What does Rule of 72 do that other Finance pages on this site do not?

Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months. Short version: Years to double at a rate, or rate for a target years.

Does Rule of 72 upload my file or text to Tool-You servers?

No. Rule of 72 runs in this browser tab. Files stay on the device. Limit note: Approximation only. Fill rate or target years (not both needed).

Should I use Compound Interest Calculator instead of Rule of 72?

Use Rule of 72 when you need Years to double at a rate, or rate for a target years. Use Compound Interest Calculator when you need Project compound growth with optional contributions. They share a category (Finance) but not the same job.

What are the limits of Rule of 72?

Approximation only. Fill rate or target years (not both needed). Also: Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.

Rule of 72

Years to double at a rate, or rate for a target years.

Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.

What Rule of 72 does

Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.

Practical limit for Rule of 72: Approximation only. Fill rate or target years (not both needed). That is why output can differ from heavy desktop Finance software. Read the tool-specific note again: Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.

How to use Rule of 72

Confirm you need Rule of 72, not Compound Interest Calculator (Project compound growth with optional contributions.). Address: /finance/rule-of-72.
Enter the numbers or dates Rule of 72 uses. Years to double at a rate, or rate for a target years.
Read the result as Rule of 72 defines it — not as Loan Calculator (Payment by schedule, with optional extras.). Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.
Rule of 72 is an estimate in the browser, not professional advice. Approximation only. Fill rate or target years (not both needed).
Need a different formula? Try Loan Calculator (Payment by schedule, with optional extras.) instead of stretching Rule of 72.

When not to use Rule of 72

Skip Rule of 72 when a neighbor tool matches better — start with Compound Interest Calculator or Loan Calculator — or when the description already warns the job will fail. In the tool’s own words: Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.

Questions about Rule of 72

What does Rule of 72 do that other Finance pages on this site do not?: Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months. Short version: Years to double at a rate, or rate for a target years.
Does Rule of 72 upload my file or text to Tool-You servers?: No. Rule of 72 runs in this browser tab. Files stay on the device. Limit note: Approximation only. Fill rate or target years (not both needed).
Should I use Compound Interest Calculator instead of Rule of 72?: Use Rule of 72 when you need Years to double at a rate, or rate for a target years. Use Compound Interest Calculator when you need Project compound growth with optional contributions. They share a category (Finance) but not the same job.
What are the limits of Rule of 72?: Approximation only. Fill rate or target years (not both needed). Also: Rule of 72 approximation. Fill rate for years, or target years for required rate. Also shows months.