Free Online Tools for Everything You Do

Ical Gen

Generate iCalendar (.ics) event strings.

iCal Parser

High-performance interactive iCalendar (.ics) Parser, RFC 5545 calendar validator, and JSON converter with 100% SEMrush keyword optimization.

ICH Volume Calculator (ABC/2) — Intracerebral Hemorrhage Volume

Free ICH volume calculator using the ABC/2 method (Kothari et al. 1996). Enter A, B, C in mm or cm, choose ABC/2, ABC/2.3 or ABC/3, get hemorrhage volume in mL. Educational estimate — not medical advice.

iCalendar .ICS File Generator & Event Maker

Free online iCalendar .ics file generator and event maker. Create ics file for Google Calendar, Apple Calendar, and Outlook with clean RFC 5545 ics calendar format.

Ideal Gas Law Calculator (PV = nRT) - Solve P, V, n, T + Moles↔Mass + Density

Free ideal gas law calculator: solve PV=nRT for pressure, volume, moles or temperature with full unit mixing, convert moles↔mass via molar mass, compute ideal-gas density ρ=PM/RT, and see R in every u

Ideal Rocket Equation Calculator (Tsiolkovsky)

Solve the Tsiolkovsky ideal rocket equation in every direction: delta-v, specific impulse, mass ratio, initial/final mass and propellant mass. Multi-stage rockets, propellant presets and mission delta

Ideal Body Weight (IBW) Calculator — Devine, Robinson, Miller & Hamwi | nrtechstudio.com

Free ideal body weight (IBW) calculator: compares the 4 classic formulas — Devine (1974), Robinson (1983), Miller (1983) and Hamwi (1964) — plus BMI h

Email Password Leak Checker & Security Lookup

Free online email password leak checker and breach lookup. Learn how to check the password leak online, identify email address vulnerabilities, verify compromised passwords, and run URL legit check safely.

IG Line Break Generator — Invisible Spaces for Instagram Captions

Free IG line break generator. Add invisible U+2800 spacers so blank lines survive in Instagram captions and bios, with a live 2,200-character counter. 100% client-side.

IIFYM Macro Calculator — Protein, Carbs & Fat Targets

Free IIFYM macro calculator: estimate your TDEE with Mifflin-St Jeor, pick cut, maintain or bulk, then get adjustable protein, fat and carb targets in grams and % of calories — plus a meal split table.

Illinois Overtime Pay Calculator — 1.5× for Hours Over 40

Calculate Illinois overtime pay: 1.5× the regular rate for hours over 40/week (federal FLSA rule) + Illinois $15.00 and Chicago $16.60 minimum wage check. Hourly, salary-to-weekly, scenario comparison, FAQ modes. Free.

Image Morse Code Translator

Full morse code translator — audio, text, image/picture to morse code, morse code into english, decode morse audio, morse sound decoder, morse code copy paste, and more.

Uncompressed Image Size Calculator — Bitmap Memory in Bytes, KiB & MiB | nrtechstudio.com

Calculate uncompressed image memory size from width, height and bit depth: exact bytes, KiB/MiB, KB/MB, batch and video RAM planner, step-by-step math.

Image to Base64 Converter

Free online image to Base64 converter. Upload any image and instantly get its Base64 encoded string, Data URI, and CSS background-image code. Supports PNG, JPG, GIF, WebP, SVG.

Image to Black & White Converter — Free, 100% in Browser

Turn photos black-and-white free right in your browser: BT.709/BT.601 grayscale, 1-bit threshold, Floyd–Steinberg & Bayer dithering, Photocopy/Newspaper/Stamp/Sketch presets, batch ZIP. No upload — images never leave your device.

Image To Json

Img Resizer Calc

Calculate proportional dimensions for resizing images.

Image to Markdown Converter

Standalone professional image-to-markdown generator. Convert an image URL to Markdown image syntax with alt text, title, linked-image, reference-style, batch gallery and HTML img fallback.

Immediate Annuity Calculator (SPIA) — Lifetime Monthly Income Estimate

Free single-premium immediate annuity (SPIA) calculator: estimate lifetime monthly income from a lump sum using age, sex, a mortality life table, and payout options — life-only, period certain, joint and survivor. 100% client-side.

Impact Energy Calculator

Free impact energy calculator: kinetic energy (E = 1/2 m v^2), drop impact (E = m g h), inverse solvers for velocity and mass, with joules, kJ, ft-lbf and calorie output plus equivalent drop height.

Imperial to Metric Conversion Calculator - Free Online Converter

Free imperial to metric conversion calculator: inches to cm, feet to meters, miles to km, pounds to kg, ounces to grams, Fahrenheit to Celsius, gallons to liters (US vs imperial). Exact factors, 100% client-side.

Impermanent Loss Calculator (v2 & v3) — DeFi LP Risk

Free impermanent loss calculator for DeFi liquidity pools: Uniswap v2 50/50 pools and v3 concentrated ranges. Compare LP vs HODL value, find the fee APR needed to break even. Not financial advice.

Implantation Calculator — Estimate Your Implantation Window, Bleeding Timing & hCG Test Dates

Estimate your implantation window (ovulation +6 to +12 days, peak 8-10 DPO), likely implantation bleeding timing vs your expected period, and the earl

Inch Lbs to Nm Converter: In·lb to N·m Torque Conversion

Free inch lbs to Nm converter. Convert in·lb to N·m and back, plus ft·lb, kgf·m and ozf·in. Exact factor 0.11298482903, torque table, bolt specs, and torque-wrench context. Works offline.

Inch-Pounds to Foot-Pounds Converter (in·lb to ft·lb) - Free Torque Tool

Free inch-pounds to foot-pounds converter: convert torque both ways (1 ft·lb = 12 in·lb) with newton-metre output, a quick reference table, and torque-wrench range guide. 100% client-side.

Inch to Meter Converter: in to m Calculator with Formula

Free inch to meter converter and meter to inch converter. Convert inches to meters (multiply by 0.0254) or meters to inches (divide by 0.0254) with live results, feet-and-inches helper, quick conversion table, 20 popular conversions, and FAQ.

Inches to Yards Converter: In to Yd Calculator

Free inches to yards converter and yards to inches calculator. 1 yard = 36 inches exact. Includes quick tables, formula, fabric, football and construction contexts.

Incidence Rate Calculator — Person-Time Rate, Cumulative Incidence & Rate Ratio (Free)

Free incidence rate calculator for epidemiology: compute incidence rate from new cases and person-time (per 1,000 / 10,000 / 100,000 person-years), cu

Income Elasticity of Demand Calculator

Interactive income elasticity of demand calculator: compute Ei with midpoint or point formulas, classify luxury, necessity, and inferior goods, reverse solver, and two-good comparator.

Inductive Reactance Calculator - XL = 2πfL Solver

Free inductive reactance calculator: compute XL = 2πfL, 3-variable solver (XL/f/L), XL vs frequency table, ideal impedance + +90° phase angle. 100% offline.

Inductor Energy Calculator - E = 1/2 L I^2

Free inductor energy calculator: solve E = ½LI² in all three directions (energy, inductance, current) with unit conversion and a capacitor-energy comparison readout.

Infant Tylenol Dosage Calculator by Weight (160 mg/5 mL) — Dose, Tracker & Safety Check

Educational infant/children's Tylenol (acetaminophen 160 mg/5 mL) dose estimator: weight-based dose (15 mg/kg), label chart, 24-hour dose log with nex

Inflation Calculator — What Is Your Money Worth Over Time? (1913–2026, 6 Countries)

Free inflation calculator: convert money between any two years (1913–2026) for the US, UK, Euro area, Canada, Australia and Indonesia using official CPI data. See equivalent value, total & annual inflation, purchasing-power chart and year-by-year table.

Portfolio Information Ratio Calculator — NRTechStudio

Calculate portfolio information ratio: IR = (Rp − Rb) ÷ tracking error. From aggregate figures or a return series, with an inverse solver, a two-manager comparator, and annualization.

INI to JSON Converter

Enterprise-grade INI to JSON Converter, Online INI Parser, and Configuration Transformer with 100% SEMrush keyword optimization.

Injury Settlement Calculator — Personal Injury, Car Accident & Workers' Comp Lab

Free injury settlement lab: personal injury multiplier estimator, car accident settlement calculator with diminished value, interactive multi-state workers' comp body-part payout chart, state comparison view, and net-after-fees take-home calculator. 100% client-side, no signup.

Insertion Loss Calculator — Calculate IL from Power & Voltage (dB)

Free insertion loss calculator: IL = 10·log10(Pin/Pout) for power and 20·log10(Vin/Vout) for voltage. 3-way solver, W/mW/dBm/V/mV units, dB-to-linear-ratio conversion, and multi-stage cascade.

Instrument Size Lab — Guitar, Violin, Viola, Cello & Ukulele Size Finder

Find the right instrument size: guitar size by height & age, violin fractional size by arm length, viola, cello, and the right ukulele (soprano vs concert vs tenor vs baritone). Free, private, no sign-up.

Integer to Roman Numerals Converter — Convert Numbers to Roman Numerals (Free)

Convert integers to Roman numerals free: 1–3999 standard plus vinculum overline notation to 3,999,999. Batch mode, reference table, 100% private.

Interest Coverage Ratio Calculator — nrtechstudio

Calculate interest coverage ratio (ICR) from EBIT or EBITDA, reverse-solve a target ICR, and compare two companies — with substitution steps and descriptive labels. An educational estimate, not investment advice.

Interest-Only Mortgage Calculator — IO Payment, Amortization & Balloon

Free interest-only mortgage calculator: compute IO-phase monthly payment, payment after the interest-only period ends, payment shock, balloon amount, total interest, and compare vs a fully amortizing loan.

Interest Paid Monthly Calculator & APR Solver

Interactive interest paid monthly calculator, calculate monthly interest from APR, and interest over time calculator amortization.

Interest Per Day Calculator — Daily Interest by Day-Count Convention

Free interest per day calculator: enter principal, annual rate, and day-count convention (Actual/365, Actual/360, 30/360) to get daily interest and period totals. Includes reverse mode to find the rate from a daily interest amount.

Implied Interest Rate Calculator — Find the Rate from Installment & Term

What percent is your loan interest really? Find the implied interest rate from principal, installment, and term with a numeric solver — plus EAR, a 2-offer comparator, and a sensitivity table. Free, 100% private in your browser.

IRR Calculator — Internal Rate of Return from Cash Flows

Free IRR calculator: compute internal rate of return from a cash flow series with a transparent bisection iteration table, NPV profile, 2-project comparison, and target IRR solver. 100% in the browser, no sign-up.

Stock Intrinsic Value Calculator (DCF) — Free Cash Flow, Terminal Value, WACC

Calculate a stock’s intrinsic value with DCF: multi-year FCF projections, Gordon/exit-multiple terminal value, WACC discount rate, down to intrinsic value per share + margin of safety, reverse DCF, scenarios, and a sensitivity table.

Inventory Turnover Calculator — nrtechstudio

Inventory turnover calculator: compute the inventory turnover ratio from COGS and beginning/ending inventory, DIO (days inventory outstanding), reverse target-turnover solver, and two-company comparator. 100% in the browser.

Modular Inverse Calculator — Extended Euclidean Algorithm with Steps

Free modular inverse calculator: compute a⁻¹ mod m with the extended Euclidean algorithm, full step table, coprimality check, and a·x ≡ 1 verification.