# Home renovation calculator for Mac, Windows and Linux

Written on 25 October 2026 by Ratio.

Measure once, then type the room: Ratio turns square metres into litres, bags and boxes, and keeps the units so you can check them.

## Materials

| 3 m * 4 m | 12 m² |
| --- | --- |
| paint 40 m2 2 coats | 8 L |
| paint 40 m2 2 coats at 12 m2/l | 6.7 L |
| tiles 12 m2 | 13.2 m² |
| tiles 12 m2 + 15% | 13.8 m² |
| concrete 2 m3 | 184 |
| 20 m2 in sq ft | 215.28 ft² |

Paint covers 10 m² a litre unless you say otherwise; tiles get 10% for cuts and breakage; concrete counts 25 kg bags of ready mix (“concrete 2 m3 in 40 kg bags”).

## Buying and renting

| mortgage 300k with 20% down at 5% for 30 years | 1,288.3719 |
| --- | --- |
| loan 240k at 5% for 30 years | 1,288.3719 |
| rental yield 1200/month on 250k | 5.76% |

[Try Ratio free for 7 days](https://useratio.app/download) · $14.99 once, updates included

## Questions

**How much paint do I need?** Area × coats ÷ coverage: “paint 40 m2 2 coats” gives 8 litres at 10 m² a litre. Add “at 12 m2/l” for the coverage on your tin.

**How many bags of concrete for a cubic metre?** About 92 bags of 25 kg, counting 2,300 kg of dry mix per m³. Check the bag: yields vary by brand.

**Can it include the down payment?** Yes: “mortgage 300k with 20% down at 5% for 30 years” borrows 240k. A fixed amount works too: “with 60k down”.

Source: https://useratio.app/home-renovation-calculator