What this finance solver does
The Finance Solver answers the five finance questions people ask most often: the payment on a loan, how much regular saving grows to, the net present value (NPV) of a project, its internal rate of return (IRR), and the effective annual rate behind an APR. Pick the question type, enter your numbers and the answer appears straight away.
Unlike an AI chatbot, it doesn't generate the answer as text. Every figure is calculated with the standard formula, so there are no rounding slips or invented steps. When we tested an AI model on these same five questions, three of its worked solutions contained wrong intermediate numbers. This tool shows the working with your own numbers, so you can follow each step or copy it into your notes.
How to use it
- Choose a question type: Loan payment, Savings growth (FV), NPV, IRR or APR → effective rate. Each one opens with a worked example already filled in.
- Replace the example values with your own. Rates are entered as percentages, so type 7.9 for 7.9%.
- For NPV and IRR, enter today's cost as a positive number and the later cash flows separated by commas, one per year (or per period).
- For savings, choose whether deposits go in at the start or the end of each month. Start-of-month deposits earn one extra month of interest each.
- Read the answer, the working underneath, and the spreadsheet formula. Copy the formula into Excel or Google Sheets to confirm the answer yourself.
Worked example: comparing a project's NPV and IRR
A project costs 50,000 today and returns 15,000, 18,000, 20,000 and 12,000 over the next four years. At an 8% discount rate, the present values are 13,888.89, 15,432.10, 15,876.64 and 8,820.36. They add up to 54,017.99, so the NPV is 4,017.99. A positive NPV means the project earns more than 8%.
The IRR tab answers the follow-up question: exactly how much more? It finds the rate where NPV falls to zero, which here is 11.62%. If your required return is below 11.62%, the project passes. If it is above, it doesn't.
Common mistakes this helps you avoid
Rounding halfway through. Rounding (1 + r) to four decimal places can move a loan payment by several cents, and a long NPV by tens of dollars. The solver keeps full precision until the final answer.
Discounting today's cost. In a spreadsheet, NPV() assumes its first value arrives one period from now. Putting the initial cost inside the function shrinks the answer, to 3,720.36 instead of 4,017.99 in the example above. The formula shown here keeps the cost outside.
Mixing up APR and effective rate. An 18% APR charged monthly costs 19.56% a year once interest compounds. Use the effective rate when comparing products that compound differently.
Frequently asked questions
Is this a finance AI solver?
No. It uses exact formulas instead of an AI model, so the answer is the same every time and matches Excel. For a word problem, work out which of the five question types it is, then enter the numbers here.
Why is my answer slightly different from my textbook?
Usually because of rounding or a timing convention. Textbooks often round factors from tables to four decimal places. Also check whether payments happen at the start or end of each period, and whether the rate is per year or per month.
Can I use it for periods other than years?
Yes, for NPV and IRR. Enter the rate per period, and the IRR you get is per period too. For monthly cash flows, a monthly IRR of 1% is about 12.68% a year.
Why does IRR sometimes say there is no answer?
IRR exists only when NPV crosses zero, which normally needs at least one negative and one positive cash flow. If every cash flow has the same sign, no rate makes NPV zero.
Is the loan payment the same as an EMI?
Yes. An EMI (equated monthly instalment) is the fixed monthly payment on an amortising loan. For a full month-by-month schedule, use the Loan EMI Calculator.