Engineering & science calculators that show their working
Free engineering & science calculators with full step-by-step solutions. Every calculator gives you the answer first, then the full step-by-step working underneath — the same steps you would hand in with homework or show on a job sheet.
Electrical calculators
Voltage Drop Calculator
How many volts a wire run loses, for single-phase, three-phase and DC, with the NEC wire table built in.
Ohm's Law Calculator
Any two of V, I, R and P give you the other two. The starter calculator for all electrical work.
Watts to Amps Calculator
Watts into amps for DC, single-phase and three-phase, with power factor where it applies.
Amps to Watts Calculator
Amps into watts for DC, single-phase and three-phase, with power factor where it applies.
Voltage Divider Calculator
The output voltage from two series resistors — sensor scaling, level shifting and biasing.
Resistor Color Code Calculator
Decode 4, 5 and 6 band resistors: value, tolerance and temperature coefficient, drawn as you pick.
Chemistry & statistics calculators
Molarity Calculator
Concentration from mass, moles and volume — or work backwards to a recipe that hits a target molarity.
Dilution Calculator
M1V1 = M2V2 with any one value solved for — the everyday stock-solution dilution tool.
Molar Mass Calculator
Molar mass from any formula — Ca(OH)2, Al2(SO4)3 and hydrates like CuSO4·5H2O included.
pH Calculator
pH from [H+], from pOH, or from a strong acid or base concentration — placed on the 0–14 scale.
Mean, Median & Mode Calculator
All three averages from one list, plus sum, count and range — with the sorted data shown.
Weighted Average Calculator
Grades weighted by credit, scores weighted by importance — each value counts in proportion to its weight.
How these calculators are checked
Every formula on this site has a public test set: hand-worked cases with the expected answers, including the awkward edges (three-phase vs single-phase, aluminum wire, five-band resistors, formulas with brackets). The test set is re-run against the live code before any change ships. See the test set.
CalcForge is for teaching and planning. Engineering results must be checked against the code and standards that apply where you work before anything is built or bought.