Calculator 05 / Shop Tools
Shop Tools
Torque unit conversion, Ohm's Law, and battery amp-hour runtime — the everyday math that comes up on the bench.
How this calculator works
Torque conversion uses standard, exact SI conversion factors. Ohm's Law and power together describe how voltage, current, resistance, and power relate in any DC circuit — handy for checking wire gauge against a fuse rating, sizing a battery for an accessory, or diagnosing why something's drawing more current than expected. Battery runtime assumes a constant, steady load — real-world runtime is usually a bit less once you factor in battery age, temperature, and voltage sag under load.
Why not discharge a battery to 100%?
Deep discharge shortens the life of most lead-acid batteries significantly — many manufacturers recommend not routinely going below 50% state of charge, with 80% usable capacity as a common conservative planning number. Lithium (LiFePO4) batteries tolerate deeper discharge much better.
Does Ohm's Law apply to AC circuits too?
The basic V=IR relationship holds for resistive AC loads, but AC circuits with motors, inductors, or capacitors involve additional factors (impedance, power factor) that this simple calculator doesn't account for.
Estimates only. For torque specs, always use your vehicle or equipment manufacturer's exact figures — this tool converts units, it doesn't tell you what spec to use.