20 Best Free Online Battery Life Calculator Websites

Here is a list of the best free online battery life calculator websites. The life of a battery depends on the power consumption or load on the battery. A battery life calculator allows you to figure out how long a battery would last per charge cycle. This can be helpful for a mobile phone, laptop, EV, or any other electrical component.

This post covers 20 free websites where you can estimate battery life. All these websites feature online calculators to determine the runtime of a given battery based on consumption. To do that, you have to provide the battery capacity and the power consumption. Most of these calculators go with the assumption that the battery is continuously draining until it is discharged. Some calculators can also factor in sleep time when there is no consumption. This is useful to provide better estimation for devices like smartphones, laptops, etc. With that said, let’s go through the post to check these calculators in detail. I hope you can find a calculator that can help you accurately estimate the runtime of a battery for your particular scenario.

My Favorite Online Battery Life Calculator

OmniCalculator.com is my favorite website on this list to calculate battery life online. This calculator helps you find the battery runtime while keeping a discharge safety percentage. It has an advanced mode that allows you to factor in the sleep mode to get an accurate result.

You can also check out our other lists of the best free online Battery Capacity Calculator websites, online EV Range Calculator websites, and online Carbon Footprint Calculator websites.

Overview Table:

Websites	Output	Battery Type	Change Unit
OmniCalculator.com	Battery Runtime	-	Fessible
BatteriesinaFlash.com	Battery Runtime/Capacity	Multiple Options	-
DigiKey.in	Battery Runtime	-	Fessible
AllAboutCircuits.com	Battery Runtime	-	Fessible
ElectricalTechnology.org	Battery Runtime	-	-
Electronicsforu.com	Battery Runtime	-	Fessible
CircuitDigest.com	Battery Runtime	-	Fessible
nCalculators.com	Battery Runtime	-	-
EasyCalculation.com	Battery Runtime	-	-
Calculator.academy	Battery Runtime/Capacity	-	Fessible
ReferenceDesigner.com	Battery Runtime	-	-
Utmel.com	Battery Runtime	-	Fessible
Mouser.in	Battery Runtime	-	-
Element14.com	Battery Runtime	-	-
Electrical4u.net	Battery Runtime	-	-
Gislite.com	Battery Runtime	-	-
WireKhoj.com	Battery Runtime	-	-
Byjus.com	Battery Runtime	-	-
EngineeringToolbox.com	Battery Runtime	-	-
TheEngineeringMindset.com	Battery Runtime	-	-

OmniCalculator.com

OmniCalculator.com offers a free online battery life calculator. This calculator helps you determine how long a battery would run. The calculator has a simple mode where it assumes that the battery runs continuously until it is discharged. For that, you have to provide the battery capacity and device consumption. You can also set a discharge safety percentage if you want. Then there is an advanced mode. It lets you analyze what happens if your device switches to sleep mode. In this mode, you can add the sleep and consumption during that time to get the battery runtime in hours. This calculator allows you to switch the measurement units for all applicable parameters. You can pick the unit of your choice and get the results as per your readings.

Highlights:

Output: Battery Runtime and Average Consumption.
Battery Type: N/A.
Additional Options: Inclusion of Sleep mode, Discharge Safety, and Awake time.
Change Unit: Yes, all parameters.

Home Page

BatteriesinaFlash.com

BatteriesinaFlash.com offers an online battery runtime calculator. This calculator can help you find the runtime of a battery based on consumption. To do that, you have to provide the battery capacity and device consumption. This calculator works for multiple battery types. You can select a certain type of battery to get a better prediction of the runtime. Alongside this calculator, this website has another calculator that does the reverse. In that calculator, you can add the device load and the runtime you require. Based on that, it tells what battery size you would need to get that runtime out of it.

Highlights:

Output: Battery Runtime.
Battery Type: Gel, Lead Acid, AGM, and others.
Additional Options: Calculates battery capacity for a required runtime.
Change Unit: No.

Home Page

DigiKey.in

DigiKey.in has a simple online battery life calculator. This calculator takes battery capacity and device consumption as input. You can pick the measurement unit of choice for each input and add the data. When you add both values, it instantly gives you the estimated battery life. It uses a battery illustration to show the battery life in hours. Above that, you get the formula used to get the battery life. There is also a dropdown box where you can pick the time format to get the battery life in hours, days, months, or years.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: Yes, all parameters.

Home Page

AllAboutCircuits.com

AllAboutCircuits.com has a free online battery life calculator. This calculator can help you find the running time of a battery in hours. To do that, you have to add the battery capacity and device load current into the calculator. You have to add the capacity in mAh whereas you get multiple options for the load covering A, kA, mA, uA, nA, and pA. You can add the load and set the correct unit for that. Then you can run the calculator to get the total running time.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: For load current only.

Home Page

ElectricalTechnology.org

ElectricalTechnology.org offers a free online battery life calculator. This calculator starts with the battery life formula and explains how it works. Later you get the actual calculator on the same web page. The calculator asks for battery capacity in mAH and device consumption in mA. You just have to enter those values in the respective boxes. Then simply click the “Calculate” button to get the battery life in hours.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

Electronicsforu.com

Electronicsforu.com also offers a free online battery life calculator. This simple calculator estimates the runtime of a battery based on the battery capacity and consumption. You get two input sections to add the respective value and one section for the output. Each section has a dropdown box next to it. You can use those sections to pick the desired measurement unit for each parameter. You can add the data and get the estimated battery life. Along with the numbers, this calculator also shows a battery illustration with the calculated battery runtime visualization.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: Yes, all parameters.

Home Page

CircuitDigest.com

CircuitDigest.com is a free website with various electrical and electronic online tools. It has a free online battery life calculator. This calculator calculates the battery life per charge in hours. To do that, you have to provide the total battery capacity and device consumption. You have the option to pick the measurement units as per your values. You can select the correct unit and then get the output.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: Yes, all parameters.

Home Page

nCalculators.com

nCalculators.com is a free website that offers a wide collection of calculators. There is a catalog of ELECTRICAL calculators listed in a dropdown menu. Among those, there is a mAh Battery Life calculator. This calculator takes battery capacity and device consumption in mAh. You can simply add the values to the calculator. When you do that, it instantly gives you battery life in hours. The measurement units are fixed in this calculator, you can not switch them. Thus you might have to convert your data accordingly.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

EasyCalculation.com

EasyCalculation.com also has a free online battery life calculator. This is a simple calculator that takes battery capacity rating and power consumption as input. It takes the battery capacity in mAh and the consumption in mA. You can simply add the values and run the calculation. Within a second, the calculator gives you the estimated battery life in hours.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

Calculator.academy

Calculator.academy has a free online battery runtime calculator. You can use this calculator to estimate a battery life per charge. The calculator shows the formula for the calculation followed by the input fields. It has three fields covering battery capacity, power usage, and battery runtime. The unit for battery capacity is fixed to Ah and time to hours. Whereas it lets you pick the power usage limit from a list of options. The unique thing about this calculator is that you can add any two parameters to calculate the third one. So, you can calculate battery runtime from capacity and usage, usage from capacity and runtime, and capacity from runtime and usage.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: Calculates battery capacity or power usage from given runtime.
Change Unit: Yes, all parameters.

Home Page

ReferenceDesigner.com

ReferenceDesigner.com is a free website with an online battery life calculator. This calculator has a very simple interface with two input boxes and one output box. The input boxes are for battery capacity and current. You have to enter the battery capacity in Ah and the current in Amp. With those two inputs, the calculator gets you the battery life in hours. Apart from that, the web page also features a video that explains battery life calculation.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: Yes, all parameters.

Home Page

Utmel.com

Utmel.com has a free online battery life calculator that estimates the battery runtime based on battery capacity and system usage. This calculator provides dropdown boxes next to battery capacity and system usage. You can use those dropdowns to set the correct measurement units for your input. After that, when you add the values, this gets you the battery life. By default, it shows the battery life in hours but you can change that to get it in days, months, weeks, and years.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: Yes, all parameters.

Home Page

Mouser.in

Mouser.in offers a free online battery life calculator. This calculator has fixed measurement units for all the parameters. However, it offers two configurations to calculate the runtime. The first configuration determines the battery life from battery capacity and device consumption. It also calculates the consumption rate. The second configuration calculates the runtime from Ampere Hours and Load in Watts. Based on the readings you have, you can use either configuration to estimate the battery life or runtime.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: Calculates the consumption rate.
Change Unit: No.

Home Page

Element14.com

Element14.com has a free online battery life calculator. This calculator is quite simple. To calculate the battery life per charge cycle, it requires two parameters; battery capacity in mAh and device consumption in mA. You can add both these values into the calculator and then run the calculator to get the result. When you do that, it gives you the battery runtime in hours. The web page also shows the battery life formula for the calculation.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

Electrical4u.net

Electrical4u.net has a free online battery life calculator that you can use to estimate the total runtime of a battery per charge cycle. Along with the battery capacity and load, it also takes the battery voltage into account. You have to provide the battery capacity in Ah, load in Watts, and battery capacity in Volts. You can add these three values and get the battery life in hours.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

Gislite.com

Gislite.com offers a comprehensive battery life calculator. Similar to all other calculators, this one also determines the battery life from battery capacity and consumption. Along with that, it also factors in the working temperature into account. To estimate the battery life, you have to provide the working temperature and pre-failure time at a given temperature. Then you have to add the typical and maximum consumption in nA. With that, the calculator gets you the battery life in days and years. It also gives you battery life considering self-discharging over time.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: Factors in working temperature and self-discharging.
Change Unit: No.

Home Page

WireKhoj.com

WireKhoj.com is another free website to determine battery life online. This website has a simple calculator where you can add the battery capacity in Ah and load in Watts. Along with that, you also have to provide the battery voltage in Volts. With these three parameters, the calculator gets you the total battery life per charge cycle. It shows the battery life in hours.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

Byjus.com

Byjus.com, an online learning platform also offers a free online battery life calculator. This calculator has three parameters covering battery life, load current, and battery capacity. You can provide any two parameters to get the value of the missing parameter. It uses mAh for battery capacity, mA for load current, and hours for battery life. After adding any two parameters, put ‘x’ in the missing parameter. Then run the calculator to get the respective value.

Highlights:

Output: Battery Runtime and vice versa.
Battery Type: N/A.
Additional Options: N/A.
Change Unit: No.

Home Page

EngineeringToolbox.com

EngineeringToolbox.com has an online calculator to determine the battery life of a rechargeable battery. The calculator features a comparison chart of the properties of various types of rechargeable batteries. Below that there are inputs for battery capacity (Ah, mAh) and device consumption (A, mA). Along with that, you have to also provide the usable battery energy in percentage. With that, the calculator estimates the total battery life per charge cycle.

Highlights:

Output: Battery Runtime.
Battery Type: N/A.
Additional Options: Set usable energy percentage.
Change Unit: No.

Home Page

TheEngineeringMindset.com

TheEngineeringMindset.com is yet another website with an online battery life calculator. It is actually a combination of two calculators; one to estimate battery life and one to estimate battery capacity. With the known values of battery capacity in mAh and circuit current in mA, you can calculate battery life in hours. And with the known values of battery life in hours and circuit current in mA, you can calculate the required battery capacity in mAh.