Interactive technician tools

DIAGNOSTIC CALCULATORS.

Convert electrical measurements without leaving the diagnostic workflow. Calculations run entirely in the browser and send no data anywhere.

MATH SUPPORTS THE TEST

A correct calculation cannot fix an invalid measurement. Confirm units, operating state, tool scaling and vehicle-specific limits first.

LOCAL & PRIVATE

Quick workshop math.

Choose a calculator, enter the measurements and calculate the result. Results are general calculations—not component specifications or repair authorization.

01 / CALCULATOR

OHM’S LAW

Enter exactly two values to calculate the third.

Enter the measurements above.

Inductive and electronically controlled loads may not reach the simple steady-state result.
02 / CALCULATOR

VOLTAGE-DROP PERCENTAGE

Convert a measured loaded drop into percentage of source voltage.

Enter the measurements above.

Measure while the circuit carries normal current.
03 / CALCULATOR

PARALLEL RESISTANCE / CAN TERMINATION

Calculate any number of parallel resistors.

Enter the measurements above.

A 60 Ω CAN expectation applies only to the correct powered-down topology with two 120 Ω terminations.
04 / CALCULATOR

PARASITIC-DRAW RUNTIME

Estimate idealized time before a selected percentage of battery capacity is consumed.

Enter the measurements above.

This estimate ignores temperature, aging, Peukert effects and required starting reserve.
05 / CALCULATOR

CURRENT-CLAMP SCALING

Convert a scope reading using a clamp’s millivolts-per-amp scale.

Enter the measurements above.

Confirm clamp direction, zero and the selected range before interpreting polarity.
06 / CALCULATOR

FREQUENCY ↔ PERIOD

Enter either frequency or period to calculate the other.

Enter the measurements above.

Use full-cycle period, not pulse width.
07 / CALCULATOR

DUTY CYCLE

Calculate duty cycle from high time and total period.

Enter the measurements above.

Some automotive tools report low-side duty or invert the displayed polarity.
08 / CALCULATOR

RESISTIVE CURRENT & POWER

Estimate steady-state current and power from applied voltage and resistance.

Enter the measurements above.

Coils, motors, lamps and electronic drivers are not purely resistive during every operating state.
09 / CALCULATOR

UNWANTED RESISTANCE & HEAT

Calculate connection resistance and heat from loaded current and measured voltage drop.

Enter the measurements above.

Small resistance can create substantial heat in high-current starter, fan, pump and heater circuits.
10 / CALCULATOR

CALCULATED VOLTAGE DROP

Estimate circuit drop from current and resistance.

Enter the values above and calculate.

Vdrop = I × R. Use this model alongside loaded measurements and the vehicle specification.
11 / CALCULATOR

HORSEPOWER & TORQUE

Convert torque and engine speed to horsepower, or calculate torque from horsepower.

Enter the values above and calculate.

Horsepower = torque in lb-ft × RPM ÷ 5252. Use values measured at the same operating point.
12 / CALCULATOR

ENGINE DISPLACEMENT

Calculate engine capacity from bore, stroke and cylinder count.

Enter the values above and calculate.

Displacement = π/4 × bore² × stroke × cylinders. Inputs are millimeters; results include cc, liters and cubic inches.
13 / CALCULATOR

COMPRESSION RATIO

Calculate the geometric compression ratio for one cylinder.

Enter the values above and calculate.

Ratio = (swept volume + clearance volume) ÷ clearance volume. Use the same volume units. This does not predict a compression-gauge reading.
14 / CALCULATOR

TIRE SIZE

Calculate nominal sidewall height, diameter, circumference and revolutions per mile.

Enter the values above and calculate.

These are nominal geometric dimensions. Loaded rolling circumference varies with tire construction, pressure and load.
15 / CALCULATOR

UNIT CONVERTER

Convert pressure, temperature, torque, length and power in either direction.

Enter the values above and calculate.

Select the direction before entering a value. Power conversion uses mechanical horsepower.