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Convert a period’s profit and principal into a linear annualized return using a 365-day basis.
Interest or earnings obtained during the investment period, excluding the principal.
Please enter principal, profit, and investment period to calculate the annualized return rate.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
This calculator scales a single period's profit against its principal to a 365-day year. It uses simple, linear annualization: annualized return (%) = profit ÷ principal × 365 ÷ converted days × 100. The period return is profit ÷ principal × 100. No reinvestment or compounding is assumed. The SEC's Investor.gov glossary notes that annual return has more than one calculation method, so the method matters when comparing figures (SEC Investor.gov: Annual Return, checked September 29, 2026).
Enter a principal, the profit or loss earned over the period, and the period length. Use matching units for principal and profit: for example, dollars for both, or cents for both. There is no currency conversion. The result also shows the period's total return, a daily rate, the entered profit, principal plus profit, and the converted day count. Rate outputs are displayed as percentages; the annualized and total rates show two decimal places, while the daily rate shows four.
The period can be entered in days, months, or years. A month is treated as exactly 30 days and a year as 365 days; the tool does not follow calendar month lengths or leap years. If the actual elapsed time is known in days, using the day unit avoids the fixed-month approximation.
converted days = period × unit day factorannualized return = (profit ÷ principal) × (365 ÷ converted days) × 100%daily return = (profit ÷ principal) ÷ converted days × 100%For a fixed input profit and principal, the annualized figure scales in direct proportion to 365 divided by the period's converted days. This is a calculation convention, not a claim that the same result will recur throughout a year.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Enter the amount originally invested as the principal. It must be greater than zero.
Enter only the profit or loss for that period. Do not add the principal to this field. Use a negative amount for a loss.
Enter the period and choose days, months, or years. Months convert at 30 days each; years convert at 365 days each.
Read the annualized figure alongside the total-period return and converted days. The latter values show the actual period basis behind the scaled result.
For example, a $10,000 principal with $300 profit over 90 days gives a 3.00% period return. The annualized result is 3% × 365 ÷ 90 = 12.17% after rounding. The daily rate is about 0.0333%, the displayed profit is $300, and the total at maturity is $10,300.
Use cases
See how the tool fits into real work and everyday tasks.
If you know the principal, realized profit, and exact number of days for a one-time holding period, use the result as a standardized arithmetic summary. Keep the period return visible because it is the return actually earned over that interval.
When organizing several single-period results, record each principal, profit, day count, and formula convention. This makes it easier to see whether two reported annual figures use the same linear method and 365-day basis.
For a single principal and period profit, the calculation can help check a simple-interest figure when the relevant agreement uses a 365-day basis. Confirm the contract's day-count convention and included fees separately.
Q&A
Find concise answers to common questions and confusing cases.
No. It multiplies the period return by the ratio of 365 days to the converted period. It does not repeatedly reinvest or compound the profit, so it is not a compounded annual growth rate or APY.
Subtract the principal from the ending amount, then enter the difference as profit. For instance, a $10,300 ending amount after a $10,000 principal means profit is $300.
The month option always uses 30 days per month. Calendar months vary in length, so use the actual elapsed day count when you need the result based on exact dates.
Yes. Enter a negative profit amount. The total and annualized return rates will be negative when the other inputs are valid.
Notes
Review scope, result limitations, and important precautions before use.
A short-period result may become a much larger annualized percentage because the same period return is scaled across a 365-day year. That number describes the entered period under a linear formula; it does not forecast future performance, promise repeatability, or account for the risk of an investment.
This calculation is for one principal and one net profit or loss over one period. It does not model deposits, withdrawals, interim dividends, or reinvestment. It is not a regulatory APR, a loan cash-flow analysis, or an internal rate of return. Fees, taxes, and inflation affect the result only if already reflected in the profit amount. For an account, product, or loan, follow its disclosed terms and applicable calculation convention.
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