How to Use the NPV Calculator
Use this browser-based calculator to discount an entered cash-flow series at one annual rate and calculate its net present value (NPV). Choose evenly spaced periods or actual calendar dates, then review the formula, timeline, discount factors, and present values in the result.
Choose the entry mode that matches your cash-flow schedule, enter the timing and signed amounts, and select Calculate.
- Select By period (Year 0, 1, 2, ...) or By calendar date.
- In period mode, set Period length (years). Period 0 is today. The calculator starts with three period rows; use Add cash flow for more.
- In date mode, set Valuation date and enter a date for each cash flow. The calculator starts with two dated rows; use Add cash flow for more.
- Enter each amount with its intended sign: use negative amounts for outflows and positive amounts for inflows. Labels are optional.
- Enter Annual discount rate (%), then select Calculate.
- Use Reset to clear the inputs. After a result appears, use Copy result or Download result (.txt).
How the Calculation Works
The calculator discounts each cash flow to the valuation point and adds the present values:
Discount factor DF(t) = 1 / (1 + r)^t
NPV = Σ CFt × DF(t) = Σ CFt / (1 + r)^t
- In period mode, use nonnegative numeric periods. The period value is multiplied by Period length (years).
- In date mode, the calculator converts the gap between each cash-flow date and Valuation date using a 365.25-day year.
- Annual discrete compounding and one flat annual rate are used for every cash flow.
- Cash-flow signs are taken from the amounts you enter.
Results and Exported Details
The result shows NPV, the rate used, and the number of cash flows. It also includes a timeline, a cash-flow table with time, signed amount, discount factor, and present value, plus a plain-text result that you can copy or download as a .txt file.
Validation and Date Behavior
Enter a discount rate greater than -100% and a period length greater than zero. Period mode requires at least one cash flow; its period entries must be numeric and at least 0. Dated mode requires a valid Valuation date, at least two dated cash flows, and a valid date and amount for each completed row.
Fully empty rows are skipped. If a row has a period or date but no amount, or an amount but no period or date, the calculator shows an error instead of calculating. Dates before the valuation date are accepted and produce negative time values, so choose a valuation date appropriate to the cash flows you are evaluating.
Limitations and Input Handling
The calculation uses the cash flows and rate you enter in the browser, and the calculator does not submit those calculation inputs. It does not fetch live market data, estimate rates, or provide personalized financial advice. You must supply the discount rate.
Frequently Asked Questions
What is net present value (NPV)?
Net present value is the sum of a series of cash flows, each discounted back to today at a chosen discount rate. It tells you what a stream of future cash inflows and outflows is worth in today's money. A positive NPV means the discounted inflows outweigh the discounted outflows at that rate; a negative NPV means the opposite.
What discount rate should I use?
This calculator does not estimate a discount rate for you - you must supply it. Common choices include a required rate of return, a weighted average cost of capital (WACC), or a comparable investment's expected yield, but selecting the right rate depends on judgment and context this tool does not have.
What is the difference between entering cash flows by period versus by date?
By period assumes cash flows land on evenly spaced anniversaries (Year 0, Year 1, Year 2, and so on) using a period length you set, which is the standard textbook NPV convention. By date lets you enter the actual calendar date of each cash flow, and the calculator measures the exact time in years between each date and your chosen valuation date using a 365.25-day year - useful when cash flows are irregularly spaced.
What sign convention does this calculator use?
Outflows (money paid out, such as an initial investment or a cost) are entered as negative amounts, and inflows (money received) are entered as positive amounts. The cash-flow table labels every entry as an inflow or outflow so the convention is never ambiguous.
Does this tool fetch live interest rates or market data?
No. This calculator only uses the cash flows and discount rate you type in. It does not fetch live interest rates, market prices, or account data, and does not provide personalized financial or investment advice.