A practical workflow
Enter known values, calculate, review the visible formula, then copy the result before leaving the page.
Everyday & Business Calculators
General-purpose calculators for shopping, restaurants, work, marketing and small-business planning. The formulas are visible, and entered values remain in your browser.
🔒 Processing happens locally in your browser. Files and entered values are not uploaded.
Tools in this toolkit
23 tools Age Calculator Calculate your exact age in years, months, days — even hours, minutes and seconds. Next-birthday countdown included. Free, instant, private. Percentage Calculator Three percentage calculators in one: X% of a number, one number as a percent of another, and percentage increase or decrease. Instant, client-side. GPA Calculator Calculate your semester or cumulative GPA on the 4.0 scale. Letter or percentage grades, weighted by credits — instant and private. Reading Time Calculator Convert word counts into reading and speaking time. Adjustable speed, sentences and paragraphs included — instant and private. Invoice Generator Create a professional invoice with line items, tax and totals, then download it as a clean PDF. No signup, no watermark — built in your browser. Percentage Change Calculator Use this percentage change calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Percentage Increase Calculator Use this percentage increase calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Discount Calculator Use this discount calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Tip Calculator Use this tip calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Margin Calculator Calculate gross profit and margin from revenue and cost. Compare margin with markup using a clear 80-cost, 100-revenue example. Markup Calculator Use this markup calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Profit Calculator Use this profit calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Break-even Calculator Find break-even units from fixed costs, price and variable cost. See a 100-unit example and why non-positive contribution has no positive break-even. ROI Calculator Use this roi calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. ROAS Calculator Calculate revenue divided by ad spend, see what a 3× ROAS means, and understand why attributed revenue is different from profit. CPA Calculator Use this cpa calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. CAC Calculator Use this cac calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Conversion Rate Calculator Use this conversion rate calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. CPM Calculator Use this cpm calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Hourly to Annual Salary Calculator Use this hourly to annual salary calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Annual Salary to Hourly Calculator Use this annual salary to hourly calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Ratio Calculator Use this ratio calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded. Weighted Average Calculator Use this weighted average calculator with a clear formula, worked example and instant results. Values stay in your browser and are not uploaded.
When this toolkit helps
Covers shopping, restaurant tips, salaries, margins, advertising metrics and small-business planning without sending entered amounts to analytics.
Before you use the result
These are arithmetic aids, not tax, investment, medical or legal advice. Validate assumptions and local rules before making a decision.
Start with a focused tool
Start with percentage calculations, then choose the focused business or salary calculator that matches the question.
Practical guides
- Free Freelance Invoice Template + PDF Generator
What a professional freelance invoice must contain, the mistakes that delay payment, and a free browser tool that generates a clean PDF invoice with no signup.
- How Long Is My Speech? Convert Words to Minutes
How to convert word count into speech length: the 130 words-per-minute rule, real pacing benchmarks by genre, and a calculator that does the math for any text.
- How to Calculate GPA on a 4.0 Scale
A clear walkthrough of GPA math: the 4.0 scale, credit weighting, semester vs cumulative GPA, and how percentage grades convert — plus a calculator that does it live.
- Margin, ROAS and Break-Even: Read the Denominator First
Compare three business ratios with worked arithmetic: 20% margin, 3× ROAS and 100 break-even units, including zero-denominator limits.
Private by design
Process files and create static codes on your device. No file uploads or account required.