Formulas, assumptions, and limits are shown on each calculator.

Toolkit Shelf calculators are meant for quick estimates, comparisons, and everyday planning. Calculator pages include the relevant formula or method whenever possible.

Results can change based on rounding, assumptions, local rules, tax treatment, fees, or personal circumstances. Money and housing calculators are planning aids, not financial, legal, or tax advice.

If you notice a formula issue or a confusing explanation, use the contact page to send a correction request.