ProblemSolverTools — 147 free problem-solving tools that just work.
ProblemSolverTools at problemsolvertools.online brings you 147 free tools for the problems people actually search for — mortgage and BMI calculators, PDF merging, image compression, JSON formatting and more. Each one runs entirely in your browser.
Finance & Money
14 toolsMortgage Calculator
Monthly payment, total interest, payoff date and a full amortisation schedule — with tax, insurance and PMI kept separate, the way Calculator.net does it.
Finance & MoneyLoan / EMI Calculator
Monthly EMI for a personal, car or home loan, with total interest and an amortisation schedule.
Finance & MoneyAuto Loan Calculator
Compare dealer finance offers including trade-in value and sales tax.
Finance & MoneyCompound Interest Calculator
See savings or investments grow with regular monthly deposits, year by year.
Finance & MoneySimple Interest Calculator
Quick interest on a fixed deposit or an informal loan.
Finance & MoneyRetirement & Savings Goal Calculator
How much you must save each month to reach a target by a set date.
Finance & MoneyInvestment / ROI Calculator
Judge whether an investment was worth it: ROI %, net profit and annualised return (CAGR).
Finance & MoneySIP / Recurring Investment Calculator
Project monthly mutual-fund-style investing (SIP), popular in India.
Finance & MoneySalary Converter (Hourly ↔ Annual)
Convert a job offer between hourly pay and annual salary, with daily, weekly and monthly equivalents.
Finance & MoneySales Tax / VAT Calculator
Add tax to a net price, or strip it out of a tax-inclusive total — correctly.
Finance & MoneyTip Calculator & Bill Split
End the restaurant-table argument: tip, total and per-person split in one tap.
Finance & MoneyDiscount Calculator
Is the sale price actually good? Handles stacked discounts correctly — they multiply, they don't add.
Finance & MoneyCredit Card Payoff Calculator
See how long a balance really takes to clear — and what minimum payments cost you.
Finance & MoneyDebt-to-Income (DTI) Calculator
Check whether a lender is likely to approve you, using the ratio they actually look at.
Finance & MoneyHealth & Fitness
13 toolsBMI Calculator
Body Mass Index with the WHO/CDC adult category and the healthy weight range for your height.
Health & FitnessBMR Calculator
Basal Metabolic Rate — the calories your body burns at complete rest — via Mifflin-St Jeor.
Health & FitnessTDEE / Calorie Calculator
How many calories to eat to lose, maintain or gain weight, from your BMR and activity level.
Health & FitnessMacro Calculator
Split your daily calories into protein, carbs and fat grams for your goal.
Health & FitnessBody Fat % Calculator
US Navy circumference method — because BMI can't tell muscle from fat.
Health & FitnessIdeal Weight Calculator
A realistic target range from four published formulas — not one falsely precise number.
Health & FitnessPregnancy Due Date Calculator
Estimated due date from your last period or conception date, using Naegele's rule (ACOG).
Health & FitnessOvulation & Fertile Window Calculator
Your likely ovulation day and fertile window from your cycle dates.
Health & FitnessPeriod Calculator
Predict your next three periods and likely ovulation days for planning.
Health & FitnessRunning Pace Calculator
Enter any two of time, distance and pace — get the third, plus kilometre splits.
Health & FitnessHeart Rate Zone Calculator
Training zones 1–5 by % of max heart rate and by the Karvonen (heart-rate reserve) method.
Health & FitnessWater Intake Calculator
A daily hydration target from your weight and activity.
Health & FitnessSleep Calculator
Wake up between 90-minute sleep cycles instead of in the middle of one.
Health & FitnessMath & Education
14 toolsPercentage Calculator
The web's most-searched calculator (2.24M searches/month in SEMrush data for one competitor alone): % of a number, what %, and % change.
Math & EducationScientific Calculator
A real calculator when you don't have one: trig, logs, powers, roots and constants, with history.
Math & EducationFraction Calculator
Add, subtract, multiply and divide fractions and mixed numbers, fully simplified.
Math & EducationGPA Calculator
Semester and cumulative GPA on the standard 4.0 scale, weighted by credit hours.
Math & EducationFinal Grade Calculator
What do you need on the final exam to get the grade you want?
Math & EducationGrade / Test Score Calculator
Convert marks into a percentage and letter grade instantly.
Math & EducationMean, Median, Mode & Range
Paste a list of numbers for an instant statistics summary.
Math & EducationStandard Deviation Calculator
Spread of a dataset, with both sample and population standard deviation.
Math & EducationRatio & Proportion Calculator
Solve a/b = c/x, simplify ratios, and scale recipes, maps and mixtures.
Math & EducationQuadratic Equation Solver
Solve ax² + bx + c = 0 with real or complex roots, discriminant and vertex.
Math & EducationPythagorean Theorem Calculator
Find the missing side of a right triangle.
Math & EducationArea Calculator
Areas of common shapes, with the formula for each — a top school-search topic (1.22M searches/month in SEMrush data).
Math & EducationVolume Calculator
Volumes of cubes, boxes, cylinders, spheres, cones and pyramids.
Math & EducationSlope & Line Calculator
Slope, equation, midpoint and distance between two points.
Math & EducationText, Writing & SEO
13 toolsWord Counter
Words, characters, sentences, paragraphs and reading time — counted live as you type. One of the most-used tools on every tool hub.
Text, Writing & SEOCharacter Counter
Live character counts checked against X, title-tag, meta-description, LinkedIn and other real platform limits.
Text, Writing & SEOCase Converter
Fix ALL-CAPS accidents or convert headings: upper, lower, Title, Sentence, aLtErNaTiNg, camelCase, snake_case and more.
Text, Writing & SEORemove Duplicate Lines
Clean lists, email addresses and keyword sets — duplicates gone, count shown.
Text, Writing & SEOText Diff Checker
What changed between two drafts? Line-by-line differences, highlighted.
Text, Writing & SEOReadability Calculator
Is this text too hard for its audience? Flesch Reading Ease and Flesch-Kincaid grade level.
Text, Writing & SEOReading & Speaking Time Calculator
How long an article, script or speech actually runs.
Text, Writing & SEOKeyword Density Checker
An SEO sanity check — see your top 1, 2 and 3-word phrases and their density.
Text, Writing & SEOSlug Generator
Turn a post title into a clean URL slug.
Text, Writing & SEOFind & Replace
Bulk text edits without opening a word processor — with a replacement count.
Text, Writing & SEOSort Lines / Alphabetiser
Order any list alphabetically or numerically, ascending or descending, with optional de-duplication.
Text, Writing & SEOText Reverser & Line Shuffler
Reverse characters, words or lines — or shuffle lines into a random order.
Text, Writing & SEOMeta Tag & Title Length Checker
Preview exactly how your page will look in Google results, with pixel-width measurement.
Text, Writing & SEODeveloper & Coding
13 toolsJSON Formatter & Validator
Make unreadable API JSON readable, minify it, and pinpoint syntax errors with line and position.
Developer & CodingJSON ↔ CSV Converter
Move data between APIs and spreadsheets in both directions.
Developer & CodingBase64 Encoder / Decoder
Encode text for APIs and data-URIs, or decode Base64 back — UTF-8 safe.
Developer & CodingURL Encoder / Decoder
Fix broken links and query strings with proper percent-encoding.
Developer & CodingJWT Decoder
Inspect a token's header and claims, with a live expiry countdown. Decoding is not verification — the signature is not checked.
Developer & CodingRegex Tester
Build a pattern that actually matches: live highlighting, match list and capture groups.
Developer & CodingSQL Formatter
Make generated queries reviewable: indented, with keywords upper-cased.
Developer & CodingMarkdown Editor & Preview
Write README and docs with a live preview, and export the HTML.
Developer & CodingHTML Entity Encoder / Decoder
Stop &, < and > breaking your pages — encode or decode HTML entities.
Developer & CodingUnix Timestamp Converter
What date is 1735689600? Epoch ↔ human date in UTC and your local time, plus relative time.
Developer & CodingCron Expression Explainer
When does 0 3 * * 1 actually run? Plain-English translation plus the next 5 run times.
Developer & CodingIP Subnet Calculator
Plan networks and CIDR ranges: network, broadcast, usable hosts and ranges.
Developer & CodingLorem Ipsum Generator
Placeholder copy for mock-ups — paragraphs, sentences or words, classic or hipster-free plain Latin.
Developer & CodingUnit & Data Converters
13 toolsTemperature Converter
°C ↔ °F ↔ Kelvin for weather, cooking and science — with the formula shown.
Unit & Data ConvertersNumber Base Converter
Binary, octal, decimal and hex side by side — for CS classes and developers.
Unit & Data ConvertersCooking Measurement Converter
Cups ↔ grams by ingredient — because a cup of flour is not a cup of sugar.
Unit & Data ConvertersLength Converter
cm ↔ inches, km ↔ miles, feet ↔ metres — with a full table for the value you enter.
Unit & Data ConvertersWeight Converter
kg ↔ lb ↔ oz ↔ stone for health, luggage and recipes.
Unit & Data ConvertersArea Converter
m² ↔ ft² ↔ acres ↔ hectares for property listings and land.
Unit & Data ConvertersVolume Converter
Litres ↔ gallons ↔ cups ↔ ml for recipes and fuel. US units.
Unit & Data ConvertersSpeed Converter
km/h ↔ mph ↔ m/s ↔ knots.
Unit & Data ConvertersData Storage Converter
MB ↔ GB ↔ TB with the SI (1000-based) vs IEC (1024-based) distinction made explicit.
Unit & Data ConvertersTime Unit Converter
Seconds ↔ minutes ↔ hours ↔ days ↔ weeks ↔ years.
Unit & Data ConvertersPressure Converter
bar ↔ psi ↔ atm ↔ Pa for tyres, machines and weather.
Unit & Data ConvertersEnergy Converter
Joules ↔ calories ↔ kWh ↔ BTU.
Unit & Data ConvertersPower Converter
Watts ↔ horsepower ↔ kW for engines and appliances.
Unit & Data ConvertersDate & Time
11 toolsAge Calculator
Exact age in years, months and days for forms, school and eligibility — plus total days and your next birthday.
Date & TimeDate Difference Calculator
Days between two dates for deadlines, tenures and countdowns — with a years/months/days breakdown.
Date & TimeDate Add / Subtract Calculator
'90 days from today is…' — add or subtract days, weeks, months or years.
Date & TimeBusiness Days Calculator
Working days between dates, with a configurable weekend and your own holiday list — no country's holidays are assumed for you.
Date & TimeCountdown Timer
A live countdown to any event, exam or deadline.
Date & TimeStopwatch & Timer
Timing tasks, cooking and workouts — laps included, no app install.
Date & TimeTime Zone Converter
3pm in London is what in Karachi or New York? Converted with the browser's Intl time-zone database, daylight saving included.
Date & TimeWeek Number Calculator
ISO week number and day of year for planning and reporting.
Date & TimeWork Hours / Timesheet Calculator
Weekly hours and gross pay from clock-in and clock-out times.
Date & TimePomodoro Timer
Focus sessions with automatic work/break cycles and a session counter.
Date & TimeDay-of-Week Finder
The weekday of any historical or future date — plus its zodiac sign and day-of-year.
Date & TimeEveryday Life & Home
12 toolsBill Splitter
Split a shared meal or household bill fairly, with tax and tip handled per person.
Everyday Life & HomePaint Calculator
How many litres and cans to buy — doors, windows and coats accounted for.
Everyday Life & HomeTile / Flooring Calculator
Tiles and boxes to order, including the wastage professionals always add.
Everyday Life & HomeConcrete Calculator
Volume and bag count for a slab, footing or post hole.
Everyday Life & HomeElectricity Cost Calculator
What does this appliance actually cost to run — per day, month and year?
Everyday Life & HomeFuel Cost & MPG Calculator
Budget a trip's fuel, or work out your car's real efficiency.
Everyday Life & HomeRecipe Scaler
Scale a recipe up or down — paste ingredients with quantities, get the new amounts.
Everyday Life & HomeShoe Size Converter
Buy shoes from foreign stores: US, UK, EU and foot length side by side.
Everyday Life & HomeRoman Numeral Converter
Numbers ↔ Roman numerals for dates, chapters and clock faces (1–3999).
Everyday Life & HomeUnit Price Comparison
Which pack size is actually cheaper? Compare up to four products by price per unit.
Everyday Life & HomeMulch / Gravel Calculator
Garden material volume, bag count and approximate weight for a bed or path.
Everyday Life & HomeWallpaper Calculator
Rolls needed without over-buying — pattern repeat accounted for.
Everyday Life & HomeBusiness & Marketing
11 toolsProfit Margin & Markup Calculator
Price products without losing money: margin, markup and selling price in both directions.
Business & MarketingBreak-Even Calculator
How many sales before this product or business starts making profit?
Business & MarketingInvoice Generator
A professional, printable invoice without accounting software — generated entirely in your browser.
Business & MarketingFreelance Rate Calculator
Convert a salary goal into the hourly rate you actually need to charge.
Business & MarketingCPM / CPC / CPA Calculator
Make sense of ad-platform reports: enter any values, get the rest.
Business & MarketingConversion Rate Calculator
Your conversion rate, and what small improvements are worth in revenue.
Business & MarketingYouTube / AdSense Earnings Estimator
Rough creator income expectations from views and niche RPM — labelled as the estimate it is.
Business & MarketingEmail Signature Generator
A professional email signature in minutes — copy the HTML or the rendered signature.
Business & MarketingMulti-Rate Tax Quote Calculator
Quotes and invoices where different lines carry different tax rates — done correctly, per rate.
Business & MarketingMeeting Cost Calculator
What does this meeting really cost? The number that makes people rethink recurring invites.
Business & MarketingHashtag & Caption Planner
Check a caption against each platform's limits and count its hashtags before you post.
Business & MarketingSecurity & Generators
11 toolsPassword Generator
Strong, unique passwords from your device's cryptographic random generator. Nothing is sent anywhere or stored.
Security & GeneratorsPassword Strength Checker
Is your password actually safe? Entropy, crack-time estimates and concrete fixes. Your password never leaves this page.
Security & GeneratorsQR Code Generator
QR codes for links, Wi-Fi networks and contact cards, downloadable as PNG.
Security & GeneratorsUUID Generator
Generate random (v4) or time-ordered (v7) unique IDs for development and test data.
Security & GeneratorsRandom Number Generator
Unbiased random numbers for draws, games and sampling — cryptographic RNG, not Math.random().
Security & GeneratorsRandom Picker / List Shuffler
Pick a fair winner from a list, or shuffle a list into a provably random order (Fisher–Yates with crypto RNG).
Security & GeneratorsRandom Team Generator
Split a class, squad or workshop into balanced random teams.
Security & GeneratorsDice Roller & Coin Flip
Roll any dice combination, flip coins, and see the totals — for games and probability demos.
Security & GeneratorsPIN & Passphrase Generator
Memorable-but-strong passphrases from random words, or PINs of any length.
Security & GeneratorsHash Generator (SHA-1 / SHA-256 / SHA-512)
Checksums for text using the Web Crypto API built into your browser.
Security & GeneratorsFake / Test Data Generator
Dummy names, emails and addresses for testing forms and databases. Clearly fake — never use for real accounts.
Security & GeneratorsImage & Colour
12 toolsImage Compressor
Shrink photos for upload limits and email — processed on your device, never uploaded.
Image & ColourImage Resizer
Exact pixel sizes for avatars, application forms and marketplaces.
Image & ColourImage Cropper
Centre-crop to 1:1, 16:9, 4:5, passport-style ratios and more.
Image & ColourImage Format Converter
JPG ↔ PNG ↔ WebP without installing software.
Image & ColourColour Picker & HEX ↔ RGB ↔ HSL Converter
One colour, every format a developer or designer needs — with copy buttons.
Image & ColourColour Palette Generator
A harmonious 5-colour palette from any base colour: complementary, analogous, triadic and more.
Image & ColourCSS Gradient Generator
Design a gradient visually, then copy production-ready CSS.
Image & ColourWCAG Contrast Checker
Is that text actually readable? Contrast ratio with AA/AAA pass-fail for normal and large text.
Image & ColourFavicon Generator
A full favicon set from one image or emoji: 16, 32, 180, 192 and 512 px.
Image & ColourImage to Base64
Embed small images directly in CSS or HTML as a data-URI.
Image & ColourEXIF Viewer & Remover
See the camera and GPS data hidden in a photo — and strip it before sharing. Read locally; nothing is uploaded.
Image & ColourSVG to PNG Converter
Rasterise vector logos and icons at any size.
Image & ColourPDF & Files
10 toolsMerge PDF
Combine forms, certificates and scans into one PDF — entirely in your browser. Your files never leave your device, unlike server-side tools that upload them.
PDF & FilesSplit PDF / Extract Pages
Send only the relevant pages: extract a page range into a new PDF.
PDF & FilesRotate PDF Pages
Fix scanned upside-down or sideways pages and save a corrected PDF.
PDF & FilesImages to PDF
Turn phone photos of documents into one clean PDF.
PDF & FilesPDF to Images
Render PDF pages as PNG images for slides, posts and previews.
PDF & FilesText to PDF
A clean, printable PDF document from plain text.
PDF & FilesPDF Page Counter & Info
How many pages, what size, what metadata? Read locally — the file is never uploaded.
PDF & FilesCSV Viewer & Cleaner
Preview, de-duplicate, sort and re-export a CSV without opening Excel.
PDF & FilesFile Hash Checker
Verify a download wasn't corrupted or tampered with: its SHA-256 checksum, computed locally.
PDF & FilesWord Count for Files
Count words and characters in a .txt or .md document.
PDF & FilesFree online calculators, converters and problem-solving tools
ProblemSolverTools is a free library of 147 online tools for everyday problems — no sign-up, no uploads, and every answer shows the formula behind it. Popular starting points include the Loan / EMI Calculator, the Mortgage Calculator, the BMI Calculator, the Percentage Calculator and the Compound Interest Calculator for money; the Word Counter and JSON Formatter for writing and code; and Merge PDF, the Image Compressor and the QR Code Generator for files and media.
Every tool is organised into 12 categories — finance, health, maths and education, text and SEO, developer tools, converters, date and time, everyday life, business, security and generators, image and colour, and PDF and files — so you can find a free calculator or converter in seconds with the search bar. Amounts can be formatted in USD, PKR, CAD, EUR, GBP, INR, AED, AUD and BDT, and the tools run entirely in your browser: your numbers, text and files are never uploaded to a server.
Whether you need a GPA calculator before results day, a salary converter to compare hourly and annual pay, a pregnancy due date calculator, a password generator, or a quick unit converter for length, weight and temperature, ProblemSolverTools gives you an instant, formula-checked answer on any device — phone, tablet or computer.