Window Size to Room Ratio Calculator
Check whether your window area gives enough daylight compared with the room floor area.
Compare Your Options And Get Clear Answers
Check whether your window area gives enough daylight compared with the room floor area.
Window Size to Room Ratio 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.
Window Quick Guide
Typical values for reference.
| Floor m2 | Window m2 | Orientation | Ratio % |
|---|---|---|---|
| 18 | 1.5 | 1 | 8.3% |
| 18 | 3.2 | 1 | 17.8% |
| 18 | 4.5 | 1 | 25.0% |
| 18 | 6 | 1 | 33.3% |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Window Size to Calculator FAQ
Answers to common questions about this calculator.
About 15 to 20 percent for good daylight.
Yes, south-facing rooms get more light in the northern hemisphere.
Ratio = window area / floor area x 100.
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.