Budget Rules
Proven mental models for budgeting, saving, and building long-term wealth. Pick one rule and start.
50·30·20 Rule
Split your take-home income into Needs (50%), Wants (30%), and Savings (20%). The simplest budgeting framework that actually works.
Open calculator →Emergency Fund Rule (3-6)
Calculate how much cash reserve you need for 3 to 6 months of essential expenses. Build a buffer before market investing.
Open calculator →Pay Yourself First
Automate a savings transfer on income day so your future goals are funded before discretionary spending begins.
Open calculator →The 1% Rule
Increase your savings rate by 1% periodically to build wealth through small, sustainable behavioral upgrades.
Open calculator →The Rule of 72
Use the 72 shortcut to quickly estimate how many years your money may take to double at a given return rate.
Open calculator →4% Retirement Rule
Estimate retirement corpus using the 4% withdrawal heuristic (or 25x annual expenses) and test baseline sustainability assumptions.
Open calculator →20/4/10 Car Rule
Evaluate car affordability by checking down payment ratio, loan duration, and monthly transport cost against income limits.
Open calculator →28/36 Mortgage Rule
Measure mortgage affordability with housing and total debt-to-income thresholds used as a conservative screening framework.
Open calculator →60:20:20 Rule
A budgeting framework for higher essential costs while preserving a 20% savings and 20% wants allocation.
Open calculator →40:20:40 Rule
A savings-heavy budgeting variant that targets high long-term contribution rates when fixed costs are controlled.
Open calculator →