Battery Cost Per Amp-Hour Calculator

Sticker price divided by rated amp-hours is only the first comparison. A battery's usable depth of discharge and expected cycle life change how much work you get for the money. Enter the figures from the product documentation when available; this tool does not assume one chemistry always wins.

• Rated cost: $45 ÷ 18 = $2.50 per rated Ah.
• Usable capacity: 18 × 0.50 = 9 Ah.
• Usable cost: $45 ÷ 9 = $5.00 per usable Ah.
• Lifetime delivered capacity: 9 × 500 = 4,500 Ah.
• Lifetime cost: $45 ÷ 4,500 = $0.01 per lifetime delivered Ah when rounded to cents.

Rated Ah is a nameplate capacity measured under specified conditions. Usable Ah is the portion you choose to draw before recharge; the correct limit depends on the battery maker and system design. Cycle life is meaningful only when the test depth, temperature, cutoff voltage, and end-of-life definition are comparable.

Also account for standby draw, cold weather, charging quality, wiring loss, warranty, physical fit, and whether you need one larger battery or several matched batteries. A larger bank can reduce the fraction used each day, but it does not repair a parasitic load or poor charger.

• Comparing rated Ah while ignoring usable depth.
• Using a marketing cycle number without checking its test conditions.
• Assuming service years from a generic chemistry rule instead of the manual.
• Ignoring shipping, core charges, temperature, and the battery's charging requirements.
• Adding one unmatched battery to an older parallel bank.

If service years is blank, no annualized cost is shown. Real delivered capacity is not a guarantee and should be checked against the manufacturer documentation.