Is this accurate enough to decide?

It is accurate for the assumptions you enter. Use it for planning, then validate the most sensitive inputs with primary sources when stakes are high.

What if I don’t know an input?

Model a range (low/base/high). If the decision flips across the range, that input is your next research priority.

Run a base case, a downside case, and a managed response case. If the plan survives the downside, the decision is more robust.

Real Estate Desk

Avoid common errors that make rent vs buy decision calculations misleading: unit mismatches, missing costs, and optimistic assumptions.

Real EstateUpdated April 12, 20261 min read

Most mistakes are not complex—they’re missing pieces. rent vs buy decision looks simple until a real-world constraint is omitted.

Use this checklist to spot errors before you commit to a decision based on the output.

Monthly vs annual confusion is the #1 error. Label each input before typing it.

If the output surprises you, simplify the scenario and change one input at a time.

If a cost exists in reality (fees, taxes, churn, waste), it must exist in the model.

If outputs like net worth path and break-even year look too good, a missing cost is usually the reason.

Always run a downside case. If the downside breaks the plan, your base case is not safe enough.

Start conservative on home price and downpayment when uncertain.

Interactive Tool

Model the numbers behind Common rent vs buy decision Mistakes (and How to Avoid Them)

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