Every wall, every side

Exterior paint calculator

Plan exterior paint from the surfaces you will coat. Add wall faces and gables, subtract unpainted openings, and round the estimate to whole containers.

METRIC + US UNITS

Plan the outside.

YOUR BUILDING

Measurement system

Metric (m, litres) US (ft, gallons)

Rectangular exterior walls

Measure wall width and height to the eaves. Add every face you plan to paint; split irregular surfaces into non-overlapping sections.

Triangular gables (optional)

Each triangle is base × vertical height ÷ 2. Height is from the eaves to the peak, not the sloping roof length. Don’t count a gable again in the rectangles.

Doors & windows to subtract

Enter each rectangular opening you won’t paint. Remove all rows if you prefer not to subtract openings. Up to 30 rows in each section.

Number of coats

Coverage (m²/L)Per coat. Use your exterior paint’s label.

Extra allowance (%)Adjust for surface texture and application losses.

Container size (L)Rounds up whole containers of this one size.

Switching units converts dimensions, label coverage, and container size. Gallons mean US gallons. Check your actual paint and container size before buying.

Your exterior paint plan

ESTIMATED

Calculate a plan

The example will calculate when JavaScript is enabled.

Rectangular wall area—

Triangular gable area—

Total exterior surface area—

Doors & windows subtracted—

Area to paint per coat—

Coats / coverage per coat—

Paint before extra allowance—

Paint including extra allowance—

Planning estimate only. Product, texture, porosity, condition, and application method affect coverage. Roofs, soffits, trim, doors being painted, primer, and other products need separate estimates.

Results reflect the last successful calculation. Recalculate after editing inputs.

Calculated with TinkerMint · An estimate based on the inputs shown.

How to estimate exterior paint

Choose metric or US units. Enter each rectangular wall’s width and height to the eaves, using measurements you can obtain safely.
Add gables using the base width and vertical height above the eaves. Remove any unused gable rows.
Enter doors and windows that will not receive this paint. Remove all opening rows if you prefer not to subtract them.
Set coats, coverage per coat, extra allowance, and container size from your project and product label. Choose Plan my exterior paint after editing.

Start with the surface.

A building’s footprint does not give its exterior wall area. Add the width × height of all wall faces to be painted, then add any gables as triangles. Subtract windows and doors that won’t receive the same paint.

The label coverage and 10% allowance shown are illustrative. Rough, porous, or weathered surfaces can need a different allowance or preparation. Check the product instructions, and estimate each paint or primer separately.

Use plans or measurements you can obtain safely. Do not climb onto a roof or work at height to use this calculator; ask a qualified professional when needed.

How the exterior adds up.

Net area = rectangular walls + triangular gables − openings. Multiply by coats, divide by coverage per coat, add the extra allowance, then round up to whole containers.

The default exampleThe default has two 10 m × 3 m walls and two 8 m × 3 m walls (108 m²), plus two gables with an 8 m base and 2 m vertical height (16 m²). Subtract one 1 m × 2 m door and two 1.5 m × 1.2 m windows (5.6 m²). The 118.4 m² net area, 2 coats at 10 m²/L, and 10% extra require 26.048 L: 11 containers of 2.5 L, or 27.5 L total.

One foot = 0.3048 metres. One US gallon = 3.785411784 litres. Neither floor area nor sloping roof area is used as a substitute for wall area.

A few things worth checking.

Can I use the building’s floor area?

Measure the exterior wall faces instead. Floor area does not capture wall height, perimeter, or gables, and sloping roof length is not the vertical height of a gable.

Does this include primer or trim paint?

Calculate each product separately using its own surfaces, coat count, and label coverage. The estimate does not choose a primer, inspect the surface, or account for every application loss.