Shopping & Tax
Percentage Calculator
Calculate percentages, percentage change, difference and add/subtract in one page.
Open calculator →Accurate calculations made simple
Free Business, Marketing & Finance Calculators
Use free online calculators for percentages, discounts, profit margin, ROI, ROAS, compound interest, sales tax, VAT, income and business decisions.
Annual Income Calculator$6,850
Profit Margin Calculator28.4%
ROI14.7%
Popular calculators
The tools people reach for most often — percentages, discounts, margins, interest and tax.
Shopping & Tax
Discount Calculator
Calculate sale price, savings, stacked discounts and effective discount percentage.
Open calculator →Finance
Compound Interest Calculator
Calculate compound interest, future value and contributions with a yearly breakdown.
Open calculator →Business
Profit Margin Calculator
Find gross, operating or net margin from revenue and cost figures.
Open calculator →Shopping & Tax
Sales Tax Calculator
Add or remove sales tax using any custom rate, with quantity support.
Open calculator →Marketing
ROAS Calculator
Measure revenue generated for each unit of advertising spend.
Open calculator →Browse by category
Popular calculation guides
Go beyond the result with formulas, worked examples and interpretation guidance.
How to Calculate Profit Margin
Choose a consistent cost definition and separate margin from markup.
Markup vs Margin
See why the same profit produces different percentages under different denominators.
How to Calculate Sales Tax
Add tax to a pre-tax price and reverse it correctly from an inclusive total.
How to Calculate ROAS
Measure attributed revenue per unit of ad spend without confusing ROAS with profit.
What Is a Good ROAS?
Build a target from margin, variable costs and the profit you want to preserve.
ROI vs ROAS
Use the right metric for advertising efficiency versus broader investment return.
Why use CalcMetrio
Free to use
Every calculator is available at no cost, with no account or subscription required.
Private calculations
Calculator inputs are processed locally in your browser. Hosting logs and any enabled advertising services are handled separately; see our Privacy Policy.
Clear formulas
Each calculator shows the formula and a worked example so you can check the result by hand.
Built for speed
Static HTML and small browser scripts keep pages fast on desktop and mobile connections.
Understanding the numbers behind your decisions
CalcMetrio is a growing library of single-purpose calculators for everyday arithmetic in business, marketing, finance, shopping and tax. Each tool states the formula it uses and gives a worked example so the answer can be reproduced independently.
How our calculators are verified
Formulas are checked against manually calculated examples, ordinary values, zero values, decimals and boundary cases. Where a metric has more than one common convention, the page explains which definition is used.
Why important decisions still need verification
A calculator reflects only its inputs. Tax treatment, accounting standards, platform attribution, lender terms and local regulation can change the answer. Treat outputs as estimates and confirm consequential decisions with an appropriate qualified professional.
Frequently asked questions
Are CalcMetrio calculators free?
Yes. The calculators can be used without an account or subscription.
Are my calculator inputs sent to a server?
Core calculations run in your browser. CalcMetrio does not need your entered figures to calculate the result.
Which currencies can I use?
Monetary calculators support several display currencies, including USD, AED, EUR and GBP. Use one currency consistently within a calculation.
Can calculator results replace professional advice?
No. Results are estimates for general information. Verify consequential financial, tax, legal or accounting decisions with the appropriate professional or authority.