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Sunlight Hours Estimator

Estimate daily sun exposure for a garden area based on location, time of year, and orientation.

Location

Positive = Northern hemisphere, Negative = Southern hemisphere

Date

Garden Orientation

Which direction does your garden face? This affects how much direct sun it receives.

S
South
W
West
E
East
N
North
Angle above horizon blocked by buildings, trees, or fences (0 = no obstruction).
The estimate updates as you change location, date, or orientation.

How It Works

This tool uses standard astronomical formulas to calculate the sun's position throughout the day for any location and date. It then estimates how much direct sunlight your garden receives based on orientation and obstructions.

Solar Declination

The sun's declination (its angle relative to the equator) changes throughout the year, reaching +23.44° at the summer solstice and −23.44° at the winter solstice.

δ = 23.44° × sin(360° / 365 × (284 + N))

Where N is the day of the year (1–365).

Daylight Duration

The total hours of daylight depend on your latitude and the solar declination. Locations closer to the poles experience more extreme variation between seasons.

Hour Angle = arccos(−tan(φ) × tan(δ))
Daylight = 2 × Hour Angle / 15° hours

Effective Garden Sun

Not all daylight hours mean direct sun for your garden. The effective sun exposure depends on:

  • Orientation — South-facing gardens (Northern hemisphere) receive the most sun; north-facing receive the least.
  • Obstructions — Buildings, trees, or fences that block low-angle sunlight reduce morning and evening exposure.
  • Sun altitude — Low sun angles early and late in the day contribute less effective light for plant growth.

Sun Exposure Categories for Plants

Category Hours of Direct Sun Suitable Plants
Full Sun6+ hoursTomatoes, peppers, squash, corn, melons, roses
Partial Sun3–6 hoursLettuce, spinach, herbs, beans, peas, broccoli
Shade< 3 hoursFerns, hostas, mosses, some mushrooms

Tips for Maximizing Garden Sunlight

Orientation

  • In the Northern hemisphere, south-facing plots get the most sun
  • Orient garden rows north-to-south so both sides receive equal light
  • Place tall plants on the north side to avoid shading shorter ones

Reducing Shade

  • Prune overhanging tree branches to let more light through
  • Use reflective mulch or light-colored surfaces to bounce light
  • Consider raised beds to elevate plants above low fences
  • Use containers that can be moved to follow the sun

Embed This Util

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML: 


    

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