Cost per watt-hour ($/Wh) is how you compare battery deals on equal energy—not amp-hours alone. This guide shows how to calculate battery cost per watt-hour from listings, then use Ah, voltage, and $/Wh in the estimator for total pack price.
Benefits
- Formula: $/Wh = pack price ÷ rated Wh (Ah × V).
- Forward check: total cost = Wh × $/Wh in the interactive tool.
- Benchmark LiFePO4, AGM, and NMC quotes on one unit-price line.
How it works
- Compute rated Wh = amp-hours × nominal voltage from the spec label.
- Divide sticker or quote price by Wh to get cost per watt-hour.
- Enter that $/Wh with Ah and V in the calculator to verify total pack cost.
FAQ
How do I calculate battery cost per watt-hour?
$/Wh = pack price ÷ rated Wh. Rated Wh = Ah × V. Example: $420 for 100 Ah × 12 V → 1,200 Wh → $420 ÷ 1,200 = $0.35/Wh. Use that $/Wh to compare other packs or multiply by any target Wh for budget estimates.
What is a typical $/Wh for home storage batteries?
Complete LiFePO4 packs often run $0.10–$0.25/Wh retail; AGM may look similar upfront but higher cycle cost. Premium branded rack batteries can exceed $0.30/Wh. Always divide quoted price by nameplate Wh—marketing Ah at one voltage can hide expensive $/Wh.
Should I use nominal or usable Wh for $/Wh?
Use nameplate rated Wh for comparing vendor quotes apples-to-apples. For bank sizing, apply depth-of-discharge—usable Wh may be 80–90% of rated for LiFePO4. Cost per usable Wh = price ÷ (rated Wh × DoD) when modeling runtime budgets.
Technical specifications
- Rated Wh = Ah × V.
- $/Wh = pack_price ÷ rated_Wh.
- Pack cost $ = rated_Wh × $/Wh.
- Related: battery-pack-cost-calculator, ah-to-wh, wh-to-ah.
Divide price by energy, not by Ah
A 200 Ah 12 V listing sounds bigger than 100 Ah 24 V—but both are 2,400 Wh. Cost per watt-hour exposes which sticker is cheaper per unit of stored energy. Retail shoppers who only sort by Ah often overpay for voltage they do not need or underbuy energy they do.
Build a $/Wh table from three quotes
For each candidate: Wh = Ah × V, then $/Wh = price ÷ Wh. Sort ascending. The winner on $/Wh may still lose on form factor, warranty, or shipping— but you start from comparable economics. Enter the best $/Wh into the calculator with your target bank Ah and V to project total install cost.
From $/Wh to project budget
Planning 10 kWh (10,000 Wh) at $0.16/Wh implies ~$1,600 in cells before BMS, cables, and labor. Multiplying Wh × $/Wh scales a unit price learned from one pack to a whole bank. Reverse the math on a vendor quote to see if their $/Wh beats your spreadsheet benchmark.