Can I Replace a 40 5 Capacitor With a 45 5 [ Explained]

The difference between 40+5 F and 45+5 F capacitors is not much worth saying. So, the effect of replacement with one another should not affect much. But, please adhere to the factors namely voltage rating, size, and the functionalities of the capacitors.

For each circuit, a specific capacitor is present. It is suggested that a capacitor of the right value be used to make sure the circuit operates properly. The energy consumption of a larger capacitor is higher, increasing the risk of an overheating issue.

Can I Replace a 40 5 Capacitor With a 45 5

Is It Safe to Use 45 5 Capacitor Instead of 40 5

It is the capacitance values of the capacitors that are indicated by 40+5 and 45+5. Here, the first number is for the capacitance value for the main device, and the second number indicates its capacitance value for a different device, like a fan motor.

Actually, a 40 5 capacitor can be replaced with a 45 5. But the latter comes with a slight risk of overheating.

Voltage rating

There is a maximum voltage that capacitors can withstand without breaking down or getting damaged. Make sure that the replacement capacitor has a voltage rating that is equal to or higher than the original capacitor. 

It may happen that the employed capacitor is not able to withstand if its voltage rating is lower. This often distresses the functionality and eventually damages the system. So, the best is to use a capacitor with exactly the same rating. 

Physical size

You will find several forms, sizes, and styles of capacitors. So these things matter when replacing one. The new capacitor should not take up more space than the one to be replaced. You need to ensure this since otherwise other circuit elements and their solderings may get affected due to nearby overheating.


Capacitors occasionally serve many purposes. The second number, the additional capacitance value, denotes an extra capacitance for a particular use, such as powering a fan motor or giving a boost during starting. 

It’s critical to confirm that the replacement capacitor is capable of performing the same task as the original. Make sure the new capacitor gives the same or similar functionality if the extra capacitance is essential to the device’s operation.

Capacitance Difference

Using the formulas for capacitance in series and parallel connections, we can assess the effect on the performance of the circuit after swapping a 40+5 F capacitor for a 45+5 F capacitor.

The reciprocal of the sum of the reciprocals of the individual capacitances for capacitors in parallel yields the total capacitance (C):

Total 1/C = 1/C1 + 1/C2

Let’s say, in this instance that we have two capacitors connected in parallel, C1 being 40 F and C2 being 5 F.

1/C = 1/40 + 1/5

1/C = (1/40 + 8/40) 

1/C = 9/40

Total Capacitance = 40/9 ≈ 4.44 µF

The total capacitance (C) for capacitors connected in series is the sum of the individual capacitances:

Total C = C1 + C2

With the identical values, we have:

Total = 40 + 5 = 45 µF

Now using the same formula for the parallel connection regarding the 45 5 capacitor we get the total capacitance ≈ 4.5 µF and for the series connection 50 µF.

These calculations suggest that switching from a 40+5F capacitor to a 45+5F capacitor would result in a somewhat greater total capacitance in both series and parallel connections. It’s crucial to remember that these calculations are based on perfect capacitors with exact values. 

Tolerances and other factors may influence capacitance levels in real-world applications. However, under most circumstances, the slight variation between 40+5 °F and 45+5 °F shouldn’t be problematic. However, the risk of overheating may reduce the lifespan of the capacitor.

Frequently Asked Questions and Answers

Can I Substitute a Capacitor With One Rated at a Lower Voltage?

To prevent any failures or damage, it’s crucial to utilize a replacement capacitor with the same voltage rating or greater. So, it is not recommended.

Should I Get Advice From a Specialist Before Changing a Capacitor?

It is advised to seek advice from a qualified technician or the device’s maker if you have any questions or concerns or if the product is still covered under warranty.


The tiny variation in capacitance values makes it generally permissible to swap a 40+5 F capacitor out for a 45+5 F capacitor. To ensure compatibility with the circuit and device requirements, it is essential to take into account additional elements including voltage rating, physical size, and functionality. 

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