Science calculators

How long a battery lasts from capacity in mAh or Wh, draw in mA or watts and an efficiency factor — plus the capacity a target runtime would need.

Estimate the heating and cooling BTUs a room needs from its size, insulation, sun exposure, climate zone and occupancy, with the tonnage and every adjustment shown.

Convert power or amplitude ratios to decibels and back, and add two dB sources, with the 10·log vs 20·log distinction spelled out.

Calculate density from mass and volume in any units, or solve for mass or volume — results in kg/m³, g/cm³ and lb/ft³ with a reference table of common materials.

C₁V₁ = C₂V₂ solved for stock volume, final concentration, stock concentration or final volume, with the solvent to add and the dilution factor.

Newton's second law solved for force, mass or acceleration, plus weight on any planet from NASA surface gravities — in newtons, pounds-force and kgf.

Fall time and impact speed from a drop height, or distance and speed after a given time, with optional initial velocity and gravity, plus a height-vs-time table.

Gear ratio from tooth counts, with output RPM, torque multiplication and mechanical advantage, and an optional second stage for compound gear trains.

Exponential decay solved for remaining quantity, half-life or elapsed time, with decay constant, mean lifetime, a decay curve and a table of isotope half-lives.

Horsepower from torque and RPM, from a quarter-mile time and weight with the Fox and Hale formulas, or from a 0–60 time, with kilowatts and power-to-weight.

Solve PV = nRT for pressure, volume, moles or temperature with any units (atm, kPa, psi, L, °C, K) using R = 8.314462618 J/(mol·K), with every step shown.

Calculate kinetic energy from mass and velocity (KE = ½mv²) in joules, kJ or kcal, plus momentum — or solve for the velocity or mass that gives a known energy.

Series resistor for an LED or LED string: required ohms, the nearest E12 part, the current you actually get, power dissipated and the wattage to buy.

Molarity from moles or from grams and molar mass, or the mass of solute you need to make a target concentration — volumes in mL, L or gallons, with the work shown.

Type a chemical formula, brackets and hydrates included, and get the molar mass, each element's contribution and the percentage composition, from IUPAC weights.

Momentum p = mv from mass and velocity in any units, plus 1-D elastic and perfectly inelastic collisions with final velocities and kinetic energy lost.

The Moon's phase, age and illuminated fraction for any date, plus the next new and full moons — computed with Meeus's periodic series, accurate to about a minute.

Solve V = IR and P = VI for voltage, current, resistance or power from two known values, with the rearranged formula shown and all 12 Ohm's-law equations.

pH from [H⁺], [H⁺] from pH, pH from pOH, or the pH of a strong acid or base from its concentration — with [OH⁻], the log steps and a temperature-aware Kw.

Power from work and time (P = W/t), force and speed (P = Fv) or voltage and current (P = VI) in watts, kW, horsepower and BTU/h, with energy use per hour and day.

Range, maximum height, time of flight and impact velocity for a projectile at any speed, angle and launch height, with a plotted trajectory and the equations shown.

Decode 4, 5 and 6-band resistor colour codes to resistance, tolerance, min/max value and temperature coefficient, using the IEC 60062 colour table.

Q = mcΔT solved for heat, mass, specific heat or final temperature, with a sourced table of specific heats (water 4186, copper 385 J/kg·K) and J, kcal or kWh output.

Solve speed = distance ÷ time for any of the three, with hours-minutes-seconds input, km/h, mph or m/s output, running pace per km and per mile, and the steps shown.

Sunrise, sunset, solar noon, day length and civil twilight for any latitude, longitude and date, from the NOAA solar position algorithm. Polar day and night handled.

Torque from force and radius, force from torque, or power from torque and RPM — in N·m, lb·ft, watts and horsepower, with the 5252 constant explained.

Output voltage of a two-resistor divider (Vout = Vin·R2/(R1+R2)), the current and power in each resistor, and how a load resistance pulls the output down.

Convert between wavelength, frequency and photon energy (λ = v/f, E = hf) with exact CODATA constants, auto-scaled units from km to pm, and the spectrum band named.

Minimum AWG for a run from current, one-way distance, voltage and allowable drop, with the actual voltage drop, conductor resistance and a full AWG table.