Free Online Math Calculators
Instant calculators for percentages, discounts, and proportions. No signup, no ads, runs in your browser. Perfect for students, shoppers, and professionals.
4
Calculators
100%
Free
0
Signup Needed
∞
Calculations
Percentage Change Calculator
How much did it go up or down?
Calculate the exact percentage increase or decrease between any two values. See whether the change is positive (growth) or negative (decline) at a glance.
Formula
((New − Old) ÷ |Old|) × 100- Track stock or portfolio growth
- Measure revenue or sales change
- Compare exam scores over time
Percentage of a Number
What is X% of Y?
Find what a specific percentage of any number is instantly. Perfect for calculating tips, taxes, discounts, commissions, and everyday budgeting.
Formula
(Percentage ÷ 100) × Number- Calculate sales tax on a purchase
- Work out a restaurant tip
- Find a commission amount
What Percentage is X of Y?
X is what percent of Y?
Determine what percentage one number is of another. Great for understanding test scores, survey results, project progress, and goal completion rates.
Formula
(X ÷ Y) × 100- Convert a test score to a percentage
- Track project completion
- Analyse survey data
Discount Calculator
Final price after a discount?
Calculate the final price of any item after a percentage discount and see exactly how much you save. Essential for smart shopping, retail planning, and promotion analysis.
Formula
Final Price = Price × (1 − Discount% ÷ 100)- Verify a sale price in-store
- Plan a promotional campaign
- Budget for purchases
Which Calculator Should I Use?
| If you need to… | Example | Use this calculator |
|---|---|---|
| Find a portion of a number | "What is 15% of $240?" | Percentage of a Number |
| Measure growth or decline | "Revenue went from $8k to $10k" | Percentage Change Calculator |
| Convert a score to a percentage | "I got 42 out of 55" | What Percentage is X of Y? |
| Find a price after a sale | "30% off a $150 jacket" | Discount Calculator |
| Calculate a tip | "15% tip on a $64 meal" | Percentage of a Number |
| Track investment return | "$1,000 grew to $1,340" | Percentage Change Calculator |
| Find what % one value is of another | "25 students passed out of 80" | What Percentage is X of Y? |
| Compare two sale offers | "20% off $90 vs 15% off $80" | Discount Calculator |
Percentage Formulas Reference
All the core formulas in one place — with worked examples.
| Calculation | Formula | Worked Example | Calculator |
|---|---|---|---|
| Percentage of a Number | (P ÷ 100) × N | 20% of 150 = 30 | Percentage of a Number |
| Percentage Change | ((New − Old) ÷ |Old|) × 100 | 80 → 100 = +25% | Percentage Change Calculator |
| X is what % of Y | (X ÷ Y) × 100 | 25 is 12.5% of 200 | What Percentage is X of Y? |
| Discount Amount | Price × (Discount% ÷ 100) | 25% off $80 = $20 off | Discount Calculator |
| Final Price After Discount | Price − Discount Amount | $80 − $20 = $60 | Discount Calculator |
| Reverse Percentage | Original = Value ÷ (P ÷ 100) | 60 is 75% of 80 | Percentage of a Number |
Why Use Texterfly Math Calculators?
Instant Results
All calculations update in real time as you type. No submit button, no loading — just the answer the moment you need it.
Private by Design
All calculations run entirely in your browser. No numbers are sent to any server, logged, or stored — ever.
Works Everywhere
Fully responsive for desktop, tablet, and mobile. No app download needed on iOS or Android.
Who Uses These Math Calculators?
Students
Check homework answers, convert test scores to percentages, and verify math for assignments quickly.
Shoppers
Verify sale prices in-store, compare discount offers, and work out how much you actually save before buying.
Professionals
Track KPI growth, calculate commission, measure budget variance, and present percentage changes in reports.
Investors
Calculate portfolio returns, track price changes, and measure growth across any time period with the Percentage Change Calculator.
Frequently Asked Questions
What math calculators does Texterfly offer?
Texterfly offers four free percentage calculators: Percentage Change, Percentage of a Number, What Percentage is X of Y, and a Discount Calculator. All are free, instant, and browser-based with no signup.
How do I calculate percentage change?
Formula: ((New Value − Old Value) ÷ |Old Value|) × 100. A positive result is an increase; negative is a decrease. Example: a price rising from $80 to $100 is a 25% increase.
How do I find a percentage of a number?
Multiply the number by the percentage and divide by 100. Example: 20% of 150 = (150 × 20) ÷ 100 = 30. The Percentage of a Number Calculator does this in one step.
How do I calculate what percentage X is of Y?
Divide X by Y and multiply by 100. Example: 25 is what % of 200? → (25 ÷ 200) × 100 = 12.5%.
How do I calculate a discount?
Discount amount = Price × (Discount% ÷ 100). Final price = Price − Discount Amount. Example: 25% off $80 → discount = $20 → final price = $60.
What is the difference between percentage change and percentage of a number?
"Percentage of a number" finds a portion of a value (e.g. "15% of 200 = 30"). "Percentage change" measures how much a value has grown or shrunk between two points (e.g. "$80 to $100 = 25% increase").
Are these calculators free?
Yes. All math calculators on Texterfly are 100% free with no hidden fees, no subscription, and no account required.
Do the calculators work on mobile?
Yes. All calculators are fully responsive and work on iOS, Android, and any desktop browser without any app download.
Is my data private?
Yes. All calculations run entirely in your browser. No data is sent to any server or stored anywhere.
Can I use these for finance and investing?
Absolutely. The Percentage Change Calculator is great for tracking stock changes, revenue growth, and portfolio performance. The Percentage of a Number Calculator handles tax, interest, and fee calculations.
What is a good discount percentage?
It depends on context. In retail, 10–20% is a standard promotion. 30–50% signals a major sale. Use the Discount Calculator to see the exact cash saving for any percentage.
How do I calculate a percentage on a regular calculator?
To find 20% of 150: press 150 × 20 ÷ 100 = 30. Or press 150 × 20% on most modern calculators. Online calculators like these are faster — just enter the two numbers.