# What size inverter and battery do I need? Simple guide for India

> Add the watts you need during a power cut, divide by 0.8 for inverter VA, then size the battery for backup hours. Worked 1BHK–3BHK examples, tubular vs lithium, prices and care.

- URL: https://2search.in/knowledge/articles/oct-26/inverter-battery-size-guide-india
- Genre: Energy savings
- Country: India
- Published: 2026-10-27
- Updated: 2026-10-27
- Publisher: 2search (https://2search.in)

> **Quick answer:** Add up the **watts** of everything you want to run during a power cut, then **divide by 0.8** to get the inverter size in **VA** — for example, 600 W ÷ 0.8 = **750 VA** (buy the next size up, like 900–1100 VA). For the battery: **backup hours ≈ (battery Ah × battery volts × ~0.8) ÷ load in watts**. A **12 V 150 Ah** battery running **300 W** lasts about **4–5 hours**. Choose a **pure sine wave** inverter and a **tubular** battery for most homes, or **lithium (LFP)** for long life and zero maintenance.

> **Key takeaways**
> - **Inverter VA** decides *how much* you can run; **battery Ah** decides *for how long*.
> - Use **BLDC fans and LED lights** to double your backup time for little money.
> - **Tubular** batteries cost about **₹12,000–₹18,000** (150 Ah) and last **4–6 years** with care; **lithium** costs **3–4×** more but lasts **10+ years**.
> - Don't run **ACs, geysers, irons or induction cooktops** on a normal home inverter.
> - **Pure sine wave** output protects fans, fridges and electronics and keeps fans quiet.

Power cuts are still common in many parts of India, especially in summer. A properly sized inverter keeps fans, lights, Wi-Fi and the TV running without wasting money on a bigger system than you need. This guide walks through the simple maths, gives ready-made sizes for typical homes, and helps you choose the right battery.



![What size inverter and battery do I need? Simple guide for India Breakdown & Visual Guide](/images/articles/inverter-battery-size-guide-india/diagram.svg)

## Step 1: List what you want to run

| Appliance | Typical watts |
| --- | --- |
| LED bulb | 9–12 W |
| LED tube light | 18–22 W |
| Ceiling fan (regular) | 60–75 W |
| **BLDC ceiling fan** | **28–35 W** |
| Table / pedestal fan | 40–55 W |
| Wi-Fi router + ONT | 10–20 W |
| LED TV (32–43") | 40–100 W |
| Set-top box | 10–20 W |
| Laptop charger | 45–90 W |
| Desktop PC + monitor | 150–300 W |
| Mobile charger | 5–20 W |
| Refrigerator (running; starting surge is higher) | 100–250 W |
| Water purifier (RO) | 25–60 W |
| Mixer grinder (short use) | 500–750 W |

**Avoid on a normal inverter:** AC (1,000–2,000 W+), geyser (2,000 W), iron (1,000 W), induction cooktop (1,500–2,000 W), microwave (1,000–1,500 W), washing machine heaters.

## Step 2: Work out the inverter size (VA)

**Inverter VA = total watts ÷ 0.8** (0.8 is the power factor for typical home loads). Then pick the **next standard size up** for safety and future additions.

> **Example:** 4 BLDC fans (4 × 32 W = 128 W) + 6 LED bulbs (6 × 10 W = 60 W) + 2 LED tubes (40 W) + Wi-Fi (15 W) + TV (70 W) + laptop (60 W) = **373 W**.
> 373 ÷ 0.8 = **466 VA** → choose a **700–900 VA** inverter.

Standard home inverter sizes: **600–700 VA, 850–900 VA, 1100 VA, 1500 VA, 2000–2500 VA** (bigger ones usually use 24 V with two batteries).

## Step 3: Work out the battery size (Ah) for your backup hours

**Backup hours ≈ (Ah × battery voltage × 0.8) ÷ load in watts**

The 0.8 allows for inverter losses and avoids draining the battery completely.

| Battery | Load 200 W | Load 300 W | Load 500 W |
| --- | --- | --- | --- |
| 12 V 100 Ah | ~4.8 h | ~3.2 h | ~1.9 h |
| 12 V 150 Ah | ~7.2 h | ~4.8 h | ~2.9 h |
| 12 V 200 Ah | ~9.6 h | ~6.4 h | ~3.8 h |
| 2 × 12 V 150 Ah (24 V system) | ~14.4 h | ~9.6 h | ~5.8 h |

These are estimates. Real backup is a bit lower with older batteries, high temperatures and fridges that cycle on and off.

To find the **battery you need**: **Ah = (load W × hours) ÷ (12 × 0.8)** for a 12 V battery.

> **Example:** 373 W for 4 hours → (373 × 4) ÷ 9.6 = **155 Ah** → a **12 V 150–165 Ah** battery.

## Ready-made sizes for typical homes

| Home | What you run | Inverter | Battery | Expected backup |
| --- | --- | --- | --- | --- |
| **1BHK** | 2 fans, 4 lights, Wi-Fi, TV | 700–900 VA | 1 × 12 V 150 Ah | ~4–6 h |
| **2BHK** | 3–4 fans, 6–8 lights, Wi-Fi, TV, laptop | 900–1100 VA | 1 × 12 V 150–200 Ah | ~3–5 h |
| **2BHK with fridge** | Above + fridge | 1100–1500 VA | 2 × 12 V 150 Ah (24 V) | ~5–7 h |
| **3BHK** | 5–6 fans, 10 lights, 2 TVs, Wi-Fi, PC | 1500–2000 VA | 2 × 12 V 150–200 Ah (24 V) | ~4–6 h |

> **Tip:** Replacing **regular fans with BLDC fans** cuts each fan's load from ~70 W to ~30 W. In a 4-fan home, that's 160 W saved — often enough to **double** your backup time on the same battery.

## Tubular vs flat plate vs lithium batteries

| | **Flat plate** | **Tall tubular** | **Lithium (LFP)** |
| --- | --- | --- | --- |
| Price (150 Ah equivalent) | Lowest | ~₹12,000–₹18,000 | ~₹40,000+ |
| Typical life | 2–4 years | **4–6 years** | **10+ years** (3,000+ cycles) |
| Best for | Short, rare power cuts | **Frequent, long cuts** — most homes | Daily long cuts, solar, apartments |
| Maintenance | Water top-up every 1–2 months | Water top-up every 3–6 months | **None** |
| Charging speed | Slow | Slow–medium | **Fast** |
| Usable capacity | ~50–60% | ~70–80% | **80–90%** |
| Weight / space | Heavy | Heavy, tall | Light, compact |
| Fumes | Some during charging | Some | None |

**Lithium** works best with an inverter designed or configured for lithium charging. Ask the seller to confirm compatibility.

## Pure sine wave vs square wave inverters

- **Pure sine wave:** clean power like the grid — fans run **quiet and cool**, and fridges, laptops, LED drivers and pumps are safe. **Choose this.**
- **Square / modified sine wave:** cheaper, but causes **humming in fans**, more heat, and can damage sensitive electronics.

## Solar-ready and hybrid options

If you plan rooftop solar later:

- A **solar inverter (PCU)** or **hybrid inverter** can charge the battery from solar panels during the day.
- **On-grid solar** under the PM Surya Ghar subsidy doesn't provide backup by itself — see [PM Surya Ghar subsidy](/pm-surya-ghar-rooftop-solar-subsidy).
- **Hybrid systems** combine both: grid export plus battery backup.

## Battery care: make it last

- **Top up with distilled water** only, up to the max mark (lead-acid). Check every 1–3 months in summer.
- Keep the battery in a **ventilated, shaded** spot — never in a closed cupboard or direct sun.
- Keep **terminals clean** and apply petroleum jelly to prevent corrosion.
- **Don't drain it fully** often; recharge soon after long cuts.
- If you have few power cuts, **discharge it once a month** to keep it healthy.
- Don't add **new loads** like an iron or heater "just for a minute".

## Installation and safety

- Use proper **wiring through the inverter circuit** (only selected sockets and lights).
- Use **thick enough cables** between inverter and battery, with secure lugs.
- Keep children away from batteries; lead-acid batteries contain **acid** and release **hydrogen** while charging.
- Use a **stand** or tray for batteries, not the bare floor.

## Buying checklist

1. ☐ Your **load in watts** and needed **backup hours**
2. ☐ **Pure sine wave** inverter, right VA size
3. ☐ **Tall tubular** (or lithium) battery with the right Ah
4. ☐ Warranty: inverter **2–3 years**, tubular battery **36–60 months** (part free + pro-rata)
5. ☐ Battery **trolley/stand** and installation included
6. ☐ **Bypass switch** and overload protection
7. ☐ **Solar-ready** if you may add panels later

## Frequently asked questions

### Which inverter is best for a 2BHK flat?

Usually a 900–1100 VA pure sine wave inverter with a 150–200 Ah tubular battery, for fans, lights, Wi-Fi and a TV.

### How long will a 150 Ah battery last?

About 4–5 hours at 300 W, 7 hours at 200 W, and under 3 hours at 500 W.

### Can I run a fridge on an inverter?

Yes, on a pure sine wave inverter of about 1100 VA or more. Fridges draw a surge when starting, so size up.

### Can an inverter run an AC?

Not a normal home inverter. ACs need large inverters, big battery banks or solar hybrid systems.

### Is lithium better than tubular for home inverters?

Lithium lasts longer and needs no maintenance, but costs several times more. Tubular is still the best value for most homes.

### How do I calculate inverter VA?

Add up the watts you'll run and divide by 0.8, then choose the next standard size.

### How often should I add water to an inverter battery?

Check every 1–3 months, especially in summer. Use only distilled water.

## Sources

- [Bureau of Energy Efficiency — Standards & labelling (appliance energy use)](https://beeindia.gov.in/)
- [Bridgeway Power — Lithium-ion vs lead-acid battery in India](https://bridgewaypower.in/blog/lithium-ion-vs-lead-acid-battery-india)
- [Bajaj Finserv — Top inverter batteries in India (2026)](https://www.bajajfinserv.in/top-10-inverter-battery-in-india)
- [Kunwer Sachdev — Lithium vs tubular battery for inverter](https://kunwersachdev.com/the-ultimate-guide-lithium-battery-vs-tubular-battery-for-inverter/)