Geyser Size Calculator
Tell us how you bathe and how many people use hot water back-to-back. Get the right storage litres or instant kW, plus the warm water it delivers and indicative running energy. Because hot water mixes with cold, a 15 L geyser gives far more than 15 L of usable warm water. Indicative India 2026.
Your hot-water use
We assume ~35 L of warm water per person for a shower. Stored water at ~60°C is mixed down to a ~40°C bath, so each stored litre stretches further — more so with warmer inlet water. Confirm the model and warranty locally.
Typical sizing at a glance
1 bucket bath
3 L · 3 kW instant
Single tap, quick warm-up
1 shower
10-15 L storage
One person, comfortable
Couple, back-to-back
15-25 L storage
Two showers in a row
Family of 4
25 L storage
Reheats between users
Bathtub / luxury
35-50 L storage
Large draw in one go
Recommended storage capacity
0 L
delivers about 0 L of warm water per full heat-up
Warm water needed
70 L
~35 L/person
Hot @60°C
39 L
56% hot in the mix
Storage size
50 L
alt: 4.5 kW instant
Energy / session
2 kWh
≈ ₹16 at ₹8/unit
Hot-water demand (litres at 60°C) by scenario. Your current setup is highlighted when it matches. Indicative — confirm locally.
A 5-star BEE storage geyser loses less standing heat than a 3-star one — worth it if the geyser stays on. Instant models draw 3-4.5 kW while running, so check your wiring and MCB. One full tank heat-up here is ≈ 2.6 kWh.
Pick the right geyser & spot
Get model, BEE-star and placement advice for your bathroom from DesignAI.
Go deeper
Estimates are indicative and assume ~40°C bathing water from a ~60°C tank. Real hot-water need varies with habits, pipe runs, ambient temperature and geyser efficiency. Confirm the exact capacity, BEE-star rating, wattage and electrical load with your plumber and electrician before buying — and never oversize a storage geyser you leave switched on.
Frequently asked questions
- How does the geyser size calculator decide the litres or kW I need?
- It estimates the warm water each person uses per bath by usage type, then converts that to litres of stored 60°C water using how much hot water is in a roughly 40°C comfort mix. Because stored hot water is diluted with cold, one stored litre stretches further, so a 15 litre tank delivers far more than 15 litres of usable warm water. It then snaps the result to a standard tank size or an instant kW band.
- What inputs should I enter and what are sensible defaults?
- Pick how you bathe (bucket, shower or both), how many people use hot water back-to-back, whether a bathtub is fed, storage or instant type, and your inlet water temperature. Use winter cold, around 15°C, for the toughest case in most of India; moderate is around 25°C. A couple taking back-to-back showers in winter is a good starting point if you are unsure.
- Should I choose a storage geyser or an instant one?
- Instant geysers heat water only as it flows and draw 3 to 4.5 kW, so they suit a single tap or one quick bucket bath and need adequate wiring and MCB. Storage tanks hold a heated reserve and handle several back-to-back showers, a family, or a bathtub far better. For most Indian bathrooms with more than one user a 15 to 25 litre storage tank is the practical choice.
Related Guides — Deep-dive reading
Geyser for Bathroom India: Water Heater Types, Sizing, Star Rating & Safe Wiring (2026)
How to choose a bathroom water heater in India — storage vs instant vs gas vs solar, the right litres for a bucket bath or shower, BEE star rating and running cost, why hard water needs an anode and descaling, pressure rating for showers, and the dedicated electrical point and safety it must have.
BathroomsHow to Choose a Geyser in India: Buyer's Guide to Size, Type, Star Rating & Price (2026)
A buyer's decision guide to picking a bathroom geyser in India — sizing instant vs storage by family and use, storage vs instant vs gas vs solar, BEE star rating and running-cost maths, glass-lined vs stainless tank for hard water, pressure rating, warranty, good-better-best price tiers, the IS 302 safety mark, and how to spot a refurbished unit.
BathroomsHot Water Systems Guide (India): How to Choose the Right Water Heater
Electric, gas, solar or heat-pump? Central or point-of-use? A homeowner's how-to-choose overview that compares every water-heating option on upfront cost, running cost and where each one actually suits an Indian home.
PlumbingRelated Tools — You may also find these useful
Bathtub Size Calculator
Bathtub water volume, the hot water and geyser size a bath needs, fill time and a room-fit check — by tub type and size.
Bathroom CalculatorGeyser Running Cost Calculator
Work out a water heater's electricity use and running cost per day, month and year — and compare electric, gas, heat-pump and solar.
Bathroom CalculatorHeated Towel Rail Calculator
Size an electric heated towel rail (wattage and bars) and work out its running cost per month and year at your tariff.
Bathroom Calculator