A tree’s shadow moves with the seasons — a spot that’s baked in full sun in December might be deeply shaded in July. Enter a tree’s height, canopy width, and your latitude to see exactly how far the shadow reaches at noon, mid-morning, and mid-afternoon across the four key seasons.
Pro tip: A well-placed shade tree can cut summer cooling costs by 20–30%. The magic spot is on the west side of your house, about 15–20 feet from the wall, where it blocks the brutal afternoon sun of June–August without shading the low southern winter sun that heats the house for free in January.
How to Use the Canopy Shade Calculator
Enter the tree’s height and mature canopy width. Pick your latitude from the dropdown (the closer you are to the equator, the shorter the shadows). Choose a season, and the calculator uses the sun’s actual altitude angle on that date at solar noon to work out exactly how far the tree’s shadow falls and how much ground area it covers. Toggle between the four seasons to see how dramatically shadows change across the year.
The Math Behind the Shadow
The calculation starts with the sun’s solar altitude angle — the angle between the horizon and the sun. At solar noon, this angle is given by altitude = 90° – latitude + declination, where declination is the sun’s position relative to the equator (+23.45° at summer solstice, –23.45° at winter solstice, 0° at the equinoxes).
Shadow length is then simply height / tan(altitude). So a 40-foot tree at 40°N latitude on the summer solstice has a sun altitude of 73.45°, producing a noon shadow of about 12 feet. The same tree on the winter solstice has a sun altitude of only 26.55°, producing a noon shadow of roughly 80 feet — nearly 7 times longer. This is why deciduous trees are perfect for south-facing homes: dense summer shade when you need it, and a long low winter sun slipping through bare branches to warm the house when you want it.
Strategic Placement for Energy Savings
The U.S. Department of Energy estimates that three well-placed shade trees can save a homeowner $100–$250 per year in cooling costs, with full savings realized when the canopy matures in 10–20 years. The placement rules that maximize savings:
- West and southwest walls take the worst summer heat beating. Plant deciduous shade trees 15–20 feet from these walls. At that distance a mature 40-foot canopy will shade most of the wall and roof edge during the hottest afternoon hours.
- Never plant evergreens south of the house in heating climates. They block the low winter sun that provides free heating, costing you more in heating than you save in cooling.
- East side trees shade morning heat and are a lower priority than west-side trees but still helpful for east-facing bedrooms and kitchens.
- North side trees provide windbreak benefits in cold climates but virtually no shade value. Evergreens work best here as winter wind screens.
- Over air conditioner compressors: a shade tree that cools the AC unit by 10°F can improve its efficiency by up to 10%. Leave at least 3 feet of clearance for airflow.
The Garden Planner’s Perspective
Shadows also define what you can grow where. A spot that gets 6+ hours of direct sun between 10 AM and 4 PM is full sun — enough for tomatoes, peppers, squash, and most flowers. A spot with 4–6 hours is partial sun, best for leafy greens, herbs, and root crops. Less than 4 hours is shade, where only shade-tolerant plants like hostas, ferns, astilbe, and impatiens will thrive.
Use this calculator to plot which corner of your yard falls into which category at different seasons. A bed that’s in full sun at the spring equinox might be heavily shaded by midsummer once a large nearby tree has leafed out. Planning around this prevents the common mistake of planting tomatoes in April sun and watching them get choked out by canopy shade in July.
Why Morning and Afternoon Shadows Are Longer
The hero result shows the shortest shadow of the day, cast at solar noon when the sun is highest. Shadows at 9 AM and 3 PM are significantly longer because the sun is lower in the sky. At sunrise and sunset, shadows stretch to infinity as the sun crosses the horizon. The Pro hourly shade map walks through the full day, showing how the shadow sweeps from west (morning) through north (midday, in the northern hemisphere) to east (afternoon) — this sweep is what determines whether a specific spot in your yard gets any usable sun at all.
Latitude Matters More Than You Think
A tree in Miami (25°N) casts a dramatically shorter noon shadow at any time of year than the same tree in Minneapolis (45°N). At summer solstice in Miami, the sun is nearly overhead at 88°, so a 40-foot tree casts a noon shadow of barely 1.4 feet. In Minneapolis the same tree on the same day casts a shadow of about 15 feet. In winter the contrast is even more extreme: Miami’s winter noon sun is still at 41°, giving a 46-foot shadow — while Minneapolis’s winter noon sun is at only 22°, giving a 100-foot shadow. This is why you can get away with planting a tree much closer to a south-facing window in Florida than you can in the upper Midwest.
Planning the rest of your tree care? Use the Tree Watering Calculator to figure out how much water your shade tree needs each week, or check the Tree Pruning Calendar to know when to shape it.