How do you convert kWh to amp-hours?

Multiply kWh by 1,000 to get Wh, then divide by the battery voltage. The formula is Ah = (kWh x 1,000) / V. For example, 10 kWh at 48V: (10 x 1,000) / 48 = 208 Ah.

How many amp-hours do I need for 10 kWh of daily use?

At 48V: 208 Ah. At 24V: 417 Ah. At 12V: 833 Ah. These are the raw numbers before adjusting for depth of discharge. With lithium at 90% DoD, you need 231 Ah at 48V. With lead-acid at 50% DoD, you need 417 Ah at 48V.

How much battery capacity do I need for a whole house?

The average US home uses about 30 kWh per day. For one full day of backup at 48V with lithium (90% DoD): (30,000 / 48) / 0.90 = 694 Ah. That is roughly three Tesla Powerwalls (3 x 281 Ah). Most homeowners size for essential loads only (5-15 kWh/day), which requires 116-347 Ah at 48V with lithium.

Why is 48V better than 12V for large battery banks?

At 48V, the same energy requires one-quarter the amp-hours of a 12V system. Lower amps means thinner wires, smaller fuses, less voltage drop, and less energy lost as heat. A 10 kWh bank at 12V needs 833 Ah and massive cabling. At 48V it needs only 208 Ah with standard wiring.

How do I account for depth of discharge when converting kWh to Ah?

Divide the required Ah by the DoD percentage. For lithium LiFePO4 at 90% DoD, divide by 0.90. For lead-acid at 50% DoD, divide by 0.50. Example: 5 kWh at 48V = 104 Ah raw. With lithium DoD: 104 / 0.90 = 116 Ah. With lead-acid DoD: 104 / 0.50 = 208 Ah.

What is the average daily electricity use for a US home?

According to the EIA, the average US household uses about 10,500 kWh per year, which is roughly 29 kWh per day. However, this varies enormously by climate and home size: a small apartment in a mild climate might use 10-15 kWh/day, while a large home with electric heating in a cold climate can exceed 50 kWh/day.

How many 100Ah batteries do I need for 5 kWh?

At 12V, each 100Ah battery stores 1.2 kWh. You need 5 / 1.2 = 4.2, so five 12V 100Ah batteries (wired in parallel for 12V 500Ah = 6 kWh). At 48V, each 100Ah battery stores 4.8 kWh, so a single 48V 100Ah battery nearly covers it. Add DoD margin: with lithium at 90% DoD, you need 5 / (4.8 x 0.90) = 1.16, so two 48V 100Ah batteries gives comfortable headroom.

Should I use kWh or Ah when shopping for batteries?

Use kWh to compare total energy storage across different products regardless of voltage. Use Ah when you are designing a specific system at a known voltage and need to match components (charge controllers, fuses, wires). Modern home batteries are typically marketed in kWh. DIY components (individual cells, 12V/24V/48V batteries) are still commonly sold by Ah rating.

kWh To Amp-Hours Calculator (Convert Kilowatt-Hours To Ah)

Ah = (kWh x 1,000) / V. This conversion bridges the gap between your electricity bill (measured in kWh) and your battery bank (rated in Ah). If your home uses 10 kWh per day and you are building a 48V battery bank, you need at least 208 Ah of raw capacity -- and more after accounting for depth of discharge. This guide walks through the formula, provides a reference table for common daily usage levels, and shows how to properly size a battery bank with real-world adjustments.

Calculator

Battery voltage

Battery capacity

Battery chemistry

Target charge time

hrs

Required solar panel size

To charge a 100Ah 12V Lithium (LiFePO4) battery in 5 hours

Energy to charge

1.26kWh

If you use 100W panels

panels needed

If you use 200W panels

panels needed

171 kg

CO₂ avoided per year

0.04

equivalent US homes powered

trees planted equivalent

$74

estimated annual savings

Chemistry	Efficiency	Cycle Life	Panel Watts
Lithium (LiFePO4)	95%	3,000–5,000	252 W
Deep Cycle AGM	85%	500–1,000	283 W
Lead-Acid Flooded	80%	300–500	300 W

Tap to see sensitivity analysisSensitivity analysis

Sensitivity range
Scenario	Value
Low (-20%)	202 W
Expected	252 W
High (+20%)	302 W

Battery chemistry has the biggest effect \u2014 switching from lead-acid to lithium reduces required panel watts by ~20%.

What size battery do I need?See production for your state

The Formula: Ah = (kWh x 1,000) / V

Kilowatt-hours and amp-hours measure different things. Kilowatt-hours measure energy (how much total work can be done). Amp-hours measure charge capacity (how much current can flow over time at a given voltage). To convert between them, you need to know the system voltage.

Ah = (kWh x 1,000) / V

Where:

Ah = amp-hours
kWh = kilowatt-hours (multiply by 1,000 to convert to Wh)
V = nominal battery voltage

The "x 1,000" step converts kilowatt-hours to watt-hours (1 kWh = 1,000 Wh). From there, dividing by voltage gives amp-hours.

Why This Conversion Matters

Your electricity bill tells you how many kWh you use per month. Your solar installer or monitoring app tells you how many kWh your panels produce per day. But when you go to buy batteries, you see ratings like "100Ah 12V" or "200Ah 48V." To bridge this gap, you need to convert from the energy units on your bill to the capacity units on the battery label.

This conversion is especially critical for:

Off-grid system sizing: matching battery capacity to daily energy consumption
Backup power planning: determining how many batteries you need for a grid outage
Solar self-consumption: storing daytime solar production for nighttime use

kWh To Ah Conversion Table

Here are common daily energy consumption values converted to amp-hours at the three standard battery voltages:

Daily Usage (kWh)	At 12V	At 24V	At 48V	Typical Scenario
1 kWh	83 Ah	42 Ah	21 Ah	Small cabin, LED lights only
2 kWh	167 Ah	83 Ah	42 Ah	RV or boat essentials
3 kWh	250 Ah	125 Ah	63 Ah	Off-grid tiny house
5 kWh	417 Ah	208 Ah	104 Ah	Essential loads backup
10 kWh	833 Ah	417 Ah	208 Ah	Half-home backup
15 kWh	1,250 Ah	625 Ah	313 Ah	Moderate whole-home backup
20 kWh	1,667 Ah	833 Ah	417 Ah	Full whole-home backup
30 kWh	2,500 Ah	1,250 Ah	625 Ah	Average US home (full day)

These are raw capacity numbers before depth of discharge adjustments. Read the DoD section below before ordering batteries based on this table.

Worked Example: 10 kWh Daily Use

You use 10 kWh per day and want a 48V lithium battery bank to cover one full day without solar input.

Step 1 -- Convert kWh to Ah at your voltage:

Ah = (10 x 1,000) / 48 = 208 Ah

Step 2 -- Adjust for depth of discharge (90% for LiFePO4):

208 / 0.90 = 231 Ah

Step 3 -- Adjust for inverter efficiency (93%):

231 / 0.93 = 249 Ah

Step 4 -- Round up to available battery sizes:

You would need either three 48V 100Ah batteries (300 Ah total, giving comfortable headroom) or a single 48V 280Ah server-rack battery.

With lead-acid batteries at 50% DoD and the same 93% inverter efficiency:

208 / 0.50 / 0.93 = 447 Ah at 48V -- nearly double the lithium requirement.

Depth of Discharge: The Most Important Adjustment

The raw kWh-to-Ah conversion tells you the minimum capacity if you could drain the battery to zero. You cannot. Every battery chemistry has a recommended maximum depth of discharge:

Chemistry	Max DoD	Required Ah Multiplier	10 kWh at 48V (After DoD)
Lithium LiFePO4	80-100%	1.0-1.25x	208-260 Ah
AGM (sealed lead-acid)	50%	2.0x	417 Ah
Flooded lead-acid	50%	2.0x	417 Ah
Gel lead-acid	50%	2.0x	417 Ah

To apply the DoD adjustment, divide the raw Ah by the DoD fraction:

Adjusted Ah = Raw Ah / DoD

For 10 kWh at 48V with lithium at 90% DoD: 208 / 0.90 = 231 Ah minimum

For 10 kWh at 48V with lead-acid at 50% DoD: 208 / 0.50 = 417 Ah minimum

This is why lithium batteries, despite their higher upfront cost per Ah, often cost less per usable kWh. You need roughly half the total Ah capacity compared to lead-acid.

How To Find Your Daily kWh Usage

Before converting to Ah, you need to know how many kWh you actually use. Here are three methods:

Method 1 -- Check Your Electric Bill

Your monthly utility bill shows total kWh consumed. Divide by 30 to get daily average:

Daily kWh = Monthly kWh / 30

The average US household uses about 880 kWh per month, or roughly 29 kWh per day. But this varies enormously: a small apartment in San Diego might use 10 kWh/day, while a large home with electric heat in Minnesota can exceed 60 kWh/day in winter.

Method 2 -- Add Up Individual Loads

For backup power planning, list only the loads you want to run during an outage:

Load	Watts	Hours/Day	Daily Wh
Refrigerator	150W (avg)	24	3,600 Wh
LED lights (10 bulbs)	100W	6	600 Wh
WiFi router	12W	24	288 Wh
Phone chargers (2)	20W	4	80 Wh
Laptop	60W	6	360 Wh
Total			4,928 Wh (4.9 kWh)

This "essential loads" approach is how most people size backup battery systems. Running a full house including HVAC, water heater, and cooking appliances requires significantly more capacity.

Method 3 -- Energy Monitor

A whole-home energy monitor (like Sense or Emporia Vue) tracks real-time consumption by circuit. Install one for a week and you will have precise daily kWh data broken down by appliance.

Days of Autonomy

Off-grid systems need enough battery capacity to cover days with poor solar production (cloudy weather, storms, short winter days). The standard metric is days of autonomy -- how many days the batteries can power your loads without any solar input.

Total Ah = (Daily kWh x 1,000 x Days of Autonomy) / (V x DoD x Inverter Efficiency)

For 5 kWh/day with 3 days of autonomy on a 48V lithium system (90% DoD, 93% inverter):

Total Ah = (5 x 1,000 x 3) / (48 x 0.90 x 0.93) = 15,000 / 40.2 = 373 Ah

Most grid-tied backup systems plan for 1 day of autonomy (overnight use). Off-grid systems in cloudy climates typically plan for 3-5 days.

See our Days of Autonomy Calculator for a detailed walkthrough.

Choosing the Right System Voltage

Your choice of battery voltage determines how many amp-hours you need:

System Voltage	Best For	Typical Ah Range	Pros	Cons
12V	RVs, boats, small systems under 2 kWh	100-400 Ah	Simple, many products available	High current, thick wires, limited scalability
24V	Mid-size off-grid, 2-5 kWh systems	100-300 Ah	Moderate current, decent product selection	Less common than 12V or 48V
48V	Whole-home, 5+ kWh systems	100-400 Ah	Low current, thin wires, most efficient	Fewer budget options at this voltage

For any system above 3 kWh, 48V is strongly recommended. The lower current reduces wiring costs, improves efficiency, and makes the system safer. Nearly all modern home battery products (Tesla Powerwall, Enphase IQ, EG4, Sol-Ark compatible batteries) operate at 48V.