Calculate breaker ratings for single phase circuits accurately. Include voltage, power factor, and continuous duty. Get clear results, examples, exports, and practical guidance fast.
| Application | Voltage | Load | Power Factor | Continuous | Suggested Breaker |
|---|---|---|---|---|---|
| Lighting Circuit | 230 V | 1200 W | 1.00 | Yes | 10 A |
| Water Heater | 230 V | 3000 W | 1.00 | Yes | 20 A |
| Window Air Conditioner | 230 V | 1500 W | 0.92 | No | 10 A |
| Single Phase Pump | 230 V | 12 A | 0.88 | No | 20 A |
For watt input: Current = (Load × Demand Factor) ÷ (Voltage × Power Factor × Efficiency).
For amp input: Current = Load Current × Demand Factor.
Continuous load adjustment: Adjusted Current = Base Current × 1.25.
Safety margin: Final Design Current = Adjusted Current × (1 + Safety Margin).
Breaker selection: Choose the next standard breaker equal to or above the final design current.
A single phase breaker size calculator helps estimate safe overcurrent protection. It supports fast planning for homes, shops, offices, and light industrial spaces. Proper breaker sizing reduces overheating risk. It also improves coordination between load current, cable rating, and device protection.
This calculator evaluates voltage, connected load, power factor, and efficiency. It also considers demand factor, safety margin, and continuous duty. That makes the estimate more useful than a basic amp chart. It gives a practical design current, not only a raw running current.
Continuous loads often need extra allowance. Many designers apply a 125 percent factor for loads that run for long periods. A safety margin can also help when temperature, startup stress, or future expansion may increase demand. These inputs help you avoid undersized breaker choices.
Single phase circuits that feed motors or compressors rarely operate at perfect power factor. Lower power factor raises current for the same useful output. That means breaker size can change even when wattage looks similar. This is why electrical planning should never rely on watts alone.
The result is a sizing guide. Final equipment selection should still follow local code, manufacturer data, ambient conditions, and conductor limits. A breaker protects wiring and equipment under defined conditions. If starting current is high, a different breaker curve or a dedicated motor solution may be better.
This page gives a simple way to compare loads and standard sizes. It also helps you create cleaner documentation with CSV and PDF exports. Use it during design review, maintenance planning, or estimating. It is especially helpful when you need a quick single phase breaker size estimate with clear assumptions.
Use this tool for branch circuits, small appliances, office equipment, heaters, pumps, and split unit loads. It works well during early sizing, retrofit checks, and maintenance visits. You can test several assumptions quickly. That helps you compare normal running current with a more conservative design current before work starts safely today.
It estimates a suitable single phase breaker size from electrical load data. It also shows design current, apparent power, starting current, and a conductor ampacity check.
Use whichever value you know best. If you know nameplate current, use amps. If you know equipment power, use watts and add realistic power factor and efficiency values.
Continuous loads can heat conductors and devices for longer periods. Many designs apply a 125 percent factor, which often increases the selected breaker size.
No. It is a planning tool. Final decisions should follow local electrical rules, installation methods, ambient temperature limits, and equipment manufacturer instructions.
Lower power factor increases line current for the same useful power. Higher current can push the design into the next standard breaker size.
The tool flags that condition because a larger breaker may not protect that conductor correctly. Review the cable size, insulation rating, and installation environment.
Yes, as a first estimate. Motor circuits can have high starting current, so always verify breaker curve, overload protection, and manufacturer guidance before final selection.
They export the result summary table shown after calculation. That makes it easier to save, share, or include the sizing result in job records.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.