Workshop calculators
Quick calculations that help a diagnosis: is the MAF right, which injector leaks, is the cable thick enough. Free, no sign-in, work on a phone in the workshop.
Fuel trim analysis
Enter short- and long-term fuel trims at idle and at 2,500 rpm and see whether the pattern points to a vacuum leak, the MAF sensor or the fuel supply.
Open calculator →Volumetric efficiency (MAF check)
Compare the MAF reading with the airflow the engine should draw at full throttle. Low volumetric efficiency points to a restriction, a cam timing fault or a MAF that under-reads.
Open calculator →Compression test
Enter the compression of each cylinder and see the spread, the percentage below the best cylinder, and which cylinders need a wet test or a leak-down test.
Open calculator →Injector leak-off / balance
Enter the leak-off (return) volume or flow of each injector and see which one deviates from the others. For common rail leak-off tests and petrol injector flow tests.
Open calculator →Injector duty cycle
Convert injector pulse width and engine speed into duty cycle, and see how close the injectors are to their limit.
Open calculator →Voltage drop in a cable
Calculate the voltage lost in a copper cable from its length, cross-section and current, and find the smallest cable that keeps the drop within limits.
Open calculator →Ohm's law
Enter any two of voltage, current, resistance or power and get the other two. Handy for checking sensors, coils, heaters and relays.
Open calculator →Battery drain (parasitic draw)
From the battery capacity and the measured parasitic draw, estimate how long the car can stand before it won't start, and whether the draw is normal.
Open calculator →Pressure converter
Convert boost, fuel, oil and vacuum pressures between bar, kPa, psi, mbar, kg/cm² and inHg, and between absolute and gauge pressure.
Open calculator →AWG to mm² converter
Convert American wire gauge (AWG) to cross-section in mm² and diameter, and find the nearest metric cable size.
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