Finance & Everyday Math Calculators

Work back to the original value — and see why adding the percentage on again is wrong.

Tip, total, and the per-person split — pick 15/18/20/25% or enter your own.

The sale price after a percentage off — or the ticket price, working back from what you paid.

Add sales tax to a price, or back it out of a tax-included total to find the pre-tax amount.

Price, profit, markup, and margin from your cost — set the price by markup %, margin %, or a target price.

Convert an hourly rate to annual, monthly, and weekly pay — or a salary back to an hourly rate.

Split a group bill evenly with tip — the per-person number front and center.

Interest and total from principal, rate, and time — simple interest, not compound.

Growth with interest on interest — principal, rate, time, compounding frequency, and optional monthly deposits.

Monthly payment, total interest, and total paid on any fixed-rate loan — auto, personal, or student.

Monthly auto payment from price, down payment, trade-in, rate, term, and tax — with the amount financed.

How much to save each month to hit a goal — or how long a fixed deposit takes — with compound growth.

Return on investment and net profit — plus the annualized rate when you add a holding period.

What inflation does to buying power — and the future dollars needed to match today’s value.

A rough take-home estimate per paycheck from gross salary, pay frequency, and a combined deduction rate.

The units and revenue to cover your costs — fixed costs over the contribution margin per unit.

Monthly payment, PMI drop-off, and 5/1 ARM cap math — down to the dollar.

How long a balance really takes to clear, and what the minimum payment costs you.

The full payment table, and what one extra payment a year actually removes.

Snowball against avalanche on your own debts, with the real cost of each order.

The monthly comparison and the break-even year, with the costs people forget included.

Price per unit across different package sizes, so the bigger box is not assumed cheaper.

Compound annual growth rate from a start value, an end value and a number of years.

The 50/30/20 split on your own take-home pay, with the categories spelled out.