PhonePrice360
Battery Life Calculator
Estimate screen-on time for any device using battery capacity and real-world usage – fast, accurate, free.
📘 How to use this calculator
1 Enter your device’s battery capacity (mAh) or pick a preset.
2 Choose a usage scenario (gaming, streaming, etc.) – this sets power draw.
3 Adjust battery efficiency if needed (older batteries are less efficient).
4 Get instant screen-on time, watt-hours, and comparison data.
Phones: 3.7V, Laptops: 7.4-11.1V
Estimated Screen-On Time
4h 5m
⏱️ 245 min
🔋 18.5 Wh
🔄 ~3.9 charges/day
~55%
Compare:
🔍 Understanding Screen-On Time & Battery Runtime
Screen-on time is the total hours your device's display stays active on a full charge. This PhonePrice360 battery life calculator uses your battery capacity (mAh), the typical power consumption of different activities, and a realistic efficiency factor to give you a trustworthy estimate.
Why accurate estimates matter
Knowing your approximate screen-on time helps you plan your day, compare phone models, and spot battery degradation. Our tool accounts for the fact that real batteries never deliver 100% of their rated capacity – heat, age, and discharge rate reduce usable energy.
Pro tips for longer battery life
- Lower screen brightness or use auto-brightness – the display is the #1 power drain.
- Enable dark mode on OLED screens; black pixels are off, saving up to 30% power.
- Close or limit background apps that constantly refresh.
- Use Wi‑Fi instead of mobile data when possible – cellular radios consume more.
- Keep your device cool; high temperatures degrade lithium-ion batteries faster.
❓ Frequently Asked Questions
How is screen-on time calculated? ▼
Screen-on time = (Battery mAh × Efficiency) ÷ Power Draw (mA). For instance, a 5000mAh battery at 90% efficiency with a 650mA video stream gives about 6.9 hours.
Does brightness really affect battery that much? ▼
Absolutely. Maximum brightness can consume 2‑4× more power than 50% brightness. On OLED displays, dark mode can reduce power by up to 30‑40%.
What is a typical phone battery efficiency? ▼
New phones usually have 90‑95% efficiency. After 1‑2 years of use, efficiency often drops to 80‑85%, meaning a 5000mAh battery behaves more like 4000‑4250mAh.
Can I use this calculator for laptops or tablets? ▼
Yes, just enter the device’s battery mAh and typical voltage (often 7.4V or 11.1V for laptops). The power consumption values are averages; you can use the “Custom” option for more precise numbers.
