Finance Calculator: TVM, Loans, NPV/IRR, ROI & Budget

The Finance workbench is nine panels on one route: TVM, Compound Interest, Loan, NPV / IRR, ROI, Budget, Prepayment, Income Tax and Offer Duel. They share one convention — signed money amounts, a nominal annual rate and a payment frequency — and one job: show the arithmetic that ties present values, future values, equal payments and uneven cash flows together. TVM is the general five-register form; the other panels are the same equation in friendlier shapes.

Updated 2026-10-01Reviewed by CalcX Editorial Team6 sources5 min read

How to use the workbench

Pick a panel./finance/financial opens on TVM; the tab row switches to any of the nine, and each panel also has a direct sub-route (for example /finance/financial/compound, /finance/financial/loan, /finance/financial/npv-irr).
Fill the known registers.TVM takes N (periods), I/Y (annual rate in percent), PV, PMT and FV, plus P/Y and payment timing; outflows are negative and inflows positive, so a loan is a positive PV against negative payments. The other panels ask for principal, rate, years, contribution or cash flows.
Solve the missing number.Every TVM field has its own Solve button; the compound panel solves the monthly contribution for a target future value; the loan panel solves the principal or the term for a target payment. Compound, loan, NPV/IRR, ROI and budget readouts recompute as you type.
Read down the page.Result cards carry the headline figure and metrics; the notes explain the arithmetic, and loan and savings panels export CSV or calendar files.

Fixed inputs, exact readouts

Defaults become fixed hypothetical inputs here; re-enter them to reproduce every figure.

Panel	Inputs	Displayed readouts
TVM	N = 360, I/Y = 4.5, PV = 300,000, FV = 0, P/Y = 12, end of period	PMT -1,520.06, effective annual rate 4.5940%, APR round trip 4.5000%
Compound Interest	10,000 at 5%, 10 years, 12 compounds a year	future value 16,470.09, total interest 6,470.09; compounding once a year gives 16,288.95
Loan	300,000 at 4.5% over 30 years, equal payment	monthly payment 1,520.06, total paid 547,220.13, total interest 247,220.13
NPV / IRR	-100,000 then 30,000 / 35,000 / 40,000 / 45,000, at 10% per period	NPV 16,986.54, IRR 17.09%, rule of 72 7.2 periods
ROI	final value 15,000 against a cost of 10,000	ROI 50.00%, net gain 5,000.00
Budget	monthly income 10,000	needs 5,000.00, wants 3,000.00, savings 2,000.00

One equation, rearranged

Every panel is the same balance equation: PV + PMT × k × (1 − (1 + i)⁻ⁿ) / i + FV × (1 + i)⁻ⁿ = 0, where i is the nominal annual rate divided by P/Y and k is 1 for end-of-period payments or 1 + i for payments at the beginning. Compound interest sets PMT to zero and grows principal plus contributions; the loan panel sets FV to zero and reads PMT back; NPV discounts each cash flow at (1 + r)^t; IRR finds the rate that zeroes that sum; ROI is (final − cost) / cost; budget applies a 50/30/20 split.

Assumptions and limits

Signed money, nominal rates.: Outflows are negative and inflows positive; a rate is a nominal annual figure divided by the payment frequency. Loans round the term to whole months (1.7 years becomes 20), and contributions are credited at period end, so with annual compounding a year of monthly contributions earns nothing that year.
Arithmetic, not a forecast.: Defaults and examples are illustrative inputs, not market data. Changing one number changes every readout; display rounding means a total can differ by a few cents from a hand sum of rounded rows.
What it does not do.: This page is educational: it supplies no rates or market data, forecasts nothing, and recommends no product, provider or institution. It offers general information and scenario estimates, not investment, tax, legal or other professional advice. Series-level statistics belong to the Portfolio Lab; a single typed expression belongs to the scientific calculator.

Rates are per-period quantities

A rate typed here is nominal, and the TVM panel shows what that means: 4.5% with P/Y = 12 is 0.375% per month, and the effective annual rate card prints 4.5940% — the same input would read 4.5000% only under annual compounding. The compound panel reproduces the gap: 5% compounded 12 times a year is an effective 5.1162%, and on 10,000 over 10 years the 12-times-a-year version is worth 181.15 more (16,470.09 against 16,288.95). Nothing flags a rate entered on the wrong basis; the payment that comes back is simply a different plausible number.

Where it fits

Checking a repayment plan

The loan panel turns a principal, rate and term into a payment, totals and an exportable schedule. 300,000 at 4.5% over 30 years is 360 payments of 1,520.06 — 547,220.13 paid in total, 247,220.13 of it interest. Equal principal instead starts at 1,958.33, ends at 836.46, and pays 203,062.50 of interest.

Sizing a savings plan

10,000 plus 500 a month at 5% compounded 12 times a year reaches 94,111.23 after ten years, from 70,000.00 paid in, and a 1,000,000 target asks for 6,333.82 a month. The prepayment panel replays a schedule with an extra payment and reports the interest saved.

Reading a cash-flow series

A -100,000 outflow followed by 30,000, 35,000, 40,000 and 45,000 is worth 16,986.54 at 10% per period and carries a single IRR of 17.09%. When the signs change more than once the IRR is not unique: -100, 230, -132 returns 10.00% and 20.00%, and the panel lists both; NPV stays single-valued.

References

Wikipedia, Time value of money, en.wikipedia.org （访问日期：2026-10-01）— present value and discounting.
Wikipedia, Compound interest, en.wikipedia.org （访问日期：2026-10-01）— compounding frequencies and nominal-to-effective conversion.
Wikipedia, Effective interest rate, en.wikipedia.org （访问日期：2026-10-01）— the EAR formula and the 5% monthly example.
Wikipedia, Net present value, en.wikipedia.org （访问日期：2026-10-01）— discounted cash-flow valuation.
Wikipedia, Internal rate of return, en.wikipedia.org （访问日期：2026-10-01）— the IRR definition and the multiple-root problem.
Wikipedia, Amortizing loan, en.wikipedia.org （访问日期：2026-10-01）— level-payment formulas and schedules.