Greenhouse Size Calculator
Find the right greenhouse size for what you want to grow. Count your trays, pots and plants, tell us how you will use the space, and see the greenhouses that fit.
How it works
How big a greenhouse do I need?
Start with the space your plants take up on benches and in beds, then add walkways. In a typical hobby greenhouse, benches and beds fill about 60% of the floor and walkways take the rest.
| What you grow | Space each |
|---|---|
| Seed tray, 10 x 20 in | 1.4 sq ft |
| Small pot, up to 8 in | 0.5 sq ft |
| Tomato, pepper or cucumber plant | 4 sq ft |
| Potted citrus or fig tree | 9 sq ft |
| Potting bench | 12 sq ft |
Almost every greenhouse owner wishes they had bought a bigger one, so we add 25% room to grow by default. A bigger greenhouse also holds its temperature more steadily than a small one.
Questions
Greenhouse size FAQ
What is a good size for a first greenhouse?
For most home gardeners, 8 x 10 to 10 x 14 ft is a good start. It fits a potting bench, benches on both sides and room for a few large plants, without taking over the yard.
Is an 8 x 8 greenhouse big enough?
An 8 x 8 ft greenhouse fits about 10 to 12 seed trays or 6 to 8 large plants with a single walkway. It suits seed starting and a few tomatoes, but many people outgrow it within a year or two.
How much space do tomatoes need in a greenhouse?
Allow about 4 sq ft per tomato plant, which is roughly 18 to 24 inches apart, plus walkway space to reach them.
Does a bigger greenhouse cost more to heat?
Yes, but not in proportion to the floor area. A larger greenhouse has more air and thermal mass, so it holds heat better. Use our heating cost calculator to compare sizes.
More tools
Other greenhouse calculators
- Heater Size CalculatorHow many BTUs it takes to keep your greenhouse warm on the coldest night.
- Heating Cost CalculatorWhat a winter of heating will cost with electric, propane or natural gas.
- Fan and Ventilation CalculatorThe exhaust fan CFM and vent openings that keep summer heat down.
- Snow Load CalculatorHow much the snow on your roof weighs and when to brush it off.
- Foundation CalculatorConcrete, gravel, pavers and lumber for your greenhouse base.
- Shade Cloth CalculatorThe right shade percentage and cloth size for your greenhouse.
- Grow Light CalculatorHow many grow lights it takes to give your plants enough light in winter.
- Rainwater CalculatorHow much water your greenhouse roof can collect for your plants.
Want a second opinion?
Tell us about your greenhouse and where you live, and we will help you get it right.
Call 678-408-8222Send us a message