Water Heater Size Calculator
Estimate the storage tank size a household needs from occupants and daily hot water use.
Compare Your Options And Get Clear Answers
Estimate the storage tank size a household needs from occupants and daily hot water use.
Water Heater Size Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Results update as you change the inputs.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Water Quick Guide
Typical values for reference.
| People | L/person | Bathrooms | Tank |
|---|---|---|---|
| 1 | 45 | 1 | 60 litres |
| 2 | 45 | 1 | 100 litres |
| 4 | 45 | 2 | 200 litres |
| 6 | 45 | 3 | 290 litres |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Water Heater Size Calculator FAQ
Answers to common questions about this calculator.
Many homes use 100 to 250 litres, depending on people and bathrooms.
No. Oversized tanks lose more heat and cost more to run.
Tank = people x litres per person x reserve factor x 0.7 + 20 L per bathroom.
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.