39 free tools · no sign-up · runs in your browser
Free Online Calculators & Converters
Health and fitness planners, money and maths calculators with the working shown, converters and developer utilities. Clear answers, honest sources, nothing to install.
Workout Plan GeneratorA 4, 8 or 12-week plan for your goal and equipment, with guided sessions and 3D demos.Open GLP-1 Weight Loss CalculatorWhat Wegovy and Zepbound achieved in clinical trials, week by week, and a private tracker.Open Vision Board MakerA beautiful board for the year ahead, saved as a phone wallpaper or printed.Open
All tools
39 toolsHealth & fitness
Training plans, trackers and percentiles built on clinical data.
Workout Plan GeneratorA 4, 8 or 12-week plan for your goal and equipmentExercise LibraryEvery exercise by muscle, with rotatable 3D demosGuided Yoga FlowsFollow-along yoga with a 3D guide and breath-paced timerGLP-1 Weight Loss CalculatorWeek-by-week Wegovy & Zepbound forecast from the clinical trialsBMI CalculatorYour BMI and the healthy weight range for your heightGlucose to A1C ConverterAverage glucose to A1C and back, in mg/dL or mmol/LKids Growth CalculatorHeight and weight percentiles from the WHO and CDC chartsPenis Size Percentile CalculatorYour length and girth percentile from clinical dataPenis Size Percentile ChartLength, girth and volume at every percentile
Money
Mortgages, loans, savings and big purchases, with honest verdicts.
Mortgage CalculatorMonthly payment, total interest and your payoff dateCompound Interest CalculatorWatch savings grow, reach a goal, or see the cost of waitingLoan Prepayment CalculatorHow much sooner extra payments make you debt-freePrepayment vs Refinance CalculatorPay extra or refinance? A fair side-by-side verdictCar Buy vs Lease CalculatorBuy or lease, with net cost and a check of the dealer quoteSolar Panel ROI CalculatorWhen solar pays for itself, from your bill and state
Maths & school
Answers with the working shown, for homework and grades.
Percentage CalculatorPercent of, % change, difference and reverse percentagesBase ConverterBinary, octal, decimal and hex, with the working shownQuadratic Equation SolverRoots, exact forms, steps and the parabola for ax² + bx + cGrade CalculatorYour course grade from weighted assignmentsFinal Grade CalculatorThe score you need on the final to hit your targetGPA CalculatorSemester and cumulative GPA, weighted or unweightedAge CalculatorYour exact age, days lived and your next birthdayPhysics Unit ConverterForce, energy, speed and power in every common unitTurtle GraphicsLearn to code by drawing with a turtle
Write & create
Boards, notes, diagrams and colour, saved in your browser.
Developer
Quick utilities and capacity maths for engineers.
JSON ValidatorValidate and format JSON, with the error line pinpointedBase64 Encoder/DecoderEncode and decode Base64 text, files and data URIsPassword GeneratorStrong passwords and passphrases, generated on your deviceASCII TableEvery character with its decimal, hex, binary and HTML codeAPI Rate Limit CalculatorA per-client rate limit and burst, with ready-to-paste configsSystem Latency Budget CalculatorSplit a response-time target across your servicesKafka Message Size CalculatorMessage, batch, throughput and disk for a Kafka topicLLM Token Budget CalculatorMonthly cost of an AI feature across current modelsLLM Self-Hosted vs API CalculatorThe volume where self-hosting an LLM beats the APIJira Story Points CalculatorSize a story with the planning-poker scaleDORA Metrics CalculatorHow your team compares on the four DORA metrics