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A network of 49 free, browser-based calculators and utilities from the same team — solar, electrical, construction, finance, developer, text, time and health tools. Every one runs in your browser, with no signup.

Solar, electrical & construction· 15

voltdropcalc.comCalculate voltage drop and the correct wire gauge for any DC or AC run across NEC, CEC, BS 7671, AS/NZS and IEC standards, so you don't lose power or overheat conductors.prosolarcalc.toolsA set of professional solar sizing and design tools for installers and serious DIY builders, covering the calculations behind planning a PV system from panels through to storage.solarbatterybankcalc.comOff-grid and backup battery-bank sizing done with real engineering — usable capacity, C-rate, voltage and chemistry — not the rules of thumb the sales tools lean on.backuppowercalc.comSize a generator or battery backup to the loads you actually need to run, with realistic runtime, fuel and surge-watt figures for outages.actonnagecalc.comWork out the air-conditioner tonnage and cooling load a room or whole home needs from area, climate, insulation and sun exposure, so you neither undersize nor overspend.constructioncalchq.comA hub of construction estimating calculators — concrete, materials, costs and quantities — built for the way contractors actually take off a job.concretematerialcalc.comIndia-focused concrete and material calculators for slabs, columns, footings and mixes, with bag counts and quantities worked out for you.roofingmaterialcalc.comEstimate roofing materials — shingles, underlayment and squares — from roof area and pitch, with a pitch helper for measuring from the ground.cubicyardage.comConcrete and bulk-material calculators that work in cubic yards for slabs, footings, columns, walls and stairs, with bag counts, ready-mix loads and a waste margin.staircalculators.netLay out stairs correctly — rise, run, stringer length and headroom — to code, with a clear diagram of every dimension.thesquarefootagecalculator.comMeasure square footage for floors, walls, rooms and land across rectangles, triangles, circles and irregular layouts, with unit conversion handled for you.boxvolumecalculator.comCalculate the volume and capacity of boxes, cartons and rectangular containers in any units, for packing, shipping and storage planning.tankvolumecalc.comFind the volume and fill level of tanks in many shapes — cylindrical, oval, rectangular and capsule, horizontal or vertical — for water, fuel and chemical storage.dimweightcalc.comCompute dimensional (volumetric) weight for FedEx, UPS, USPS and other carriers and compare it against actual weight, so you can predict shipping charges before you ship.girthcalculator.comMeasure a package's girth and combined length-plus-girth and check it against carrier oversize limits before you pay for shipping.

Finance & business· 5

totalinterestcalc.comSee the full lifetime cost of a mortgage or loan — total interest, amortization schedule and the effect of extra payments — so you know what borrowing really costs.indiaemi.comAn EMI calculator built for India covering home, car and personal loans plus credit-card EMI plans with GST, and EMI in advance versus in arrears.sipcalculatorhub.comProject SIP and mutual-fund returns for Indian investors with post-tax and inflation-adjusted figures, not just the headline compounded number.marginvsmarkup.comConvert between margin and markup and price products correctly, clearing up the common confusion between the two that quietly erodes profit.bestpercentagecalculator.netHandle every kind of everyday percentage problem — percentage of a number, change, increase, decrease and reverse percentages — in one clear tool.

Developer & web utilities· 15

jsontools.toolsFormat, validate, minify and explore JSON in your browser, with a tree viewer that makes large or messy payloads easy to read and debug.base64decode.toolsEncode text and files to Base64 or decode them back, entirely client-side, so nothing you paste ever leaves your machine.urlencodedecode.comPercent-encode and decode URLs and query strings so special characters travel safely, with full Unicode support.hashgenerator.toolsGenerate MD5, SHA-1, SHA-256 and other cryptographic hashes from text or files for checksums, integrity checks and fingerprinting.uuidcore.comGenerate UUIDs in bulk and learn how the different versions work, with copy-ready output for development and testing.regexguide.comBuild, test and understand regular expressions with live matching and a reference that explains each token in plain language.crontabsheet.comBuild cron schedules visually and read back exactly when a crontab expression will run, with a cheat sheet of common patterns.epochtime.toolsConvert between Unix epoch timestamps and human-readable dates in any time zone, in seconds or milliseconds, in both directions.cidrcalculator.netWork out network and broadcast addresses, host ranges and subnet sizes from CIDR notation, with clear breakdowns for network planning.subnetmaskcalc.netCalculate subnet masks, host counts and address ranges, with worked examples and code snippets in several languages for network engineers.barcodeandqr.comGenerate barcodes and QR codes in many formats and export them print-ready as PNG or PDF, all rendered locally in your browser.removemetadata.toolsStrip hidden metadata — EXIF, location, author and more — from images, PDFs, Office files, audio and video in your browser, so nothing is uploaded.corepdftools.comMerge, split, compress, rotate and password-protect PDF files client-side, keeping your documents private because they never leave your device.colorcodekit.comConvert color codes between HEX, RGB, HSL and more, build palettes and gradients, and export tokens for SwiftUI, Flutter and Jetpack Compose.pictoolkit.comA toolkit of browser-based image utilities for resizing, converting and editing pictures without uploading them anywhere.

Text & time· 9

wordcounterfree.comCount words, characters, sentences and paragraphs and estimate reading time as you type, useful for essays, articles and content limits.transformcase.comConvert text between upper case, lower case, title case, sentence case and more in one click, handy for cleaning up copy and code.textrepeat.netRepeat, duplicate and generate blocks of text quickly, with control over separators and counts for testing and formatting.numtotext.comConvert numbers to words, including Indian-rupee amounts in words for cheques and invoices, with clean copy-ready output.unitcheatsheet.comA fast reference and converter for units of length, weight, volume, temperature and more, with the conversions you actually look up.calculatehours.netAdd up the hours between start and end times, including overnight spans and breaks, useful for timesheets, shifts and payroll.clockwithus.comCheck the current time across world cities and time zones at a glance, for scheduling calls and coordinating across regions.theagecalculator.netCalculate exact age in years, months and days, plus milestones, birthday countdowns and age comparisons between people.passwordstrength.netTest how strong a password is and how long it would take to crack, checked locally and never sent anywhere, with practical guidance.

Health, education & everyday math· 5

calorieskit.comA suite of calorie, macronutrient and body-composition calculators — daily needs, protein targets, lean body mass and more — with clear methodology.bmibmrcalc.comCalculate BMI, BMR and TDEE with adaptive-thermogenesis and macro features that go beyond the basic formulas most calculators stop at.gpacalculatorhq.comCalculate GPA and CGPA across US, Canadian, Indian and Pakistani grading systems, with verified per-university scales and a grade planner.fractionsteps.comAdd, subtract, multiply and divide fractions with full step-by-step working shown, plus worksheets for practice.measurechef.comConvert and scale cooking measurements — cups, grams, ounces and millilitres — and resize recipes up or down without the guesswork.
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