e.g.,...

basic

24,277 4.6 1 min

Chemistry / Solutions

Mass Fraction to Molality Conversion Calculator

Convert the mass fraction of a solute w (g solute / g solution) to molality b = w / (M_solute × (1 − w)), with M in kg/m...

basic

22,851 3.9 1 min

Chemistry

Molar Absorptivity (Extinction Coefficient) from Absorbance Calculator

Calculates molar absorptivity ε = A/(c·l) and solute concentration c = A/(ε·l) from absorbance A, path length l, and eit...

basic

24,644 4.8 1 min

Physics / Electricity

Electric Potential from a Point Charge Calculator

Compute the electric potential V (volts) at distance r from a point charge q, taking V = 0 at infinity: V = k · q / r, w...

basic

929 4.0 1 min

Chemistry / Reactions

Gas Molar Mass from Density Calculator

Compute the molar mass of an ideal gas from its density, the temperature, and the pressure, using M = ρRT / P (R = 0.082...

basic

18,696 4.5 1 min

Health

Simplified SOFA Score (Organ Failure) Calculator

Calculates a simplified SOFA score from six organ system parameters to assess severity of illness and predict ICU mortal...

basic

2,994 3.9 1 min

Chemistry

Lattice Energy via Born-Haber Cycle Calculator

Estimate the lattice energy of an MX-type ionic solid by closing the Born-Haber cycle: U = ΔH_f − ΔH_sub − ½·BE(X-X) − I...

basic

16,849 4.8 1 min

Physics / Electricity

Ideal Transformer Current Balance Calculator

Compute the secondary (load) current of an ideal transformer from the primary current and the turns ratio, and verify po...

basic

23,405 4.3 1 min

Health

Gestational Weight Gain (IOM Guidelines) Calculator

Recommends total gestational weight gain ranges based on pre-pregnancy BMI according to the Institute of Medicine (IOM)...

basic

23,202 4.5 1 min

Physics / Mechanics

Spherical Wave Intensity (Inverse-Square) Calculator

Compute the wave-power intensity at distance r from an isotropic point source emitting total power P: I = P / (4π · r²)....

basic

4,872 4.7 1 min

Physics / Mechanics

Distance Modulus Calculator

Compute the distance modulus and luminosity distance to an astronomical object from its apparent and absolute magnitudes...

basic

24,489 3.8 1 min

Showing 25 to 36 of 504 results

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Reviewed by Dr. Helena Ortiz

These calculators were technically reviewed by Dr. Helena Ortiz for accuracy.

Chemistry / Reactions

Equilibrium Constant Calculator

Compute the equilibrium constant K_c from the concentrations of two products (with stoichiometric coefficients 1) divide...

basic

5,060 4.0 1 min

Conversions / Length

Length Converter

Convert between meters, kilometers, miles, feet, inches, and yards.

Featured basic

4,964 4.2 1 min

Chemistry / Solutions

Combined Gas Law Calculator

Find the missing pressure, volume, or temperature using the combined gas law for a fixed amount of gas.

basic

5,360 4.2 1 min

Physics / Electricity

Capacitance Calculator

Compute the capacitance of a parallel-plate capacitor from plate area, plate separation, and the dielectric constant.

basic

12,524 4.1 1 min

Chemistry / Solutions

pOH Calculator

Compute pOH from hydroxide ion concentration and the matching pH at 25 °C.

basic

18,221 4.2 1 min

Ecology / Carbon Footprint

Carbon Footprint Calculator

Estimate your annual personal CO₂e footprint from home energy, driving, flying, and diet — with adjustable emission fact...

Featured basic

15,825 4.9 1 min

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Browse categories

Dr. Helena Ortiz

Customer Acquisition Cost (CAC) Calculator

Ksp Solubility Product Ion Concentration Calculator

Mass Fraction to Molality Conversion Calculator

Molar Absorptivity (Extinction Coefficient) from Absorbance Calculator

Electric Potential from a Point Charge Calculator

Gas Molar Mass from Density Calculator

Simplified SOFA Score (Organ Failure) Calculator

Lattice Energy via Born-Haber Cycle Calculator

Ideal Transformer Current Balance Calculator

Gestational Weight Gain (IOM Guidelines) Calculator

Spherical Wave Intensity (Inverse-Square) Calculator

Distance Modulus Calculator

Reviewed by Dr. Helena Ortiz

Equilibrium Constant Calculator

Length Converter

Combined Gas Law Calculator

Capacitance Calculator

pOH Calculator

Carbon Footprint Calculator