Camera Power Supply Size Calculator
What the Camera Power Supply Size Calculator does
The Camera Power Supply Size Calculator estimates the minimum continuous output current needed to power a group of cameras from a shared supply. It combines the cameras’ maximum power draw with any additional load, applies a capacity margin, and divides the total by the required supply voltage.
The result is shown in amperes (A) as Minimum Supply Current. Use it as a starting point when comparing compatible power supplies for a security camera installation. Choose a supply with a continuous current rating at least as high as the unrounded result, while also checking voltage, polarity, connectors, startup requirements, and cable voltage drop.
The calculator assumes that all cameras entered have the same maximum power draw and use a compatible supply voltage. It also assumes that any additional load is supplied at that same voltage. The default values are illustrative, so replace them with information from your equipment specifications.
How to use the Camera Power Supply Size Calculator
Gather the power specifications for your cameras and any other devices that will share the supply. Then enter the following values:
- Number of cameras: Enter the number of cameras connected to the shared supply. The calculator accepts whole numbers from 1 to 256.
- Maximum power per camera (W): Enter the maximum power draw of one camera in watts. Use the manufacturer’s maximum specification, including features such as infrared illumination or heating where applicable. The calculator applies this value to every camera.
- Additional load (W): Enter the combined power draw of other equipment sharing the same supply and voltage. Enter zero if there is no additional load.
- Required supply voltage (V): Enter the voltage required by the connected equipment, such as 12 V or 24 V. Confirm that every device is compatible with that voltage.
- Capacity margin (%): Enter the extra capacity you want to allow above the calculated load. This is a user-selected assumption, not a universal recommendation.
Read the result in amperes and compare it with the power supply’s continuous output current rating. The displayed result is rounded to two decimal places, so choose a rating that is at least as high as the underlying unrounded value.
If your cameras have different maximum power draws, the single per-camera input cannot represent each one individually. You can use the highest camera rating for every camera as a conservative estimate, or calculate the combined load separately and check the supply requirements against the equipment specifications.
How the Camera Power Supply Size Calculator formula works
The formula uses the electrical relationship power = voltage × current. It first calculates the total load in watts, adds the selected margin, and then converts the adjusted power requirement to current at the entered voltage:
Minimum Supply Current (A) = [(Number of cameras × Maximum power per camera + Additional load) × (1 + Capacity margin ÷ 100)] ÷ Required supply voltage
The margin applies to the combined camera and additional load. For example, a 25% margin multiplies that combined load by 1.25. A margin of 0% leaves the calculated load unchanged.
Worked example
Suppose you have four cameras rated at a maximum of 10 W each, plus 10 W of additional equipment. All devices use a compatible 12 V supply, and you select a 25% capacity margin:
- Camera load: 4 × 10 W = 40 W
- Combined load: 40 W + 10 W = 50 W
- Load with margin: 50 W × 1.25 = 62.5 W
- Minimum Supply Current: 62.5 W ÷ 12 V = 5.2083 A
The calculator displays 5.21 A. A compatible 12 V supply must have a continuous output current rating of at least the unrounded 5.2083 A result. In practice, select an available rating above that value and check the other installation requirements before purchasing.
Use cases for the Camera Power Supply Size Calculator
A shared supply can simplify the power arrangement for several security cameras, but its capacity must cover the connected load. This calculator can help with several planning tasks:
- New camera installations: Estimate the continuous current requirement before selecting a supply for a group of cameras with matching power specifications.
- Adding cameras: Recalculate the total when expanding an existing system, then compare the result with the current supply’s continuous rating.
- Accounting for accessories: Include a known additional load that shares the same voltage and supply, rather than sizing the supply around the cameras alone.
- Comparing compatible supplies: Use the estimated current as one criterion when reviewing supplies with the required voltage, connectors, and output configuration.
- Planning a margin: See how a chosen percentage changes the current requirement. The appropriate allowance depends on the equipment and installation.
For readers of thebestsecuritycameras.com, the estimate is especially useful when planning cameras whose power draw changes with operating conditions. A camera may use more power when its night vision, heater, motor, or other features are active. Check the maximum figures in its documentation instead of relying only on a typical daytime draw.
Other factors to consider when calculating Minimum Supply Current
Voltage compatibility comes first. A higher current rating does not make a supply with the wrong output voltage suitable. Check the required voltage and whether the equipment needs AC or DC power. For DC connections, verify connector size and polarity as well.
Startup and surge loads need a separate check. The result estimates continuous current from the values entered. It does not determine whether a supply can handle a brief startup surge or other transient demand. Review the camera and supply specifications, particularly when motors, heaters, or several devices may start together.
Individual outputs may have their own limits. A multi-output power distribution unit can have a sufficient total rating while an individual output, fuse, or channel is undersized for its connected camera. Check both the overall supply rating and each relevant output rating.
Long cables can cause voltage drop. Resistance in the cable can reduce the voltage reaching a camera, especially over long runs or with undersized conductors. The calculator does not model cable length or wire size. Check the voltage at the camera against its allowable range and follow the equipment manufacturer’s installation guidance.
Power over Ethernet requires additional checks. If your cameras use PoE, confirm compatibility with the applicable PoE standard, the power available at each port, and the total switch or injector power budget. This current calculation alone does not establish PoE compatibility or account for every power delivery constraint.
Finally, treat the capacity margin as a planning assumption. A larger margin increases the calculated minimum, but it does not replace checks for surge capability, wiring, environmental conditions, or the supply manufacturer’s operating limits.
Frequently asked questions
What size power supply do I need for four security cameras?
The answer depends on each camera’s maximum wattage, the required voltage, any additional load, and your selected margin. In the calculator’s illustrative example, four 10 W cameras plus a 10 W additional load at 12 V with a 25% margin produce a displayed result of 5.21 A. Select a compatible supply rated at or above the unrounded result of approximately 5.2083 A.
Can I use a power supply with a higher amp rating?
A compatible supply can have a continuous current rating higher than the calculated requirement; the connected equipment draws the current it needs. The output voltage, AC or DC type, polarity, connectors, and other specifications must still match the equipment.
What capacity margin should I enter?
Enter a margin suited to your equipment and installation. The default 25% is an illustrative assumption, not a universal rule. Check manufacturer guidance and consider operating conditions and potential future loads. Startup surges and cable voltage drop still require separate checks.
Can I use the calculator for cameras with different wattages?
The calculator applies one maximum wattage to every camera. Using the highest camera wattage for all of them can provide a conservative estimate, but it may overstate the total. For a more exact assessment, add the individual maximum loads separately and verify the supply against that total and your chosen margin.
Does the result include cable losses or PoE requirements?
No. The result is based on the entered loads, voltage, and margin. Check cable voltage drop separately. For PoE cameras, also verify the PoE standard, per-port capacity, and total switch or injector power budget.