Comparing rent vs buy often requires a time horizon. If rent is $1,800/month and a comparable mortgage (including taxes and insurance) is $2,100/month, the monthly difference is easy to compute. Over a chosen horizon — say five years — multiply monthly amounts by months to compare cash flows. This simplified comparison excludes equity or tax effects to isolate pure cash outflows. Making that arithmetic explicit helps you see when higher monthly mortgage payments might be offset by equity or other benefits. (Numbers are illustrative.)