Guides
PDF tools
How to Reduce PDF File SizeHow to Sign a PDFHow to Merge PDF FilesHow to Convert JPG to PDFHow to Convert a PDF to JPGHow to Split a PDF or Extract PagesHow to Rotate a PDF PermanentlyHow to Add Page Numbers to a PDFHow to Watermark a PDFHow to Remove a Password From a PDFHow to Password Protect a PDFHow to Fill In a PDF FormHow to Convert a PDF to WordHow to Count the Words in a PDFHow to Compare Two PDFs
Image tools
How to Open HEIC Files on WindowsHow to Remove Location Data from PhotosHow to Make a Wi-Fi QR CodePNG vs JPG vs WebP: Which Image Format to UseHow to Copy Text from an ImageHow to Convert HEIC to JPG on a MacHow to Convert WebP to JPGHow to Reduce Image File SizeHow to Scan a QR Code from a Screenshot or ImageHow to Compress a Photo to 20 KB (or Any Size)How to Remove the Background From a PhotoHow to Blur a Face in a PhotoImage Sizes for YouTube and InstagramHow to Make a Photo CollageHow to Make ASCII Art From a Photo
Video and audio tools
How to Extract Audio from a VideoHow to Convert a Video to GIFHow to Convert WAV to MP3How to Record Your ScreenHow to Make a Ringtone for iPhoneHow to Compress a Video to Send ItWAV vs MP3: Bitrate and File SizeMP4 vs MOV vs WebM: Which Video Format to UseHow to Make a Video Small Enough to Send
Unit converters
How to Convert Celsius to FahrenheitGB vs GiB: Why Your Drive Shows Less SpaceHow to Convert Cups to GramsUS vs UK Gallons, Pints and Fluid OuncesHow to Convert Pounds and Ounces to Grams and KilogramsHow to Convert Feet and Inches to Centimeters
Calculators
How to Calculate PercentagesHow to Calculate the Number of Days Between Two DatesHow to Calculate Your BMIHow to Calculate a Mortgage PaymentHow to Schedule a Meeting Across Time ZonesHow to Calculate Your GPAHow to Calculate a TipStandard Deviation vs Standard ErrorHow to Calculate a Weighted AverageWhat Grade Do I Need on the Final?How to Add FractionsHow to Solve a Quadratic EquationHow to Run a T-TestHow to Read Japanese Era DatesKorean Age ExplainedStatistics for biology: study guideDescriptive statistics: study guideConfidence intervals: study guideInterest and loans: study guide
Text tools
How to Compare Two Text FilesHow to Count Words in a DocumentHow to Remove Line Breaks From TextHow Many Pages Is 1,000 Words?How to Use Title CaseHow Fancy Text Works
Timers and random tools
How the Pomodoro Technique WorksHow to Pick a Random Winner FairlyDice Probability: The Odds of Every Roll
Device tests
How to Test Your MicrophoneHow to Check a Screen for Dead PixelsHow to Type FasterHow to Test Your WebcamHow to Test a KeyboardHow to Test Your Speakers
Games
Minesweeper Strategy: Patterns and TipsSudoku Strategies for BeginnersHow to Win at 2048Solitaire Strategy: How to Win More GamesWord Guess Strategy: How to Solve in Fewer GuessesHow to Solve Nonograms
DNA and protein sequence tools
How to Reverse Complement a DNA SequenceHow to Translate DNA to ProteinHow to Convert GenBank to FASTAHow to Find Restriction Sites in a DNA SequenceHow to Align Two DNA or Protein SequencesHow to Design and Check PCR PrimersDNA and Protein Sequence Statistics ExplainedHow to Read a GenBank FileHow to Read a Plasmid MapHow to Design a CRISPR Guide RNAHow to Cite Online Tools and Software in a PaperWhat Is the Isoelectric Point of a Protein?How to Read a Codon Usage TableHow to Find CpG Islands in a DNA SequenceHow to Find Open Reading Frames (ORFs)How to Calculate GC ContentHow to Calculate Percent Identity and SimilarityDNA and molecular biology: study guideBiological macromolecules: study guide
Chemistry calculators
How to Calculate Molar MassHow to Balance a Chemical EquationHow to Make a Solution of a Given MolarityHow to Calculate a Dilution (C1V1 = C2V2)How to Calculate pHHow to Calculate Half-LifeThe Ideal Gas Law ExplainedHow to Do a Serial DilutionHow to Find the Limiting ReagentHow to Find an Empirical FormulaMolarity vs Molality vs NormalityHow to Convert mg/mL to Molarity and BackHow to Calculate a Dilution FactorHow to Convert Grams to MolesHow to Use q = mcΔTHow to Use the Nernst EquationHow to Calculate OsmolarityMoles and stoichiometry: study guideSolutions and concentration: study guideGases: study guideThermochemistry: study guideSpectroscopy: study guideAcids, bases and buffers: study guideElectrochemistry: study guideReactions and mechanisms: study guidePolymers and biomolecules: study guideFormulas and stoichiometry: study guideThermodynamics: study guide
Biology lab calculators
How to Calculate DNA Concentration From A260How to Calculate Insert Amount for a LigationHow to Convert RPM to g (RCF)How to Count Cells With a HemocytometerHow to Use a Punnett SquareHow to Calculate qPCR Fold Change With ΔΔCtHow to Calculate Primer Tm and Annealing TemperatureHow to Measure Protein Concentration at A280How to Resuspend Primers and OligosHow to Calculate MOI for Viral InfectionHow to Make a Standard CurveHow to Calculate an IC50How to Make a PCR Master MixHow to Make an Agarose GelHow to Make an SDS-PAGE GelHow to Make a Stock SolutionHow to Calculate Cell Seeding DensityHow to Calculate Cell Doubling TimeHow to Calculate Transformation EfficiencyHow to Calculate Cell ViabilityHow to Calculate DNA Copy NumberHow to Design qPCR PrimersHow to Reconstitute a Lyophilized Protein or PeptideGenetics and inheritance: study guidePatterns of inheritance: study guidePopulations and growth: study guideMolecular biology lab calculations: study guide
Finance calculators
How to Make a Budget With the 50/30/20 RuleDebt Snowball vs Debt AvalancheHow Much Do I Need to Retire?How to Convert Salary to Hourly PayProfit Margin vs MarkupHow to Calculate VAT and Sales TaxHow to Make an InvoiceHow Much House Can I Afford?How Loan Amortization WorksROI vs CAGR: How to Measure an Investment's ReturnHow Inflation Shrinks Your SavingsShould I Rent or Buy a Home?How to Set a Freelance Hourly RateHow to Split Tips FairlyGerman Tax Classes (Steuerklassen) ExplainedHow GST Works in IndiaInvestment returns: study guide
Engineering calculators
How to Read Resistor Color CodesHow to Choose a Resistor for an LEDHow to Calculate Voltage Drop in a CableHow Much Concrete Do I Need?How Much Paint Do I Need?How to Calculate a SubnetSignificant Figures RulesHow a Voltage Divider Works555 Timer CalculationsHow to Calculate Roof PitchHow to Calculate Board FeetHow to Calculate Aspect RatioHow to Use Ohm's LawHow to Calculate TorqueAWG vs mm²: Wire Sizes ExplainedMetric vs Imperial Screw ThreadsHow to Calculate Cable SizeHow to Calculate Cutting Speed and RPMHow to Calculate Roof AreaPPI vs DPIHow to Convert kW to AmpsHow to Plan StairsHow Many Tiles Do I Need?How Much Gravel Do I Need?How Much Wallpaper Do I Need?What Is an RC Time Constant?How Many Solar Panels Do I Need?Engineering Notation vs Scientific NotationHow Much Concrete Does a Mixer Hold?How to Calculate Pipe Flow Rate and Pressure DropNumber systems and data: study guideData size and networks: study guideForces and Newton’s laws: study guideRotation and torque: study guideStress, strain and structures: study guideElectric circuits: study guideAC circuits: study guide
Developer tools
How to Verify a File Checksum (SHA-256)How to Create a Strong PasswordWhat Is a Unix Timestamp?What Is a Hash? MD5, SHA-1 and SHA-256 ExplainedWhat Is a Cron Expression?Regex Basics: A Beginner's Guide With ExamplesHEX vs RGB vs HSL ColorsWhat Is Base64 (and URL Encoding)?
Science simulations
Snell's Law, Refraction and Total Internal ReflectionAtomic Orbitals Explained: s, p, d and fHow Gel Electrophoresis Works and How to Read a DNA GelMoon Phases, Tides and Eclipses ExplainedThe Binomial Distribution, the Bell Curve and the Galton BoardSeries and Parallel Circuits ExplainedHow Buffers Work: Henderson-Hasselbalch and Buffer CapacityMitosis vs Meiosis: the Phases, Crossing Over and NondisjunctionHow the Greenhouse Effect WorksFourier Series Explained: Building Waves From SinesBernoulli's Principle Explained: Continuity, Venturi Meters and Pipe FrictionHow Electromagnetic Induction Works: Faraday's Law, Lenz's Law, Generators and TransformersHow Chromatography Works: Rf Values, Columns and ResolutionThe Beer-Lambert Law Explained: Absorbance, Spectrophotometers and Standard CurvesHow Protein Synthesis Works: Transcription, Translation and MutationsPhotosynthesis and Limiting Factors: Light, Carbon Dioxide and TemperaturePredator and Prey Cycles: The Lotka–Volterra Equations ExplainedSIR and SEIR Epidemic Models: R₀, Herd Immunity and Flattening the CurveThe Life Cycle of a Star and the Hertzsprung–Russell DiagramCrystal Lattices, Unit Cells and X-Ray DiffractionCell structure and organelles: study guideMembranes and transport: study guideCells and transport: study guideRespiration and photosynthesis: study guideCell cycle and meiosis: study guideGene expression and protein synthesis: study guideEvolution and natural selection: study guideEcology and energy flow: study guideHuman physiology: study guideNerves and muscles: study guidePlant biology: study guideImmunity and epidemiology: study guideEnzymes and proteins: study guideBiotechnology and molecular methods: study guideMicrobial growth and counting: study guideAtomic structure and light: study guideReaction kinetics: study guideChemical equilibrium: study guideFree energy and spontaneity: study guideProbability and distributions: study guideOrbits and starlight: study guideEarthquakes, plates and dating: study guideNomenclature (naming compounds): study guideFunctional groups: study guideStructure and bonding: study guideHydrocarbons: alkanes, alkenes and alkynes: study guideAlcohols, phenols and ethers: study guideAldehydes and ketones: study guideCarboxylic acids and derivatives: study guideAmines: study guideAromatic compounds: study guideStereochemistry: study guideSubstitution, elimination and carbocations: study guidePhysical properties and acidity: study guideNMR and IR spectroscopy: study guideLaboratory techniques: study guideKinematics: study guideElectromagnetic induction: study guideModern physics: study guideProjectile motion: study guideWork, energy and power: study guideMomentum and collisions: study guideCircular motion and gravitation: study guideOscillations: study guideFluids: study guideWaves and sound: study guideOptics: study guideElectrostatics: study guideMagnetism: study guide