Chemistry & Physics
Chemistry & physics tools are free online calculators that solve equations for energy, pressure, density, concentration, decay and voltage — for students, teachers, lab techs and engineers.
Free combined gas law calculator solves P1V1/T1 = P2V2/T2 for any variable. Enter five values to find pressure, volume or temperature, with worked examples and a unit chart.
Free density calculator solves ρ = m/V for density, mass or volume. Enter any two values to find the third, with worked examples and a density chart.
Free electricity cost calculator turns watts, hours and price per kWh into daily, monthly and yearly running costs, with worked examples and an appliance chart.
Free half life calculator finds the remaining amount after radioactive decay using remaining = initial × (1/2)^(t / half-life), with worked examples and a decay chart.
Free kinetic energy calculator solves KE = ½mv² for energy, mass or velocity. Enter two values to get joules, kilograms or m/s, with worked examples and a chart.
Free molarity calculator: enter any two of moles, litres and molarity to solve for the third. Includes the molarity formula (M = moles ÷ litres) and worked examples.
Free ohms law calculator solves V = I × R and power P. Enter any two of volts, amps, ohms or watts to find the rest, with worked examples and a chart.
Free pH calculator: enter pH, pOH, [H+] or [OH-] and instantly get all four values plus acidic, neutral or basic. Includes the pH formula and worked examples.
Free projectile motion calculator finds range, max height and time of flight from launch speed, angle and height. No air resistance, with worked examples and a chart.
What are chemistry & physics tools?
Chemistry & physics tools are free online calculators that solve scientific equations and rearrange them for any unknown. They cover acidity and pH, gas behaviour, kinetic energy, density, solution concentration, radioactive decay, electrical circuits, projectile trajectories and energy cost. Students, teachers, lab technicians and engineers use them for fast, checkable answers in the correct SI units without working the algebra by hand.
Chemistry & Physics tools on Toolzent
Here are the chemistry & physics calculators currently available, each with worked examples on its page:
| Tool | What it does |
|---|---|
| pH Calculator | Enter pH, pOH, [H+] or [OH-] and get all four values plus an acidic, neutral or basic label at 25 degrees C. |
| Combined Gas Law Calculator | Solves P1V1/T1 = P2V2/T2 for any variable from five known values, with temperature in Kelvin. |
| Kinetic Energy Calculator | Solves KE = half m v squared for energy, mass or velocity in joules, kilograms and m/s. |
| Density Calculator | Solves density = mass / volume for density, mass or volume using any consistent units. |
| Ohm’s Law Calculator | Enter any two of volts, amps, ohms or watts to find the rest using V = I times R and power P. |
| Projectile Motion Calculator | Finds range, maximum height and time of flight from launch speed, angle and height, ignoring air resistance. |
| Molarity Calculator | Solves M = moles / litres for molarity, moles or volume, the standard measure of solution concentration. |
| Half-Life Calculator | Solves radioactive decay for remaining amount, elapsed time or half-life using the exponential decay law. |
| Electricity Cost Calculator | Estimates running cost from device wattage, hours of use and your price per kilowatt-hour. |
Core formulas and units at a glance
These are the equations behind the calculators above, with the units each tool expects. Keep them nearby when checking your own working.
| Quantity | Formula | Units |
|---|---|---|
| pH | pH = minus log10[H+] | concentration in mol/L; pH unitless |
| Combined gas law | P1V1/T1 = P2V2/T2 | matching P and V units; T in Kelvin |
| Kinetic energy | KE = half m v squared | J, kg, m/s |
| Density | density = mass / volume | e.g. kg/m3 or g/cm3 |
| Molarity | M = moles / litres | mol, L, mol/L |
| Half-life | N = N0 times (half) to the power t/T | same amount unit; matching time unit |
| Ohm’s law | V = I times R; P = V times I | V, A, ohms, W |
| Energy cost | cost = kW times hours times price | kW, hours, price per kWh |
A few worked results, exactly as the tools return them: a hydrogen ion concentration of 1 times 10 to the minus 3 mol/L gives pH 3.00 (acidic). A 2 kg object moving at 10 m/s has KE = 0.5 times 2 times 100 = 100 joules. Dissolving 0.5 mol of solute in 2 L of solution gives a molarity of 0.25 mol/L. With V = 12 V and I = 2 A, the Ohm’s law tool returns R = 6 ohms and P = 24 watts.
How do I choose the right tool?
Match the tool to the quantity you need to find:
- Working with acids, bases or hydrogen ion concentration? Use the pH Calculator to convert between pH, pOH, [H+] and [OH-].
- Preparing or diluting a solution? Use the Molarity Calculator to find concentration, moles or volume.
- Predicting how a gas changes between two states? Use the Combined Gas Law Calculator, and convert any temperature to Kelvin first.
- Tracking radioactive or exponential decay? Use the Half-Life Calculator for remaining amount, time or half-life.
- Finding energy of motion, or a required mass or speed? Use the Kinetic Energy Calculator.
- Identifying a material or converting between mass and volume? Use the Density Calculator with consistent units.
- Sizing a resistor or checking current and power in a DC circuit? Use the Ohm’s Law Calculator.
- Solving a trajectory for range, height or flight time? Use the Projectile Motion Calculator.
- Estimating what an appliance costs to run? Use the Electricity Cost Calculator.
If you only know two values, that is enough for most of these tools, since each one rearranges its formula to solve for whatever is left.
Why use Toolzent’s chemistry & physics tools?
Every calculator is 100% free with no sign-up and nothing to install. The tools run privately in your browser, so the values you enter stay on your device and results appear instantly. Each page is mobile-friendly and documents the underlying formula plus worked examples, so you can both get an answer and verify it. They assume ideal conditions where stated (for example, no air resistance in projectile motion and 25 degrees C for pH), so treat results as clean textbook values rather than measured lab data.
Explore more free calculators in related hubs such as Math & Algebra, Unit Converters and Statistics & Probability.
Frequently asked questions
Are these chemistry & physics tools free to use?+
Yes. Every chemistry and physics calculator on Toolzent is 100% free, with no sign-up, no download and no usage limits.
Why must temperature be in Kelvin for the gas law calculator?+
Kelvin starts at absolute zero, so the ratios in P1V1/T1 = P2V2/T2 stay meaningful; Celsius breaks the ratio and can divide by zero at 0 degrees C. Add 273.15 to convert.
How do I calculate molarity?+
Molarity is moles of solute divided by litres of solution (M = mol / L). Convert grams to moles with the molar mass first, then divide by the volume in litres.
What does half-life mean and how is it used?+
Half-life is the time for a quantity to decay to half its starting amount; the Half-Life Calculator finds remaining amount, elapsed time or the half-life itself from the decay equation.
Does doubling an object's speed double its kinetic energy?+
No. Because velocity is squared in KE = half m v squared, doubling speed multiplies kinetic energy by four, and tripling speed multiplies it by nine.
Are the calculations private and accurate?+
Yes. Calculations run locally in your browser, results are computed in full precision and rounded for display, and each tool states its formula so nothing is uploaded or hidden.