What Size Inverter & Battery Do I Need? (India 2026)
Sizing an inverter has two separate parts: the VA rating decides how much you can run at once, and the battery Ah decides how long it lasts. Get either wrong and you either trip on overload or run out of backup early. Below is the load-to-VA and backup-hours-to-Ah working Indian buyers actually need, the common home combo, and what should never go on a home inverter. When you are ready to buy, see our best inverter & battery guides. Backing up a whole home that also runs an AC? First size the AC with our what size AC do I need guide — it will not run on this inverter.
Inverter & battery size by household load
| Load you want to back up | Typical home | Inverter | Battery |
|---|---|---|---|
| Up to ~300 W (a few fans + LED lights) | 1 BHK / small flat, basic backup | 600 VA | 100 – 150 Ah (1 battery) |
| ~300 – 500 W (fans, lights, TV, router) | Standard 2 BHK family home | 800 VA – 1 kVA | 150 Ah tall tubular (1) |
| ~500 – 800 W (add a fridge, more fans) | Larger 2–3 BHK, longer backup | 1 kVA – 1.1 kVA | 150 – 200 Ah (1) |
| ~800 – 1500 W (whole-home essentials) | 3–4 BHK / bungalow | 1.5 kVA (24 V) | 2 × 150 Ah (24 V bank) |
| ~1500 – 2500 W (heavy essentials) | Large home, many rooms | 2 – 2.5 kVA (24–48 V) | 2–4 × 150 Ah bank |
Assumes fans, LED lights, TV, router and chargers only — no AC, geyser or pump. VA comes from watts ÷ power factor (~0.7–0.8) with headroom; battery Ah comes from your backup hours. These are standard rule-of-thumb formulas — your actual list of appliances is what matters.
Size up (more VA or Ah) if…
- You want longer backup — more backup hours means more battery Ah, not a bigger inverter VA.
- You plan to add appliances later (a fridge, another TV, more fans) — size with ~20–30% headroom now.
- You run motor-based loads with a high starting surge (a small pump, a mixer) — they briefly draw far more than their rated watts.
- Your home has frequent, long power cuts — a taller-tubular, higher-Ah battery lasts the outage better.
- You are using a 24 V or 48 V system — the battery Ah maths uses that higher pack voltage, not 12 V.
- You want to run it off solar later — plan the inverter and battery bank around that from the start.
How to size your inverter & battery — step by step
- Add up the load in watts. List only what you must run during a cut and add their wattages — e.g. 3 fans (~225 W) + 4 LED lights (~40 W) + 1 TV (~100 W) ≈ 365 W. Leave out the AC, geyser and motors.
- Convert watts to inverter VA. Divide total watts by the power factor (~0.7–0.8). So ~365 W ÷ 0.7 ≈ 520 VA. That is the minimum VA the inverter must supply.
- Round up to a standard size with headroom. Pick the next standard rating above your number and keep ~20–30% spare — for a ~520 VA need, choose an 800 VA (or 1 kVA) inverter, not a bare 600 VA maxed out.
- Size the battery Ah for your backup hours. Battery Ah ≈ (load watts × backup hours) ÷ (battery voltage 12 V × efficiency ~0.8). For 365 W for 3 hours: (365 × 3) ÷ (12 × 0.8) ≈ 114 Ah — so a 150 Ah tubular battery.
- Match the battery to your outage length. A tall-tubular battery suits long, frequent Indian power cuts and deep cycling; more Ah (or more batteries in a bank) buys more hours. The most common home combo is an 800 VA–1 kVA sine-wave inverter with a 150 Ah tall-tubular battery.
- Never put an AC, geyser or big motor on it. A normal home inverter is built for fans, lights, TV, router and chargers. Air conditioners, geysers, water pumps and other heavy motor/heating loads draw far more than a home inverter can supply — size those on a separate, dedicated system.
Frequently asked questions
What size inverter do I need for a home in India?
Add up the watts you want to run during a power cut — a typical 2 BHK running a few fans, LED lights, a TV and a router draws roughly 300–500 W. Divide by a power factor of about 0.7–0.8 to get VA (say ~365 W ÷ 0.7 ≈ 520 VA), then round up to the next standard size with 20–30% headroom. For most Indian homes that lands on an 800 VA to 1 kVA sine-wave inverter.
Is a 150Ah battery enough for a home inverter?
For most Indian homes, yes. A 150 Ah tall-tubular battery paired with an 800 VA–1 kVA inverter is the common home combo and comfortably backs up fans, lights, a TV and a router for a few hours. Using the standard formula, a ~365 W load for 3 hours needs (365 × 3) ÷ (12 × 0.8) ≈ 114 Ah — which a 150 Ah battery covers with margin. For longer backup or a heavier load, step up the Ah or add a second battery.
How do I calculate inverter VA from watts?
Divide your total load in watts by the power factor, which for a home inverter is about 0.7–0.8. For example, a 365 W load ÷ 0.7 ≈ 520 VA. That is the minimum the inverter must deliver, so you then round up to the next standard rating (600 VA, 800 VA, 1 kVA) and keep some spare capacity. Never run the inverter at its exact maximum.
What size inverter do I need to run a fridge?
A fridge is a motor load with a starting surge, so include its running watts in your total and keep extra headroom for the start-up spike. In practice, adding a fridge pushes a typical home from an 800 VA up to around a 1 kVA to 1.1 kVA sine-wave inverter, paired with a 150–200 Ah battery for reasonable backup. Always use a pure sine-wave inverter for a fridge, not a square-wave one.
Can I run an AC on a normal home inverter?
No. A regular home inverter and battery are meant for fans, lights, a TV, a router and chargers — not for air conditioners, geysers, water pumps or other heavy motor and heating loads, which draw far more power than a home inverter can supply. Running an AC needs a much larger, dedicated inverter or generator system; do not size your normal home backup around it.
How many hours will an inverter battery last?
Backup hours depend on your load and battery size, not just the inverter. Rearranging the standard formula, backup hours ≈ (battery Ah × 12 V × 0.8) ÷ load watts. A 150 Ah battery on a ~365 W load gives roughly (150 × 12 × 0.8) ÷ 365 ≈ 4 hours; the heavier the load, the fewer the hours. Want longer backup? Add battery Ah, not inverter VA.
What is the difference between inverter VA and battery Ah?
They size two different things. Inverter VA is about power — how much load (how many watts of fans, lights and TV) you can run at once, set by dividing watts by the power factor. Battery Ah is about energy — how long that load runs before the battery drains, set by your desired backup hours. You pick the VA from your peak load and the Ah from how many hours of backup you want.
PakkaPick researches appliance value for Indian buyers. Inverter and battery sizing here uses standard rule-of-thumb formulas (watts ÷ power factor for VA, and backup hours for Ah) and is guidance, not a substitute for advice from a qualified electrician for your specific load and wiring. As an Amazon Associate, PakkaPick earns from qualifying purchases.