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Cable and Wire Size Calculator – Copper and Aluminum

Copper and Aluminum Cable and Wire Sizing Calculator

Several factors influence the selection of cable and wire sizes in electrical installations. One crucial factor is the current carrying capacity required for the intended application. The magnitude of the electrical load, measured in amperes, determines the size of the conductors needed to safely carry and distribute the current.

Voltage drop is another critical consideration, particularly for long-distance installations, where excessive voltage drop can lead to operational inefficiencies.

Temperature conditions in the environment also play a role, as higher temperatures can affect the conductor’s capacity and insulation properties. Additionally, the type of insulation and the installation method impact cable and wire sizing, ensuring compliance with safety codes and standards.

The combination of these factors requires careful consideration to optimize the performance, safety, and efficiency of electrical systems.

In our previous tutorial, we have discussed in detail the topic of how to calculate the proper wire size for electrical wiring installations. If you are allergic to those complex calculations, you may use the following copper and aluminum wire size calculator to properly size any wire for single phase and three-phase load circuits.

Wire Cable Size Calculator-Copper-Aluminum-AWG

Calculating Wire/Cable Size formula for single Phase Circuits

Wire Circular mils = 2 x ρ x I x L / (% Allowable Voltage drop of source voltage)  

Calculating Wire/Cable Size formula for Three Phase Circuits

Wire Circular mils = √3 x 2 x ρ x I x L / (% Allowable Voltage drop of source voltage)  


Note: the Value of ρ = Specific resistance or resistivity of Conductor is used here for copper and aluminum is 11.2 and 17.4 respectively at 53° C (127° F)

  • Note: See the ‘Good to Know’ section right after the calculator for a proper and clear understanding of the terms used in wire sizing.

Enter the values, And click on calculate. Result will shows the required quantity.

You must know Input Values Result
Source Voltage (V):  110V   120V   208V  
 220V   230V   240V  
 277V   440V   480V  
Number of Phases:  Single-Phase     Three-Phase
Current in Amp (A):
One Way Distance (feet):
Allowable (VD)   3% of VS    5% of VS
Or Select (VD)     V in Volts
Wire Size
Copper        Aluminum       

Good to Know:

If the wire size is greater than all gauges (i.e 0000 is largest one size of wire in), then electrical engineer measure it in CM, kCM or MCM instead of inches, because inch is a small unit of these kinds of  wires. Where;

circular mil (CM) is a unit of circular area with a diameter of one mil (one thousandth of an inch). It corresponds to 5.067×10-4 mm².


1000 CM (circular mils) = 1 MCM or 1 kcmil = 0.5067 mm², so 2 kcmil.

It is a unit for referring to the area of a wire with a circular cross section.

Related Posts & Calculators:

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      1. 4mm cable is the size acceptable ,but again depending on the hp of the AC if is like 1-1.5 hp you can use 2.5mm cable I believe it will be ok

  1. above show how to calculate the size of the cable and wire bt it is theoretical practical not working when i input the data value single phase 230 current 5 A single phase 10 feet voltage drop take 2.5 v please solve my problem

  2. sir
    we want to feed 3phase supply to 70 ton air-conditioning load. what will be the size of cable(3 phase) require to feed the 70 ton A.C. load.

    1. 35mm copper cable if lenth is less than 50 meter

      and if lenth is above than 50 meter the cable size is 50mm

      the standard voltage is 3 phase 400 volt 50HZ

    1. I have 377 Ampere 3-phase connected load to be sourced from 250 KVA 11 KV/440 Volt Distribution Transformer at a distance of 115 metres. What minimum size of 3.5 core Aluminium armoured cable will be suitable for my use.

  3. Sir, I have plan to install 8.3 ton three phase a/c distance between a/c and panel is 45′ voltage drop is 3%. which is the correct size of copper wire i have to use.

    1. A 30m long twin PVC installation cable carrying current from a switch bulb in a domestic installation to a 4kv electric heater.
      (1) Determine the minimum size of cable with reference to the electrical installation regulation.
      (2) calculate the size of the cable for the light of 120m distance long is to be lighted by 40w lamp

    1. Hello,
      I need cables and wire calculations for aluminium and copper, table for diameters and Amp. Thanks.

  4. Hi Everyone,
    Kindly give me guidance for the calculation of cable size.
    Suppose I have 40A load and 25KA is rating and I don’t have specified lentgh of cable,Voltage ratings but I need to give just size of cable for Phase conductor and ECC is there any way to calculate it directly using some direct formula…?

  5. sir,
    what is the distance between high tension electric wire to any building just like ware house, residential building, any factory. thanks

  6. What should be the cable size for the following conditions.
    1. amps: 3000
    2. 3 phase, 440 V
    3. Distance : 100 m
    3. Laid in trunking, copper cable

    Appreciate if you could suggest a cable size?

    Thank You

  7. a generator feeding 420 volt to 380/420 transformer cabble length is 1300 meter.load is of 200 how to find voltage drop and which cable suits alluminium or copper . and find the diameter of both. please help me out..

  8. Electric cable size wise how much load can be take. I need chart minimum 4 numbers of cable size i.e 1mm, 1.5mm, 2.5mm and 6mm

    Cable 1mm = ?? Amp or, ?? W


  9. What should be the cable size for the following conditions.
    1. amps: 250
    2. 3 phase, 440 V
    3. Distance : 100 m
    3. Laid in trunking, copper and Aluminumcable

    Appreciate if you could suggest a cable size?

    Thank You

  10. Sir, I have plan to install 4 no’s of 4 ton three phase a/c distance between a/c and panel is 45′ voltage drop is 3%. which is the correct size of copper wire i have to use.

  11. sir we have 3 kw hot plate it cable is burnout i want to replace it cable high tempatur fiber insulation type length 1mtr only plse helpe me

  12. Hi
    How would I determine the size of the main cable to feed 12 houses from a transformer to the main distribution box.
    Single phase
    45Amp per house x 12
    150 Meter (500Feet)
    Much appreciated

  13. Run is 300 ft. 120/240 volt system 170 amps 3% V.D.
    Using wire size 3/0 copper or 250MCM Aluminum.

    Is this the correct wire sizing for this project.

  14. Sir.cable & wire(aluminum or copper) how to selection. the load for example..10kw,50kw,125kw,25okw etc. i need to simple formula reply please.

  15. Hi
    Kindly help me for selection of wire for my new industry.
    actually my all machine and acceries load is about 20 kw. in future i will add another 20 kw. machine wire from control board i know. but i don’t know from eb to main board and control board for 40kw. Above calculator is very useful for single phase. but i dont know how to enter voltage range for 3 phase. because each phase has 220v (L to N). i dont know exactly what i have to enter in 3phase..(415v or 220v). kindly help me. distance about 110feet.

  16. respected sir
    I want information how I m find cable rating or amp or electrical network. how to decide cable rating 70 ton air conditioning in amp..

  17. Hi Dears,
    I have a new Air-conditioner is working on power 220V/60Hz and my country’s power is 220V/50Hz, my questions are how can fix it this air-condition on (220V/50Hz)? Is there an easy converter or electronic board/ diagram can I fix this issue by myself? If I run this air-condition on 50Hz what will happen ? is there any simple or shortest way for fix this problem.

    Please, nobody answer on my questions if he is not qualifying and professional in Electric because I have information but I need assistance from qualifying and professional people kindly?

    Thanks in Advance

    1. Yes it can work..they normally have a tolerance and work on 50/60 hz.
      That’s the times it alternates in a should work normally.

  18. I like your work guys,

    But what is this AWG thing now? I am in South Africa and I need the conductor size in mm for each wire, please help.

  19. If you may provide instant D.C. Cable size calculator if given: 12;24;48 Voltage D.C. and load current with cable length?

  20. Require to run a 3 phase / 50 Hz, 2 hp submersible pump
    at 1 km distance from the source of current supply.

    Appreciate advice re cable cross section, type, etc.

  21. Sir, i have to install a machine of about 250 Amps.. and the distance is about 100 meters… What should be the size of aluminum cable in mm2… Plz answer…

  22. Sir,
    I want to know 350 kw star delta motor what type of cable size reqrequired copper or aluminium. With gland size both.
    D. China kumar
    Mega paper

  23. I want to know how to calculate for select cable size for 3phase and single phase?
    I want to know a formula

    1. the formula calculate cable size in single phase
      2xPx1xL(%allowable voltage drop of source voltage
      In three phase
      3under root x 2xPx1xL(%allowable drop of soucrce voltage

  24. we have 1600kva transformer and connected with 95mm2 xlp cable lenght 500mtr.Due to excess load we will replace this transformer with 2000kva.what will be the cable size with 500mtr lenght xlp cable.

  25. Thank you for providing this, I was really struggling with cable sizes and this has been an absolute life saver.

  26. sir we need 70KVA power for our office. 3 Phase 5 wire to be taken.

    What gauge of copper / aluminum cable is needed for 80 feet distance.

  27. I want the wire thickness and heat it may produce for 500kva load at 480v . Lets take the current to be 700amp approx.

  28. sir if the total load is 60 to 70 amp. what type of cable should i select? Distance is less than 15 meter. is 10sq mm armoured cable is sufficient?

  29. What size of cable for 25kva dg, distance 100 meter, aluminium cable or copper cable, please….. if it is aluminium cable what is the size or copper…

  30. You write:
    “A circular mil (CM) is a unit of circular area with a diameter of one mil (one thousandth of an inch). It corresponds to 5.067×10-4 mm².


    1000 CM (circular mils) = 1 MCM or 1 kcmil = 0.5067 mm², so 2 kcmil.”
    You may want to look at that last sentence: 1kcmil=0.5067mm2 = 2kcmil?

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