How big should my shade structure be?

As a rule, the shade structure should be at least as large as the area you want to shade at midday. Account for the sun moving throughout the day, as morning and afternoon shadows will fall at different angles.

What height should a pergola be?

Minimum 2.2m clearance for walking beneath. Taller structures (2.5-3m) create a more open feel but require larger coverage area since high structures cast shadows further from the structure.

Do shade sails provide full shade?

Shade sails typically block 80-95% of UV depending on the fabric. They provide excellent coverage but the shade moves with the sun. Overlapping sails can provide more complete coverage.

How does latitude affect shade planning?

In the UK (50-58° latitude), the summer sun reaches about 60° at its highest. Further north, the sun is lower and shadows are longer. This affects the size and positioning of shade structures.

Which orientation is best for shade?

South-facing structures get the most intense midday sun and benefit most from shade. East-facing areas need morning shade; west-facing need afternoon shade. North-facing areas rarely need shade structures.

GardenCalcs

Shade Coverage Calculator — Shade Structure Sizing

Calculate shade structure size and positioning for garden areas.

Area to Shade

Area to shade in m²

Latitude

UK: 50-58°. London ~51.5°, Edinburgh ~56°

OrientationOrientation

Structure TypeStructure type

Time to ShadeTime to shade

How We Calculate This

The calculator works out the shade structure size needed based on the area to shade, the sun angle at your latitude, and the efficiency of your chosen structure type.

Sun angle: Estimated as 90° - latitude + 23.5° (summer solstice maximum). This determines shadow length and coverage.

Structure efficiency: Pergolas ~65% (gaps between slats), Shade sails ~85%, Umbrellas ~90%, Trees ~70% (variable canopy density). The required structure size is adjusted by efficiency.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.