Garden Sunlight Calculator
Calculate garden sunlight hours by point. Compare morning and afternoon sun, twelve monthly dates, a nine-point sunlight grid and saved garden zones.
Solar times, the sky view and date controls remain available.
Light on this day
Europe/Lisbon · Select any event to move the map to that instant. Times are displayed to the minute; selection keeps the calculated instant.
Sunrise and sunset use an open horizon and atmospheric refraction. Dawn/dusk use the sun’s center at −6°, −12° and −18°. Golden light uses −4° to +6°: a planning convention, not a weather forecast. Calculation notes →
12 h 12 m modeled direct sun at this point · 0 user-entered obstacles · two-minute samples · clear sky assumption.
FROM DIRECTION TO DURATION
When does direct sunlight reach here?
2026-09-18 · Lisbon, Portugal · Europe/Lisbon
Each bar shows direct sun within that local clock hour. Clock changes can skip or repeat an hour; repeated-hour totals may exceed 60 minutes.
Read hourly values
| Local hour | Direct sun |
|---|---|
| 00:00 | 0 h 00 m |
| 01:00 | 0 h 00 m |
| 02:00 | 0 h 00 m |
| 03:00 | 0 h 00 m |
| 04:00 | 0 h 00 m |
| 05:00 | 0 h 00 m |
| 06:00 | 0 h 00 m |
| 07:00 | 0 h 36 m |
| 08:00 | 1 h 00 m |
| 09:00 | 1 h 00 m |
| 10:00 | 1 h 00 m |
| 11:00 | 1 h 00 m |
| 12:00 | 1 h 00 m |
| 13:00 | 1 h 00 m |
| 14:00 | 1 h 00 m |
| 15:00 | 1 h 00 m |
| 16:00 | 1 h 00 m |
| 17:00 | 1 h 00 m |
| 18:00 | 1 h 00 m |
| 19:00 | 0 h 36 m |
| 20:00 | 0 h 00 m |
| 21:00 | 0 h 00 m |
| 22:00 | 0 h 00 m |
| 23:00 | 0 h 00 m |
Show direct-sun time windows (1)
- 07:24 WEST–19:36 WEST
Clear-sky geometry, not a weather forecast. Two-minute sampling; time-window edges are approximate. Outdoor receiving point. 0 modeled obstacles; no terrain horizon loaded. Missing geometry is not proof of an unobstructed site.
How much sun reaches this point?
Study one bed at a time. Compare the seasons, then save this point before moving to the next.
| Date | Direct sun | Explore date |
|---|---|---|
| march Equinox2026-03-20 | 12 h 00 m | |
| june Solstice2026-06-21 | 14 h 44 m | |
| september Equinox2026-09-23 | 11 h 58 m | |
| december Solstice2026-12-21 | 9 h 18 m |
Two-minute midpoint samples. 0 modeled obstacles. Horizontal outdoor point; no window-facing filter. Clear-sky geometry, not a weather forecast.
A different season. A different light.
Keep your place and jump through the year.
Find your alignment.
Choose what you want to see from Lisbon, Portugal.
1 Choose your target
The pin is where you stand. Mark the landmark or direction you want the sun to line up with.
2 Choose the light
Set precise angles and tolerance
3 Pick your date range
Select a map target first, or open precise angles to enter a direction.
The target sets a compass direction, not the height of a landmark. Windows show when the Sun’s center is within the selected angular tolerance. Terrain, buildings and weather are not included in this alignment search. Near-horizon geometry is not a guarantee of a visible sunrise.
Garden Sunlight Hours and Shade Calculator
A garden’s open-horizon daylight is not the same as sunlight reaching a bed. Place a growing point and compare the clear-sky ray with the screens you have measured; the result counts modeled direct sun, not cloudy-day sunshine.
Use this when: Use this when the primary question is direct sun at one outdoor point, such as a garden bed, across representative dates.
Inputs this tool uses
- One growing point inside the bed, rather than a street address or yard centroid.
- A date and local time zone, with the same dates and obstacle assumptions used for comparisons.
- Measured screen heights, widths, locations and rotations. A tree is an opaque screen approximation, not a foliage-transmission model.
What this tool calculates
- Estimated direct-sun duration using two-minute midpoint intervals
- Changes between growing-season dates at the selected outdoor point
- Shade from explicit, user-modeled opaque screens
- Open-horizon daylight as separate context
- Morning and afternoon direct-sun totals and time windows
- Twelve representative monthly dates and a nine-point flat-ground sunlight preview
- Same-date comparison of up to four saved scenes
How the estimate is made
SunCarta integrates the selected civil day in real elapsed UTC intervals using two-minute midpoints, shortening the last interval when needed. A sample counts when the geometric solar center is above the modeled horizon (0° with the flat default) and no modeled screen blocks the outdoor point. No window-facing direction is applied. A 23-hour or 25-hour DST date is not forced into 24 hours.
How to use it
- 01
Pin one growing spot
Place the point inside the bed rather than using the garden’s street address as a substitute.
- 02
Draw the skyline
Add measured obstructions as opaque screens. Compare plausible heights where measurements are uncertain.
- 03
Compare seasons
Check dates near midsummer, the equinoxes and midwinter. Save a separate setup for a different bed.
Worked example
For an illustrative 90-minute clear interval, 45 full two-minute samples contribute 1 h 30 min. That sampling example is not a field observation. Repeat with the same dates and dimensions at the bed’s centre and edges; one summer result is not a guarantee of plant performance.
How to read the result
Direct-sun hours
The total counts elapsed sampled intervals with an unblocked solar ray above the geometric horizon. A garden point has no window-facing condition.
Plant context
Use the result to plan a site observation. Plant needs, clouds, heat, soil and reflected light require separate evidence.
What to do next
Save each garden bed as a scene, then use Compare up to four saved garden points. Recalculate the same date for each saved scene. Explore the nine-point preview for nearby differences; it excludes terrain and is not a continuous heatmap.
Limits you should know
- Tree screens do not resolve leaf gaps, pruning or seasonal transmission.
- Unknown obstacle dimensions stay uncertain; test a plausible range before drawing a conclusion.
- The annual heatmap is open-horizon elevation, not an annual garden-sun calendar.
Questions about this calculator
Which date should I use for a vegetable garden?
Check the beginning, middle and end of the crop’s actual growing season using consistent dimensions. A midsummer result alone may overstate spring or autumn exposure.
Can I test several garden beds?
Yes. Move the point, save named scenes in this browser, and repeat the same dates. Compare shows up to four dates or two places; it is not a measured parcel-wide exposure map.
Methodology version 2.0 · Reviewed September 20, 2026