Garden Suite & ADU Cost Calculator for Toronto
Use this free garden suite cost calculator to see a realistic budget range for a garden suite, laneway suite or other ADU in Toronto and the GTA. Answer a few quick questions about your project and get your estimate in about a minute.
For context: most Toronto garden suites need an all-in budget of roughly $150,000 to $400,000+, with construction alone typically running $270 to $310+ per square foot. Where your project lands in that range depends on size, site access, utility servicing, foundation needs, design and finishes. For the full breakdown, see our garden suite cost guide for Toronto.
How to Get the Most Accurate Estimate
The calculator is only as precise as the details you give it. Before you start, have these ready:
- Your target size: the square footage you want, not the size of your backyard. Toronto zoning limits footprint, height and setbacks, so check what your lot allows.
- Site access: whether equipment can reach the backyard through a laneway, a side yard or not at all. Tight access adds labour and time.
- Utility route: the distance from the house to where the suite will sit. Water, sewer and electrical connections usually cost $8,000 to $18,000, depending on distance and trenching.
- Design route: whether you plan to use a ready-made suite design or a fully custom plan.
- Finish level: standard, upgraded or high-end. Finishes, glazing and millwork can move the price per square foot noticeably.
What Drives Your Garden Suite Cost
Two suites of the same size can differ by tens of thousands of dollars. These are the factors that matter most:
| Cost driver | Why it matters |
|---|---|
| Size | The biggest single factor. But smaller suites cost more per square foot, because the kitchen, bathroom, foundation and mechanical systems are needed regardless of size. |
| Build complexity | Straightforward builds start around $270–$285/sq ft. Restricted access or upgraded finishes push it to $285–$300, and custom or site-constrained builds to $295–$310+. |
| Utility servicing | Typically $8,000–$18,000, driven by distance to existing connections and possible service upgrades. |
| Foundation and soil | Poor soil, slopes or nearby trees can require a more engineered foundation. |
| Permits and approvals | A suite that fits zoning as-of-right avoids a minor variance, which adds a $5,011.08 City application fee plus redesign time. See our garden suite permit guide. |
| HST | 13% HST applies to most construction costs. Always check whether a quote includes it. |
Costs Many Estimates Leave Out
Online numbers often show construction only. When you compare your result with builder quotes, make sure each one states whether these are included:
- Architectural design, engineering and permit drawings
- Building permit fees (about $18.56 per m² plus $56.33 for the new unit), plus plumbing and HVAC permits
- The TCDSB Education Development Charge, currently $3,893 per dwelling unit and adjusted each December
- Utility connections, trenching and site restoration
- 13% HST
- A 10%–15% contingency, kept as your own reserve for the whole build
Municipal development charges are typically $0 for a garden suite added as the second unit on a residential lot.
Why You Get a Range, Not a Fixed Price
No calculator can see your soil, your trees or exactly where your sewer line runs. That is why your result is a range. The lower end assumes few surprises; the upper end leaves room for real site conditions. To turn the estimate into a fixed, itemized number, the next step is a site assessment.
Book a free site check and we will review your lot, zoning and servicing route, then give you a detailed proposal.
From Estimate to Move-In: Next Steps
- Free site check: confirm what your lot allows and refine the budget.
- Zoning and permits: we prepare drawings and handle the permit process.
- Design: choose from our suite designs or go custom.
- Financing: explore garden suite financing options.
- Build and rent: we build the suite; if you plan to rent it out, see our rental guide.
It gives a planning-level range based on current Toronto construction costs. It is designed for early budgeting and comparing options. A final price needs a site assessment and an itemized proposal.
Yes. Laneway suites and garden suites use similar construction, so the estimate is a good starting point. Laneway projects can differ in access, servicing and fire access requirements. Learn more about laneway suites in Toronto.
Construction alone typically runs about $162,000 to $186,000+ for 600 sq ft. After design, permits, servicing, contingency and HST, the all-in budget is higher. Run the calculator with your own details for a closer number.
Every suite needs a foundation, kitchen, bathroom, heating and cooling, and utility connections. In a smaller suite, those fixed costs are spread over fewer square feet, which raises the price per square foot.
Possibly. A suite rented as a tenant’s long-term home may qualify for federal and Ontario new residential rental property rebates. Short-term rentals generally do not qualify. Rules depend on when construction starts and the suite’s value, so speak with a GST/HST accountant. Our cost guide explains the current rebates.
A legal garden suite can bring in rental income, house family members or add flexible living space. These benefits can strengthen your property’s appeal and support resale value.