# Paint Calculator

> Free paint calculator. Enter your room dimensions and instantly find out how much paint you need, recommended can sizes, and estimated cost.

Canonical: https://renoquant.com/paint-calculator
Prices updated: 2026-03

## At a glance

Standard interior latex paint covers 10–12 m² per litre, and most walls need two coats. A typical 4×4 m room with 2.4 m ceilings (~38 m² of wall area after subtracting one door and one window) needs about 8 litres for two coats, costing roughly EUR 40–100 in materials. Coverage drops on rough or porous surfaces, and dramatic colour changes need a third coat.

## How to Calculate How Much Paint You Need

Calculating the right amount of paint for your room doesn't have to be guesswork. Our paint calculator uses a straightforward formula that professional painters rely on every day. If you are painting fresh plasterboard, use our [drywall calculator](/drywall-calculator) first to make sure the wall is ready for paint.

### The Paint Calculation Formula

The basic formula for calculating paint is:

**Paint needed = (Wall Area × Number of Coats) ÷ Coverage Rate + 10% Waste**

Where wall area is calculated as: **2 × (Room Length + Room Width) × Room Height**, minus the area of doors and windows.

### Step-by-Step Guide

1. **Measure your room** — Record the length, width, and height in meters (or feet).
2. **Count openings** — Note how many doors and windows are in the room.
3. **Choose your coats** — Most paint jobs require 2 coats for proper coverage.
4. **Enter the values** — Use our calculator above to get instant results.

### Understanding Paint Coverage

Paint coverage varies by type and quality:

| Paint Type | Coverage (m²/L) | Coverage (sq ft/gal) |
|-----------|----------------|---------------------|
| Standard Latex | 10-12 | 400-480 |
| Premium Latex | 12-14 | 480-560 |
| Primer | 8-10 | 320-400 |
| Ceiling Paint | 10-12 | 400-480 |

### Tips for Accurate Estimates

- **Textured walls** absorb more paint — increase your estimate by 15-20%.
- **Dark to light color changes** may need 3 coats or a tinted primer.
- **Always buy slightly more** than calculated — leftover paint is useful for touch-ups.
- **Check the can** — manufacturer coverage rates are printed on every paint can.
- **Prefer wallpaper instead?** Use our [wallpaper calculator](/wallpaper-calculator) to estimate rolls for a textured alternative to paint.

### Common Room Sizes and Paint Needed

| Room | Typical Size | Paint (2 coats) |
|------|-------------|----------------|
| Small Bedroom | 3×3×2.5m | ~4.5 L |
| Standard Bedroom | 4×5×2.5m | ~7.5 L |
| Living Room | 5×6×2.5m | ~10 L |
| Bathroom | 2×2.5×2.5m | ~3.5 L |

### Paint Types and When to Use Each

Different rooms and surfaces benefit from different paint formulations. Choosing correctly the first time saves repaints later.

| Paint Type | Best For | Coverage (m²/L) | Typical Price (€/L) | Drying Time |
|-----------|----------|-----------------|---------------------|-------------|
| Matte latex | Bedrooms, ceilings, low-traffic walls | 10-12 | 4-7 | 1-2 hr touch dry |
| Eggshell / satin latex | Hallways, living rooms (washable) | 10-12 | 5-8 | 2-3 hr |
| Semi-gloss / gloss | Trim, doors, skirting | 11-13 | 6-10 | 2-4 hr |
| Bathroom paint (anti-mould) | Bathrooms, utility rooms | 9-11 | 7-12 | 2-4 hr |
| Kitchen paint (washable) | Kitchen walls, splashbacks | 10-12 | 7-12 | 2-4 hr |
| Primer / undercoat | New plaster, dramatic colour change | 8-10 | 4-8 | 1-2 hr |
| Masonry / exterior | Render, brick, exterior walls | 6-8 | 5-9 | 4-6 hr |

Eggshell and satin sheens hide imperfections better than gloss but stay washable, which makes them the practical default for high-traffic interior walls.

### Surface Preparation Drives the Real Cost

Material costs are usually 30-40% of an interior repaint; the rest is labour, prep, and consumables. Prep effort almost always dominates the timeline:

| Surface Condition | Prep Steps | Extra Material |
|-------------------|-----------|----------------|
| Clean, previously painted, same colour | Wash + light sand | None |
| Previously painted, different colour | Wash + sand + 1 coat primer | +1L primer per ~10 m² |
| New plaster (mist coat needed) | Dilute first coat 30:70 with water | +20% paint volume |
| Filled holes or patches | Sand smooth + spot prime | Filler + small primer |
| Stained walls (smoke, water) | Stain-block primer | +1L stain block per 8-10 m² |
| Glossy old paint | Sand to dull or use de-glosser | Sandpaper or liquid sandblock |

Skipping these steps is the most common reason repaints fail within 2-3 years.

### Brush, Roller, or Sprayer?

Application method affects both speed and total paint volume.

| Method | Speed | Paint Used | Skill Needed | Best For |
|--------|-------|-----------|--------------|----------|
| Brush | Slow | Lowest waste | Easy | Trim, cutting in, small areas |
| Roller (9") | Fast | Standard | Easy | Walls, ceilings |
| Roller (4" mini) | Medium | Standard | Easy | Behind radiators, alcoves |
| Airless sprayer | Very fast | +20-30% overspray | Moderate | Whole rooms, fences, full repaints |
| HVLP sprayer | Medium | +10-15% | Moderate | Cabinets, doors, fine finishes |

For a single room, brush + roller is almost always cheaper than spraying once you factor in masking time and overspray loss.

### Common Mistakes to Avoid

- **Skipping the mist coat on new plaster** — Plaster sucks up paint unevenly; the first coat must be diluted 30% with water or it peels off later.
- **Painting in cold rooms** — Most latex paints need 10°C minimum to cure. Below that, the film stays soft for weeks and marks easily.
- **Reloading the brush mid-stroke** — Causes streaks. Finish the stroke, then reload.
- **Over-thinning to "stretch" the paint** — Reduces opacity and forces a third coat anyway.
- **Ignoring the manufacturer coverage rate** — Listed rates assume smooth, primed walls; rough plaster needs 15-25% more.

### When to Hire a Professional Painter

Consider hiring a professional if your project involves high ceilings, specialty finishes (texture, faux, or decorative painting), or multiple rooms. A professional painter can complete the job faster and with a more consistent finish. If you are also painting the outside of your house, check our [exterior paint calculator](/exterior-paint-calculator) for masonry and cladding estimates. Use our free quote tool below to connect with local painters.

## Frequently Asked Questions

### How accurate is the paint calculator?

Our calculator provides reliable estimates based on standard coverage rates. Actual coverage may vary depending on surface texture, paint quality, and application method. We add a 10% waste factor for safety.

### How many coats of paint do I need?

Most walls need 2 coats for even coverage. Use 1 coat for touch-ups over the same color, or 3 coats when covering a dramatically different color.

### Should I subtract doors and windows?

Yes. Our calculator automatically subtracts standard door (1.9 m²) and window (1.5 m²) areas from the total wall area for a more accurate estimate.

### What coverage rate should I use?

Standard interior latex paint covers about 10-12 m² per liter (400-480 sq ft per gallon). Premium paints may cover more. We default to 10 m²/L for a conservative estimate.

### How do I calculate paint for a ceiling?

For ceilings, simply multiply room length by room width. Our calculator focuses on wall paint, but you can use the same formula: ceiling area ÷ coverage rate × number of coats.

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Interactive version with calculator: https://renoquant.com/paint-calculator. Figures are estimates; final quotes vary by site conditions, materials, and region.