ToolSpotAI — Free Online Calculators & Tools

Credit Card Payoff Calculator

Calculate how long to pay off credit card debt and how much interest you will pay. Compare Debt Avalanche vs Snowball strategies for multiple cards.

Open CC Payoff

Unit Converter

Convert between units of length, weight, temperature, area, volume, and speed instantly.

Open Units

Password Generator

Generate strong, random passwords with configurable length, character types, and strength indicator. Uses Web Crypto API.

Open Password

Profit Margin Calculator

Calculate profit margin, markup percentage, and profit from cost and revenue. Three calculation modes for any business scenario.

Open Margin

Date Calculator

Find days between two dates, add or subtract years/months/weeks/days, and calculate business days.

Open Date

ROI Calculator

Calculate return on investment (ROI) and annualized ROI from investment cost, returns, and time period.

Open ROI

Tip Calculator

Calculate tips, split bills, and see per-person totals instantly. Supports custom tip %, rounding, and multiple currencies.

Open Tip

Education

GPA Calculator

Calculate your GPA on the US 4.0 scale (with +/- grades), UK percentage scale, and cumulative GPA across semesters.

Open GPA

Hash Generator (MD5/SHA)

Generate MD5, SHA-1, SHA-256, and SHA-512 hashes instantly in the browser. No data leaves your device.

Open Hash Generator

Writing

Case Converter

Convert text to UPPERCASE, lowercase, Title Case, camelCase, snake_case, kebab-case, and more — instantly.

Open Case Converter

Color Converter & Picker

Convert colours between HEX, RGB, and HSL. WCAG contrast checker, color palettes, and CSS output included.

Open Color Converter

Loan Calculator

Calculate monthly payments, total interest, and amortization schedule for auto, personal, student, or any fixed-rate loan.

Open Loan

QR Code Generator

Generate QR codes for URLs, text, email, phone numbers, and Wi-Fi networks. Download as PNG or SVG.

Open QR Code

Regex Tester

Test regular expressions with live matching, highlighting, capture groups, find & replace, and a quick reference cheat sheet.

Open Regex

Invoice Generator

Create professional invoices with line items, tax, discounts, and print/save as PDF — all in your browser, no signup needed.

Open Invoice

Income Tax Calculator

Calculate US federal income tax and UK income tax with brackets, deductions, FICA, National Insurance, and take-home pay.

Open Income Tax

Calorie & TDEE Calculator

Calculate your BMR, TDEE, and daily calorie target based on age, sex, height, weight, activity level, and fitness goal.

Open Calorie/TDEE

Retirement / 401k Calculator

Project your retirement savings with contributions, employer match, compound growth, and withdrawal planning using the 4% rule.

Open Retirement

Insurance Premium Estimator

Estimate monthly premiums for life insurance, health insurance, and auto insurance based on your profile and coverage needs.

Open Insurance

VAT / Sales Tax Calculator

Add or remove VAT/sales tax from any price. Supports UK VAT, EU rates, US state tax, India GST, and custom rates.

Open VAT/Tax

Debt-to-Income Ratio Calculator

Calculate your debt-to-income ratio and see if you qualify for mortgage loans. Includes lender guidelines for Conventional, FHA, VA, and USDA.

Open DTI Ratio

Currency Converter

Convert between 24+ world currencies with approximate mid-market rates. Quick reference tables and popular pairs.

Open Currency

Pregnancy Due Date Calculator

Calculate your estimated due date using LMP, ultrasound, or IVF transfer date. Track milestones and trimester progress.

Open Pregnancy

Time Zone Converter

Convert times between world time zones. Live clocks for major cities, add multiple zones, and plan meetings across regions.

Open Time Zone

Fuel / Gas Cost Calculator

Calculate fuel costs for any trip. Supports US MPG, UK MPG, and Metric (L/100km). Vehicle presets and round-trip option.

Open Fuel Cost

Education

Scientific Calculator

Full-featured scientific calculator with trigonometry, logarithms, powers, factorial, memory, and degree/radian modes.

Open Scientific Calc

Typing Speed Test

Test your typing speed in WPM with accuracy tracking. Timed tests from 30s to 3min. Track history and improve over time.

Open Typing Test

Writing

Text Similarity & Readability Analyzer

Local analysis: readability, vocabulary diversity, internal repetition. Compare two pasted texts for similarity—does not search the web.

Open Text analysis

Screen Resolution & Aspect Ratio Calculator

Calculate screen resolution, aspect ratio, PPI, and resize dimensions. Presets for phones, monitors, social media, and print.

Open Resolution

Loan Comparison Calculator

Compare up to 5 loans side by side. See monthly payments, total interest, total cost, and savings at a glance.

Open Loan Compare

Period Calculator

Track your menstrual cycle with a visual calendar. Predict next 6 periods, fertile windows, and ovulation days.

Open Period Calc

Ovulation Calculator

Find your most fertile days and ovulation date. Visual fertility timeline with conception probability for 3 cycles.

Open Ovulation

BMR Calculator

Calculate your Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle. See TDEE by activity level.

Open BMR

Ideal Weight Calculator

Find your ideal weight range using 5 scientific formulas (Devine, Robinson, Miller, Hamwi, BMI). Visual range bar included.

Open Ideal Weight

Auto Loan Calculator

Calculate monthly car payments, total interest, and amortization for auto loans with trade-in and sales tax.

Open Auto Loan

Paycheck Calculator

Convert hourly wage to salary or salary to hourly. Estimate take-home pay after US federal taxes.

Open Paycheck

Body Fat Calculator

Calculate body fat percentage using US Navy, BMI-based, or skinfold methods with detailed category breakdown.

Open Body Fat

Macro Calculator

Calculate daily macronutrient targets — protein, carbs, and fat — based on your goals and activity level.

Open Macros

Inflation Calculator

Calculate how inflation affects purchasing power over time. Compare buying power between years.

Open Inflation

Baby Name Generator

Explore popular baby names by gender, origin, and meaning. Save favorites and discover trending names.

Open Baby Names

SIP Calculator

Calculate SIP returns, lumpsum growth, and step-up SIP projections for systematic investment planning.

Open SIP

Image Compressor

Compress and resize images in your browser. Supports JPEG, PNG, and WebP with adjustable quality.

Open Image Compress

Markdown Editor

Write and preview Markdown in real time. Toolbar for formatting, copy as HTML, and live word count.

Open Markdown

Blood Pressure Calculator

Check blood pressure readings against AHA guidelines. Track multiple readings and find averages.

Open Blood Pressure

Legal

Personal Injury Settlement Calculator

Rough, educational estimate for special damages and pain-and-suffering multipliers—not legal advice or a prediction of your case.

Open Injury Settlement

Legal

Divorce Asset Split Calculator

Split a simple net marital pool by percentage—math only, not legal advice about what counts as marital property.

Open Divorce Split

Legal

Car Accident Compensation Calculator

Blend property damage with rough general-damages bands on economic losses—illustrative only, not an insurer’s offer.

Open Accident Claim

AI Writing Style Checker

Lightweight heuristics on sentence length, word variety, and a few overused patterns—editing help, not a courtroom AI detector.

Open Style Check

Image Prompt Builder

Assemble clear prompts for image models from subject, style, lighting, mood, and aspect ratio—no upload required.

Open Prompt Builder

Social Media Ad ROI Calculator

Compute ROAS, ROI percent, and optional CPA from spend, attributed revenue, and conversions.

Open Ad ROI

Crypto Tax Estimator

Rough reserve estimate on taxable crypto gains by region preset—never a substitute for a tax professional.

Open Crypto Tax

Student Loan Refinance Calculator

Compare monthly payment and total interest when you refinance federal or private loans—numbers only, not lender offers.

Open Refinance