Calculators — 21 Free Online Tools
21 free online calculators. No signup required.
Free online calculators for everyday math: basic arithmetic, BMI, percentage, age, dates, and tips. No signup, no ads, browser-based.
Need a JSON formatter online or an image compressor free? DevTools Hub has both, plus 281 free online developer tools that run entirely in your browser. Calculators are free online developer tools you can use instantly — no signup, no upload, 100% private. Popular free tools in this category include a free online calculator, a BMI calculator, an age calculator, or a percentage calculator — all free to use online, no signup required. DevTools Hub is a collection of 281 free online developer tools that run entirely in your browser — no signup, no upload, no watermark. Popular tools across the whole site include a free JSON formatter online, a free image compressor free, a free online video compressor, and a free online calculator.
Age Calculator - Years, Months, Days & Birthday
Free age calculator. Calculate your exact age in years, months, days, hours. See next birthday countdown and milestone dates. No signup required.
Body Fat Calculator - Navy, YMCA & BMI Free
Free body fat calculator: US Navy, YMCA, BMI and Jackson-Pollock methods. Fat mass, lean mass, healthy ranges and target weight. Private, no signup.
Calorie Calculator - Free TDEE BMR & Macro Calculator
Free calorie calculator. Calculate your TDEE, BMR, and optimal macros for weight loss, maintenance, or muscle gain. Mifflin-St Jeor equation, no signup, 100% private. AI cannot compute accurate metabolic formulas.
Date Calculator - Days Between & Date Arithmetic
Free online date calculator. Calculate days between dates, add subtract days/weeks/months/years, count business days. 100% private browser processing. AI hallucinates date math - we deliver deterministic results.
Days Until Calculator - Countdown to Any Date
Free days until calculator. Countdown to any date: Christmas, birthday, holiday, or event. See how many days, hours, minutes left. No signup required.
Dog Age Calculator - Dog Years to Human Years
Free dog age calculator. Convert dog years to human years with size-adjusted AVMA formulas and the UCSD epigenetic clock. Breed presets, life stages, chart. No signup, 100% private.
Due Date Calculator - Pregnancy & Ovulation Calendar
Free due date calculator using LMP, conception, and IVF methods. Includes ovulation calculator and period predictor. 100% private, no signup, no tracking. AI cannot compute personalized due dates - we use deterministic formulas.
Fraction Calculator - Add Subtract Multiply Divide Fractions
Free fraction calculator. Add, subtract, multiply, divide fractions. Simplify, convert mixed/improper, compare. Step-by-step, 100% private browser. AI cannot do fraction math - we do.
Free BMI Calculator - Body Mass Index Checker
Free BMI calculator to check your body mass index. Supports metric and imperial units. Instant results with health category classification. No signup required.
Free Online Calculator - Math Problem Solver
Free online calculator with scientific functions, unit conversion, loan calculator, and BMI calculator. No signup required, works in any browser.
Free Tip Calculator - Quick & Easy Restaurant Tip Tool
Free tip calculator for restaurants. Calculate tip amount, split bills, and see per-person cost. Works offline, no signup required. Instant results.
Grade Calculator - Weighted Average, Final Exam & GPA
Free grade calculator. Calculate weighted average grades, what you need on the final exam, and GPA. No signup, 100% private browser tool. AI gets grade math wrong - we don't.
P-Value Calculator - Hypothesis Test & Z, T, Chi-Square
Free p-value calculator. Run z-test, t-test (one/two-sample/paired), chi-square, linear regression and confidence interval. Exact p-values, step-by-step. No signup, 100% private.
Percentage Calculator - Find %, Increase, Decrease & Difference
Free percentage calculator online. Calculate X% of Y, increase/decrease, reverse percentage, and add/subtract percent. Instant results, no signup.
Poker Odds Calculator - Texas Hold'em Equity
Free poker odds calculator. Exact hand-vs-hand equity by full enumeration, not Monte Carlo. Board cards, up to 3 players, call/fold helper. No signup.
Running Pace Calculator - Pace, Time & Distance Tool
Free running pace calculator. Calculate pace, time, or distance for any race. Generate split times, predict race times with Riegel formula, convert pace units. No signup, 100% private browser tool. AI cannot calculate running paces reliably.
Salary Calculator - Free Hourly to Annual Pay Converter
Free salary calculator to convert hourly, annual, monthly, biweekly, and weekly pay instantly. Calculate overtime and unpaid time adjustments. No signup, 100% private browser tool. AI hallucinates salary math - we deliver precise results.
Sleep Calculator - Bedtime & Wake Up Time Optimizer
Free sleep calculator based on 90-minute cycles. Find your optimal bedtime or wake-up time to feel refreshed. Age-adjusted recommendations for children, teens, adults, and seniors. No signup, 100% private. AI cannot calculate personalized sleep cycles - we use deterministic cycle math.
Speech Time Calculator - Words to Minutes & Speaking Time
Free speech time calculator. Convert words to minutes and seconds at standard speaking rates (100-238 wpm). Paste text, set WPM, add pause buffer. No signup. AI hallucinates speech times.
Statistics Calculator - Mean Median Standard Deviation
Free statistics calculator. Compute mean, median, mode, standard deviation, variance, quartiles and z-scores step by step. No signup, 100% private.
Work Hours Calculator - Free Time Card & Timesheet
Free work hours calculator with overtime, break deductions & payroll. Supports 12h/24h time. No signup. AI cannot do precise time math - we do.
Frequently Asked Questions
4 Q&AHow many free calculators are available?
There are 12 free online calculators: age, BMI, basic, calorie, date, days-until, fraction, grade, percentage, speech-time, tip, and work-hours. All run locally in your browser with no signup, no ads, and no data transmission.Are the calculator results accurate for medical, financial, or legal decisions?
Results are produced by standard, well-tested formulas (BMI = kg/m^2, age in calendar units, percentage = part/whole * 100, etc.) and are appropriate for everyday use. They are not a substitute for advice from a licensed medical, financial, or legal professional.Do the calculators send my numbers to a server?
No. Every calculation runs entirely in your browser using JavaScript. Nothing is uploaded, logged, or stored. Closing the tab clears all input.Can I use these on a phone or tablet?
Yes. All 12 calculators are touch-friendly, use a single-column layout on small screens, and work offline once the page has loaded once.How to Use These Calculator Tools
guideEvery calculator tool below runs entirely in your browser — no signup, no upload, no watermark. To find a specific tool, type a name, keyword, or scenario into the search box and the list filters instantly. Popular calculator tools are linked in the summary at the top; click any card or link to open the tool and follow the on-screen instructions. Hover any tool card to read its full description, then click its name or button to open it.