Compute circuit voltage drop accurately. Test wire size, phase type, and run length. Plan efficient wiring with clear results and graphs.
The calculator uses conductor resistivity, length, current, and size to estimate voltage loss. It also suggests a larger cable when the drop exceeds your target.
| Voltage (V) | Current (A) | Length (m) | Material | Area (mm²) | Phase | Voltage Drop (V) | Drop (%) |
|---|---|---|---|---|---|---|---|
| 230 | 15 | 30 | Copper | 2.5 | Single | 6.21 | 2.70 |
| 120 | 20 | 18 | Copper | 4 | Single | 3.10 | 2.58 |
| 400 | 32 | 45 | Aluminum | 16 | Three | 5.39 | 1.35 |
| 415 | 50 | 70 | Copper | 25 | Three | 7.90 | 1.90 |
Single-phase circuit: Vdrop = I × Rtotal
Where: Rtotal = 2 × L × (ρ / A)
Three-phase circuit: Vdrop = √3 × I × R × power factor
Where: R = L × (ρ / A)
Percentage voltage drop: Drop % = (Vdrop / Vsupply) × 100
Receiving end voltage: Vend = Vsupply − Vdrop
Power loss estimate: Ploss = I²R for single-phase, or 3I²R for three-phase approximation.
In these formulas, I is current, L is one-way conductor length, ρ is resistivity, and A is conductor cross-sectional area.
Voltage drop is the loss of voltage along a conductor. It happens because every wire has resistance. Longer runs create more resistance. Smaller wires also increase resistance. As resistance rises, the delivered voltage falls. That can reduce equipment performance.
Current is a major factor. Higher current causes more drop. Cable length also matters. A longer path creates more resistance. Material changes the result too. Copper usually performs better than aluminum for the same size. Conductor area is also important. Thicker cables reduce resistance and limit loss.
Single-phase circuits use a return path. That is why the loop length is doubled. Three-phase systems use a different relationship. Their calculation often includes the square root of three and power factor. Choosing the right formula is important for accurate results.
Wire resistance rises with temperature. A hot conductor drops more voltage than a cool one. This calculator adjusts resistivity by temperature. That gives a more realistic estimate for practical installations.
Many designs aim to keep voltage drop low. A common target is 3 percent for branch circuits. Some full feeder and branch combinations use 5 percent as a total design goal. Exact limits may depend on project standards and local codes.
This calculator estimates voltage drop, receiving voltage, and power loss. It also compares the result to your target limit. If the drop is too high, it suggests a larger conductor size. That helps you make faster design decisions.
This tool is useful for planning and checking. Still, final electrical design should consider code rules, insulation ratings, installation method, ambient temperature, and grouping factors. Always verify the selected conductor with your required standards before installation.
Voltage drop is the decrease in electrical potential between the source and the load. It happens because wires resist current flow. Excessive drop can reduce motor torque, dim lights, and cause poor equipment operation.
Longer conductors have more resistance. More resistance means more voltage loss for the same current. That is why distant loads often need larger wire sizes to keep delivered voltage within the desired limit.
Larger conductor area lowers resistance. Lower resistance reduces voltage drop and heat loss. Increasing wire size is one of the most common ways to improve circuit performance over longer distances.
Copper has lower resistivity than aluminum. For the same size and length, copper usually produces less voltage drop. Aluminum can still work well, but it often needs a larger cross-sectional area.
Power factor reflects the relationship between real power and apparent power. In many practical three-phase voltage drop estimates, power factor influences the effective drop seen by the load.
Many designers use 3 percent as a common branch-circuit design target. Some systems use 5 percent total for feeder and branch circuit combined. Your exact project requirement may differ.
Yes. Conductor resistance rises as temperature increases. Higher resistance creates more voltage drop. Using temperature-adjusted resistivity gives a result that is closer to real operating conditions.
Use it as a design aid, not the only decision source. Final work should also check local code, insulation type, ampacity, installation conditions, protection devices, and safety requirements.
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.