How many hours of direct sun does my garden get?
Full sun, partial shade or shade: hours behind fences and walls of different heights, by season.
Reading the tables
Hours from solar noon, metres per metre
The hours are counted from solar noon, when the sun is highest, because the shadow is symmetrical around it: the afternoon has the same lengths as the morning. Multiply a figure by the height of the object to get its shadow.
Solar noon in London falls at about 13:02 on the clock in late June, 12:07 in March and 11:58 in December; in Madrid at about 14:16, 13:22 and 13:12. A dash means the sun is below the horizon or right on it.
London, 51.5° N
Shadow length in London
| Date | Noon | 1 h | 2 h | 3 h | 4 h | 5 h | 6 h |
|---|---|---|---|---|---|---|---|
| 21 June | 0.53 m | 0.59 m | 0.73 m | 0.98 m | 1.34 m | 1.93 m | 3.05 m |
| 20 March | 1.26 m | 1.33 m | 1.57 m | 2.05 m | 3.07 m | 6.2 m | — |
| 21 December | 3.72 m | 4.04 m | 5.36 m | 11 m | — | — | — |
In London a summer shadow stays shorter than the object itself for three hours either side of noon; in December the shortest shadow of the day is 3.7 times the object’s height.
Madrid, 40.4° N
Shadow length in Madrid
| Date | Noon | 1 h | 2 h | 3 h | 4 h | 5 h | 6 h |
|---|---|---|---|---|---|---|---|
| 21 June | 0.31 m | 0.39 m | 0.59 m | 0.88 m | 1.31 m | 2.05 m | 3.74 m |
| 20 March | 0.85 m | 0.92 m | 1.14 m | 1.57 m | 2.44 m | 5.0 m | — |
| 21 December | 2.04 m | 2.18 m | 2.70 m | 4.11 m | 11 m | — | — |
Eleven degrees of latitude make a large difference in winter: at noon on the shortest day a London shadow is 3.7 times the object’s height and a Madrid one twice the height.
Rules of thumb
What the tables say
- When the sun is 45° high a shadow is exactly as long as the object. In London in June that is the case from about three hours before solar noon to three hours after it; in December the sun never gets that high.
- Near sunrise and sunset shadows run away: in the last hour before sunset a shadow can grow from two or three times the height to ten times or more.
- In London a winter shadow at noon is longer than a summer shadow five hours from noon.
Direction
Which way the shadows point
A shadow points directly away from the sun. At solar noon it points due north in the northern hemisphere, outside the tropics. In the morning it points to the west of north, in the afternoon to the east.
In summer the swing is much bigger than most people expect. In London on 21 June the shadow six hours before noon points to 255°, west-south-west, because the sun is then north of east; six hours after noon it points to 105°, east-south-east. In December the sun stays in the southern sky and shadows keep to the northern half of the compass: from 319° three hours before noon to 41° three hours after. The article on sunrise direction explains the swing.
Putting it to use
Trees, fences and rows of solar panels
- Solar panel rows: rows on a flat roof or a field shade each other in winter. In London, to keep the rows clear at noon on the shortest day, the gap behind a row must be 3.7 times the height of its top edge above the next row’s bottom edge; to keep them clear from two hours before noon to two hours after, 5.4 times.
- Trees and gardens: a 10 m tree south of a garden throws its noon shadow 5.3 m in June, 12.6 m in March and 37 m in December in London. See how many hours of sun a garden gets.
- Buildings: the same factors give the reach of a house’s shadow over its neighbours through the year; which way a house should face uses them.
The shadow length calculator works out any height at any time and place, and on the map you can draw the shadow of a building or a tree directly on your plot.
Keep reading
Related articles
Which way should a house, garden or balcony face?
Hours of direct sun on every wall direction, summer and winter, for London and Madrid.
Sun elevation and azimuth, explained
The two angles that pin the sun to the sky: what they mean, how they change and how to measure them.