The CapacitorCalculator.com capacitor calculators — code decoder, unit conversion, series/parallel, plate geometry, and HVAC under-load — produce planning estimates built on the values you enter and the assumptions they make. These are not a component specification, an engineering design, or a stamped document. Review these points to understand the limits of the tools and your responsibilities before the first part goes in the cart — or the first terminal gets touched.
The math is exact for the part you describe — so read the marking carefully, keep the meter and the manufacturer’s data sheet in the loop, discharge before you touch, and let a qualified professional make the final call.
Capacitors store energy — E = ½CV² — and hold it long after equipment is unplugged. Discharge through an appropriate resistor and verify zero volts with a meter before touching terminals. Estimates are a starting point: verify the marking, confirm the datasheet, and check your local electrical code before ordering or working. If any doubt exists, stop and consult a qualified engineer, electrician, or the component manufacturer.
The arithmetic on this site is exact for the part you describe. These are the places where the description and the real component drift apart — each one fixable before the parts order, expensive or dangerous after it.
An old motor label reads "35 mF". The tech orders 35 millifarads — a 35,000 µF photoflash-grade can — when the label, written in pre-1960s convention, meant 35 µF. Three orders of magnitude hide in one letter. The conversion calculator shows all five units at once precisely so this cannot slip through silently.
A one-second reset delay is built around a 104 ceramic and a resistor — the math says 1.0 s. But a ±20% M-grade part, drifting further with temperature and voltage, delivers anywhere from roughly 0.75 to 1.25 s in the field, and the 'broken' product is simply a wrong tolerance grade. Check the tolerance table before the value ships.
A filter bank is unplugged 'yesterday' — its 450 V electrolytics still hold a full charge, because a capacitor's whole job is holding energy. A screwdriver across the terminals welds itself, and the diagnosis session ends in the emergency room. Discharge through a resistor, verify with a meter, then work — every time, no exceptions.
Every point is stated in full — no clicking required. Each one shapes how the results should be used.
Every decoded value, unit conversion, series/parallel total, plate-geometry result, charge and energy figure, and under-load capacitance on CapacitorCalculator.com is computed from the markings, values, and assumptions you enter. These outputs are planning and diagnostic figures to help you select a component, size a bank, or diagnose a motor circuit. They are not a component specification, an engineering design, or a professionally stamped document.
This tool does not replace a licensed electrician, an electronics engineer, an HVAC contractor, or your local electrical inspector. Decisions about voltage ratings in mains-referenced circuits, X and Y safety-capacitor classes, creepage and clearance, discharge circuits, and HVAC electrical work are professional and regulatory decisions the calculator does not make. When a task touches mains voltage, refrigerant systems, or anything safety-rated — retain qualified people who can design, inspect, and sign off.
The calculator uses standard formulas and published reference values, but the controlling documents are physical: the manufacturer's data sheet for the exact part you hold, the EIA marking standard, the component safety classes that apply to your circuit, and your local electrical code and its amendments. Where the tool and the datasheet disagree, the datasheet wins — every time and by design.
A marking read at an angle, a 1 mistaken for a 7, a code entered where the trailing letter is actually part of the date lot code — each of these moves the answer. Read the marking straight on under good light, confirm the value with a capacitance meter when the part matters, and remember that a decoded value is a hypothesis the meter should confirm before you rely on it.
The energy a capacitor stores — E = ½CV² — does not disappear when the equipment is switched off. Large electrolytics in power supplies, motor run capacitors, and microwave-oven caps can hold a lethal charge long after unplugging. Always discharge capacitors through an appropriate bleed resistor, verify zero volts with a meter, and follow safe discharge practice before touching terminals. No calculation on this site substitutes for that procedure.
A nominal value is not the value in your circuit. A ±20% ceramic can legally sit 20% off its marking, and Class II dielectrics (X7R, Y5V) lose further capacitance under applied voltage, with temperature, and with age — a 10 µF X7R can measure half that at rated voltage and temperature. For timing and filtering, the grade you choose matters more than the nominal value; the tolerance tables on this site exist so you choose deliberately.
The 25-material table behind the plate calculator carries typical published relative permittivity values — air, PTFE, polypropylene, FR4, glass, mica, ceramics, and the rest. Real batches vary with composition, temperature, and frequency, and fringing fields make real capacitors slightly larger than the ideal formula. Treat plate-calculator outputs as design guidance, then confirm the built part with a measurement.
The HVAC under-load method requires measuring amps and volts on a running motor circuit — line voltage, moving parts, and energized terminals in the same enclosure. Only qualified personnel should perform it, using meters rated for the voltage category, following lock-out and PPE requirements, and never bypassing a capacitor's safety features or run characteristics. A verdict from this tool supports a professional diagnosis; it is not one.
CapacitorCalculator.com is provided "as is" without warranties of accuracy, fitness for a particular purpose, or merchantability. Always verify decoded values, bank totals, geometry results, and under-load readings against your own measurements, the manufacturer's data sheet, and your local electrical code. Follow the bench rule: discharge first, measure twice, and never let an unverified number become a purchase order or a diagnosis.
A quick breakdown of where the calculator’s job ends, what authorities and qualified professionals must decide, and what you must verify before the part order is placed or the panel is opened.
Planning estimates, not stamped specsPhoto: UnsplashA condenser fan misbehaves; the run capacitor’s label reads 35 µF and the part looks perfect — no bulge, no leak. Under load, though, the meter shows 4.1 A across 315 V, which works out to roughly 26.5 µF — about 24% below rating, far past any replace threshold. A capacitance check on the bench might even read closer to spec at low voltage; the motor only exposes the real story under its operating load. The replacement fixes the complaint the “looks fine” inspection missed.
The calculator gives you honest arithmetic about the readings you enter — which is exactly why the readings must be taken safely, on the real equipment, with rated meters, and judged against the label and the trade’s thresholds. Use the tool to get into the right conversation with your engineer or service manager, not to end it.
The same calculation can be responsible planning or a reckless shortcut — the difference is what it is used to decide. Two lists, no ambiguity.
Read the columns together: every sanctioned use has a misuse that looks almost identical right up to the point where someone relies on the number instead of verifying it with the meter, the datasheet, and the code book.
By using CapacitorCalculator.com, you acknowledge that you have read, understood, and agree to this disclaimer. The capacitor calculators — code decoding, unit conversion, series/parallel totals, plate geometry, charge and energy figures, and under-load verdicts — are provided for planning and educational purposes only. Capacitor Calculator is not liable for misdecoded values, wrong component selection, circuit malfunctions, equipment damage, electrical shock or injury, fire, failed inspections, HVAC system failures, or costs that differ from projections arising from their use. When in doubt, verify against your own measurements, the manufacturer’s data sheet, and your local electrical code. If you do not agree, please do not use the tools.