Free Online Tools for Everything You Do
Browse 2,706+ free interactive tools - home improvement estimators, pet calculators, cooking converters, automotive tools, finance planners, fitness calculators, developer utilities and more. No sign-up. 100% private. Runs entirely in your browser.
Plastering Calculator — Cement, Sand & Water Estimator | nrtechstudio.com
Free plastering calculator: cement bags, sand and water for any wall or ceiling. Mix ratios 1:3 to 1:6, dry-volume factor, two-coat mode, cost.
Plastic Footprint Calculator — Estimate Your Annual Plastic Use
Free plastic footprint calculator: enter your weekly and monthly plastic habits to estimate kilograms of plastic per year, see bottle equivalents, and get reduction tips ranked by impact.
Playhouse Size Calculator — Doors, Loft, Lumber & Cost Planner
Free playhouse size calculator: 7 modes for kid-sized doors, loft rails, lumber takeoff, skids, safety checklist, kit vs DIY cost.
Playroom Size Calculator — How Big Should a Playroom Be?
Free playroom size calculator: square feet per child, toy storage, reading nook, craft table, activity mat, safety clearance and growth plan.
PNG to PDF Converter Free — Lossless, No Upload
Combine multiple PNGs into one free PDF, 100% in the browser. Lossless mode with no quality loss (transparency preserved), compressed JPEG option,
Podcast Cover Art Checker — Validate, Resize & Preview (3000×3000)
Free podcast cover art checker: validate your artwork against Apple Podcasts specs (1400–3000px, square, JPG/PNG, RGB, 72dpi), one-click resize to 3000×3000, preview in Apple Podcasts / Spotify / YouTube / Pocket Casts mockups, 55px legibility test and safe-area overlay. 100% private — runs in your browser.
Podcast Revenue Calculator — Ads, Sponsorships & Multi-Stream Income Estimator
Free podcast revenue calculator: estimate monthly income from ads (pre/mid/post-roll CPM), sponsorships, subscriptions, donations, affiliates & merch. Includes 2026 CPM benchmarks by genre, reverse goal planner & scenario compare. 100% private — runs in your browser.
Podcast RSS Generator — Apple Podcasts Feed XML
Generate Apple Podcasts RSS feed XML with iTunes tags.
Point Buy Calculator 5e — D&D Ability Score Calculator
Free D&D 5e point buy calculator. Spend your 27 points across STR, DEX, CON, INT, WIS, CHA with the official cost table, live modifiers, standard array preset, and custom DM budgets.
Poise to Stokes Converter — Dynamic ↔ Kinematic Viscosity
Free poise to stokes converter: convert dynamic viscosity (poise, centipoise, Pa·s, lb/ft·s) to kinematic viscosity (stokes, centistokes, m²/s, ft²/s) via density ν=μ/ρ. Fluid presets, no signup, 100% client-side.
Poiseuille's Law Calculator — Flow Rate, 5-Way Solver, Laminar Check
Free Poiseuille's law calculator: solve Q = π·ΔP·r⁴/(8·η·L) five ways (flow rate, pressure drop, radius, viscosity, length), check laminar flow with R
Poisson's Ratio Calculator — ν from Strain, Modulus Relations & 3D Deformation
Free Poisson's ratio calculator: ν = −ε_lateral/ε_axial from measured strains, isotropic modulus relations E = 2G(1+ν) = 3K(1−2ν), and 3D deformation
Polynomial Division Calculator with Steps — Long & Synthetic Division
Free polynomial division calculator with full steps: divide polynomials by long division or synthetic division, see quotient, remainder and the verification divisor × quotient + remainder = dividend.
pom.xml Generator
High-performance interactive Apache Maven POM.xml Generator, project file builder, and Maven archetype CLI synthesizer with 100% SEMrush keyword optimization.
Pomodoro Timer — Focus Sessions Online
Free online Pomodoro timer: 25-minute focus sessions with short and long breaks, custom cycles, sound alerts and daily stats. No signup, 100% client-side.
Pond Size Calculator — 7 Ways to Size Your Pond
How big should your pond be? Free 7-mode pond size calculator: volume in gallons, koi capacity, depth zones, acre-pond estimates, pump sizing and yard
Pool Chlorine Calculator — Dose in ppm, Shock & Tablet Schedule
Pool chlorine calculator: dose liquid chlorine, bleach, cal-hypo, dichlor & trichlor by ppm, shock treatments, weekly tablet schedule and CYA warnings
Pool Diamond Lab — Diamond System, Bank & Kick Shot Aiming Calculator
Free interactive pool diamond system lab: click cue ball + object ball to compute aim diamonds for 1/2/3-rail kicks and bank shots via mirror geometry, Corner-5 solver, Plus-2 & Sid guides, diamond numbering charts, and a practice drill. 100% client-side.
Pool Heater Size Calculator — BTU, Heat-Up Time, Cost & Cover Savings
Free pool heater size calculator: BTU sizing, heat-up time, heat loss, gas vs heat pump cost, solar cover savings, sizing charts and install guidance.
Pool House Size Calculator — 7 Free Planning Tools | nrtechstudio
Free pool house size calculator: 7 tools to size by swimmers, amenities, pool area, budget and setbacks, with build-cost estimates.
Pool Pump Size Calculator — GPM, HP, Head Loss, Energy & Filter Sizing
Free pool pump size calculator: GPM from volume and turnover, HP sizing chart, head-loss estimator, variable-speed energy savings, filter and pipe gui
Pool Salt Calculator
Pool salt calculator: how much salt to add to a saltwater pool in lb, kg and 40-lb bags, salt level check, salt cell sizing guidance and cost estimator.
Pool Size Calculator — 7 Ways to Size Your Swimming Pool
Free pool size calculator with 7 modes: family, lap, compact and kids sizing, depth planner, deck space, setbacks and yard-fit check. 100% client-side
Pool Volume Calculator (Gallons & Liters) — Rectangular, Oval & Round Pools
Free pool volume calculator: enter length, width and average depth for rectangular, oval or round pools. Get volume in gallons and liters plus cubic feet, cubic meters, fill time and a rough shock-chlorine estimate.
Pooled Standard Deviation Calculator | 2–5 Groups, Naive vs Pooled, t-Test
Free pooled standard deviation calculator: enter n, mean and SD for 2–5 groups to get pooled variance, pooled SD and df, compare against the naive combined SD, and see a two-sample t-test worked example.
Porch Size Calculator: Plan Front Porch Dimensions & Layout
Free porch size calculator: plan entry, seating, dining, wraparound and screened porch dimensions, door swing clearance and setback checks in one tool
Post-Judgment Interest Calculator — Daily Accrual, Payments & State Rates | nrtechstudio.com
Post-judgment interest calculator: principal, statutory rate, and days. Supports partial payments, daily accrual, compounding, and per-state rate presets.
Standalone - Post Office Monthly Income Scheme Calculator
POMIS calculator — monthly payout at the official 7.4% p.a. rate
Potting Bench Size Calculator — Height, Width, Materials, Sink & Cost | nrtechstudio.com
Potting bench size calculator: height matched to you, width from pots and soil bags, shelf storage, sink cutout, lumber list, balcony version and cost
Pounds to Grams Converter (lb to g) - Exact 453.59237
Convert pounds to grams and grams to pounds with the exact definition: 1 lb = 453.59237 g. Free two-way lb to g calculator with precision control, conversion table, and worked examples.
Power Dissipation Calculator — Resistor, Transistor, Thermal & Heatsink | nrtechstudio
Free power dissipation calculator: resistor P=V²/R 3-way solver with temperature derating, BJT/MOSFET/diode power, junction temperature Tj=Ta+P·Rθja,
Power to Weight Ratio Calculator — W/kg, hp/ton, Cycling FTP
Free power-to-weight ratio calculator: watts per kg (cycling FTP), hp/ton and kW/tonne (cars), hp/lb (aviation). Unit converter + reverse solver included.
Power Unit Converter — Watts, HP, kW, BTU/h, dBm | nrtechstudio
Free power unit converter: watts, mW, kW, MW, GW, mechanical/metric/electric horsepower, BTU/h, tons of refrigeration, dBm/dBW. Plus horsepower guide, appliance wattage database with cost calculator, and generator/solar sizer. 100% client-side.
Powerlifting Score Calculator — Wilks, Wilks 2.0, DOTS IPF GL Points
Free powerlifting score calculator: compute Wilks, Wilks 2.0, DOTS and IPF GL points side by side from your squat, bench, deadlift and bodyweight. Includes strength level classification and attempt planner. 100% private, runs in your browser.
PPI Calculator — Pixels Per Inch for Any Screen
Free PPI calculator: pixels-per-inch from resolution and screen size, plus megapixels, aspect ratio and pixel pitch. 100% client-side.
PPM to Molarity Calculator — Convert ppm ↔ mol/L, mM, µM (Free)
Free ppm to molarity calculator: convert ppm ↔ mol/L, mM, µM, mg/L, ppb, ppt with molecular weight & density correction. Formula, worked examples, common ions table.
PPM to PPT Converter — ppm, ppb, ppt, ppq & Percent Converter | nrtechstudio.com
Free ppm to ppt converter: convert parts per million, billion, trillion, quadrillion and percent with show-your-work steps. Includes mg/L water mode, scientific notation and a full scale reference. 100% private — runs in your browser.
Prandtl Number Calculator — Pr = μ·c_p/k Solver, Fluid Table & Boundary-Layer Guide
Free Prandtl number calculator: Pr = μ·c_p/k in 4 solve directions (SI + imperial units), 11-fluid Prandtl table with temperature interpolation, and c
Pregnancy Due Date Calculator — EDD by LMP, Conception, IVF & Ultrasound
Free pregnancy due date calculator: estimate your EDD from last period (Naegele's rule), conception date, IVF embryo transfer, or ultrasound dating. Get your trimester timeline, personalized week-by-week milestones, pregnancy countdown, and calendar reminders. 100% client-side, no signup.
Basic Present Value Calculator — Single Lump-Sum PV
Free present value calculator (basic): discount one future lump sum to today's money with PV = FV/(1+r)^n, discount factor, and year-by-year schedule.
Present Value of Cash Flows Calculator — PV of Uneven Streams
Free present value of cash flows calculator: discount an uneven stream of future cash flows to today's dollars, with a per-period PV table.
Prettier Config Generator
High-performance interactive Prettier Config Generator, .prettierrc builder, and code formatting architect with 100% SEMrush keyword optimization.
Price Per Liter to Price Per Gallon Calculator
Convert fuel price per liter to price per US gallon and imperial gallon, compare two fuel prices, and calculate fuel cost per 100 km or 100 miles. Free calculator.
Price Per Sqft Calculator — $/Sq Ft, Compare & Convert
Free price per sqft calculator: $/sq ft from price and area,
Price Per Weight Calculator — $/Lb, $/Oz, $/Kg, Compare
Free price per weight calculator: $/lb, $/oz, $/kg, $/g unit prices,
Prime Number Checker — Test Primality & Factorize
Free online prime checker: test if a number is prime with a deterministic Miller-Rabin test (exact for all n < 2^64), full prime factorization with Pollard Rho, next/previous prime, prime gaps, and nth prime finder. 100% client-side.
Priming Sugar Calculator — Per-Bottle Dosing, Sugar DB & Keg PSI Chart
Free priming sugar calculator for homebrew beer: exact grams per batch, per-bottle dosing for any bottle size, 8-sugar database, forced-carbonation keg PSI chart, style CO2 targets, and bottle-bomb safety guardrails. 100% client-side.
Principal Stress Calculator (2D & 3D) — Mohr's Circle, von Mises
Free principal stress calculator: 2D & 3D principal stresses, Mohr's circle, principal angles, max shear stress, and von Mises equivalent stress. 100% client-side, no sign-up.
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How to Use the Tools Directory
Every tool is a single interactive page: enter your inputs, get instant results, no account needed. Use the search box (shortcut: press /) to jump straight to a tool, or browse categories when you are exploring. Each card links to the tool's permanent URL, which you can bookmark or share.
Because all computation happens in your browser, the tools are fast, private, and free forever. If a result looks wrong, use the one-click report control on the tool page so it can be fixed.
Tool Categories at a Glance
| Category | What you will find | Example tasks |
|---|---|---|
| Developer | Encoders, formatters, regex, network tools | Format JSON, test regex, subnet a network |
| Finance | Tax, loans, salary, investing | Estimate tax brackets, amortize a loan |
| Home improvement | Estimators, measurements, materials | Size a wire, estimate paint or flooring |
| Health & fitness | Body metrics, nutrition, workouts | Track BMI, plan calories, score fitness tests |
| Math & science | Converters, geometry, statistics | Convert units, solve triangles |
| Text | Counters, sorters, generators | Count words, alphabetize a list |
| Color | Pickers, converters, checkers | Convert HEX to RGB, check contrast |
| Everyday life | Cooking, travel, automotive, pets | Convert recipes, plan fuel costs |
Popular Tasks and Where to Start
| I want to... | Start with | Why |
|---|---|---|
| Convert between number bases | Binary Converter | Step-by-step base conversion with charts |
| Validate and format data | JSON Formatter | Pretty-print and check JSON instantly |
| Count words for an essay | Word Counter | Words, characters, reading time |
| Check password strength | Password Strength Meter | Entropy-based strength scoring |
| Grade text readability | Readability Score | Flesch-Kincaid and grade levels |
| Audit color contrast | Accessibility Checker | WCAG contrast ratios in one click |
Tools Directory FAQ
What is the NRTechStudio tools directory?
It is a free catalog of more than 2,700 interactive web tools: calculators, converters, generators, and checkers for developers, finance, home improvement, health, education, and everyday tasks.
Are all the tools really free?
Yes. Every tool in the directory is free to use with no sign-up, no trial, and no paywall. They run entirely in your browser.
Do I need to create an account?
No. There are no accounts, logins, or subscriptions. Open a tool and use it immediately.
Is my data private when I use these tools?
Yes. The tools are 100% client-side: your inputs are processed by JavaScript in your own browser and never sent to a server.
How do I find the right tool?
Use the search box at the top of the directory (press / to focus it), or browse by category. Every tool card shows a short description of what it computes.
Do the tools work on mobile?
Yes. The directory and the tools use responsive layouts that adapt to phones, tablets, and desktops.
How many tools are there?
The directory holds more than 2,700 tools and grows regularly as new calculators and converters are published.
Can I request a new tool?
Yes. Each tool page has a report/feedback control you can use to request features or new tools; requests help prioritize what gets built next.
Are the tools accurate?
Calculators use published formulas and reference data (tax tables, NEC ampacity, standard conversions). Each tool page documents its method, and issues can be reported in one click for a fix.
Do tools work offline?
Once a tool page has loaded, most tools keep working without a connection because the logic is client-side JavaScript. The directory search needs the page loaded first.
What categories are covered?
Developer utilities, finance and tax, home improvement, health and fitness, math and science, text tools, color tools, networking, education, and everyday life calculators, among others.
Can I bookmark or share a tool?
Yes. Every tool has its own permanent URL under nrtechstudio.com/tools/, which you can bookmark or share directly.
Is there an API for these tools?
The tools are interactive web pages, not API endpoints. The underlying math is plain JavaScript you can inspect in the page source.
Why do some tools show ratings?
Ratings aggregate user feedback to surface the most trusted tools and flag pages that need fixes or better explanations.
How often are new tools added?
New tools are published on a continuous pipeline, prioritized by measured search demand and by user requests from the feedback controls.
Who builds these tools?
NRTechStudio, an independent tools studio focused on free, private, client-side utilities that respect user privacy.