SunCalc Sunlight Planner: Map Your Garden’s Sun Exposure

What Is SunCalc Sunlight Planner?

SunCalc is a free online sunlight and shadow simulation tool that shows the sun’s position, sunrise and sunset times, and shadow lengths for any location on Earth on any date. Designed with a clean, interactive map interface, it allows gardeners, architects, photographers, and outdoor enthusiasts to visualize exactly how sunlight will move across a specific site throughout the day.

For gardeners, understanding sun exposure is one of the most critical factors in site selection and plant placement. Most vegetables require 6 to 8 hours of direct sunlight daily, and even a few hours of unexpected shade from a nearby building, fence, or tree can significantly reduce yields. SunCalc lets you enter your garden’s address or GPS coordinates, select a date, and watch an animated simulation of how sunlight and shadows will interact with your space from dawn to dusk.

The tool goes beyond simple sunrise and sunset times by modeling the actual path of the sun across the sky. It displays the sun’s altitude and azimuth at any given moment, the length of shadows cast by objects of a specified height, and the total hours of daylight. This level of detail makes SunCalc one of the most powerful free tools available for garden planning, especially for urban and suburban lots where surrounding structures create complex shade patterns that change with the seasons.

Key Features

Interactive Map Interface: Search for any address or GPS coordinate worldwide and see an overhead satellite view with sun position overlays.
Date-Specific Sun Simulation: Select any date of the year to see exactly where the sun will rise, travel, and set on that day — critical for seasonal planning.
Shadow Length Calculator: Enter an object height and SunCalc computes the shadow it will cast at any time of day, helping you predict shade from fences, buildings, and trees.
Sunrise, Sunset, and Daylight Hours: Instantly see precise sunrise, solar noon, and sunset times along with total daylight duration for your chosen location and date.
Sun Path Visualization: A dome diagram shows the complete arc of the sun across the sky, making it easy to identify periods of direct sunlight versus shade at your garden site.
Golden Hour and Twilight Data: Photographers and gardeners alike benefit from knowing exactly when golden hour light occurs and when civil twilight begins and ends.

Pros and Cons

Pros	Cons
Completely free with no account required	Requires internet access to use
Works for any location worldwide	Does not account for future tree growth or seasonal canopy changes
Highly accurate astronomical calculations	Shadow modeling assumes flat terrain
Simple, intuitive interface	No mobile app (browser only)
Date-specific data for full year planning	Cannot model shade from nearby hills or slopes

Pricing

SunCalc is 100% free to use. There are no premium tiers, advertisements that block functionality, or account registration requirements. The tool is available at suncalc.org and works entirely within your web browser. It was created as an open-source project and remains freely accessible to anyone who needs sun position data. For gardeners on a budget, it provides professional-grade solar planning capabilities at zero cost — an exceptional value compared to commercial site analysis software that can cost hundreds of dollars.

How to Use SunCalc Sunlight Planner

Using SunCalc for garden planning is straightforward:

Step 1: Go to suncalc.org in your web browser. The map will load centered on a default location. Click on the search bar and enter your garden’s address, ZIP code, or GPS coordinates.

Step 2: Use the date selector at the top of the page to choose the date you want to analyze. For garden planning, start with the summer solstice (June 21 in the Northern Hemisphere) to see your maximum sun exposure, then check the spring and fall equinoxes to understand seasonal changes.

Step 3: Drag the timeline slider to watch the sun’s position change throughout the day. Observe the yellow sun path line on the map to see which areas of your garden receive direct light and which fall into shadow at each hour.

Step 4: Use the shadow calculator feature by entering the approximate height of nearby structures, fences, or trees. SunCalc will display the shadow length at each time of day, helping you map shade zones on your property.

Step 5: Record your findings. Sketch a simple map of your garden and note which areas receive full sun (6+ hours), partial sun (3–6 hours), and full shade (less than 3 hours). Use this map to place sun-loving crops like tomatoes and peppers in the brightest spots and shade-tolerant crops like lettuce and spinach where shade is unavoidable.

Who Should Use This Tool?

SunCalc is essential for new gardeners who are choosing where to install raised beds or in-ground plots and need to verify sun exposure before building. Urban gardeners dealing with shade from buildings, fences, and neighboring trees will find it especially valuable for mapping complex light patterns. Landscape designers can use it during client consultations to show how proposed plantings will interact with available sunlight. It is also useful for homesteaders and permaculture planners who need to place fruit trees, greenhouses, and annual vegetable beds for optimal solar gain. Even experienced gardeners benefit from checking SunCalc when planning fall and winter gardens, as sun angles change dramatically with the seasons.

Frequently Asked Questions

How accurate is SunCalc’s shadow modeling?

SunCalc’s astronomical calculations are highly accurate. However, the shadow modeling assumes flat terrain and does not account for topography like hills, slopes, or elevation changes. For most residential garden planning, the accuracy is more than sufficient.

Can I use SunCalc on my phone?

Yes. SunCalc works in mobile browsers on both iOS and Android devices. While there is no dedicated mobile app, the web interface is responsive and functional on smaller screens.

Does SunCalc work for the Southern Hemisphere?

Absolutely. SunCalc works for any location worldwide. Simply search for your address or coordinates and the tool will display accurate sun position data for your hemisphere and latitude.

Can SunCalc account for shade from trees with leaves versus bare branches?

No. SunCalc models hard shadows from opaque objects but cannot simulate the dappled shade that deciduous trees create when in leaf. For deciduous tree shade, consider the tool’s predictions as a rough guide and supplement with on-site observation.

What is the best date to check for maximum garden sun exposure?

Check the summer solstice (around June 21 in the Northern Hemisphere) for maximum sun height and longest day length. For a complete picture, also check the spring and fall equinoxes (around March 20 and September 22) to understand how sun patterns shift during the growing season.