Battery Amp-Hour (Ah) Calculator

Easily calculate the amp-hour (Ah) of your battery. Enter voltage, current, power, and usage time to get accurate results. Adjust efficiency for realistic estimates.
Formulas: Ah = Current × Time OR Ah = Power × Time ÷ Voltage

How to Use

• If you know current (A) and time (h), use: Ah = Current × Time
• If you know power (W) and voltage (V), use: Ah = Power × Time ÷ Voltage
• Efficiency (%) can be entered to estimate real usable capacity.
• Result is automatically displayed in Ah and mAh.

Example Calculations

• 12V battery, 5A, 3 hours → 15 Ah (15,000 mAh)
• 60W device, 12V battery, 3 hours → 15 Ah (15,000 mAh)
• Efficiency 90% applied → 13.5 Ah usable capacity

Battery Tips & Knowledge

• In series connection, voltages add, Ah stays the same.
• In parallel connection, Ah adds, voltage stays the same.
• Different battery types (Li-ion, Lead Acid, NiMH) have different efficiencies and self-discharge rates.
• Always consider temperature effects on battery capacity.

Frequently Asked Questions

1. How do I calculate battery amp hours (Ah)?

• You can calculate Ah using Current × Time (Ah = A × h) if you know the current, or Power × Time ÷ Voltage (Ah = W × h ÷ V) if you know power and voltage.

1. Can I calculate Ah using only the battery power?

• Yes, if you know the battery’s power in watts and its voltage, Ah = Power × Time ÷ Voltage.

1. Does the calculator consider battery efficiency?

• Yes, enter an efficiency percentage to estimate real usable capacity.

1. Can I see the result in mAh?

• Yes, results are automatically converted: 1 Ah = 1000 mAh.

Check out our battery products and other calculators to find the right solution for your needs.