Free Math & Calculators Tools & Calculators
Browse 710+ free interactive math & calculators calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
Baby Formula Feeding Calculator — How Much Formula by Weight Age (AAP-Based)
Free baby formula feeding calculator: how much formula per day by weight (AAP 2.5 oz/lb rule) and by age (ml/kg method), ounces per feeding, feeding schedule by month, combination feeding, and formula cost per month. 100% client-side, no signup.
Baking Substitution Finder — 49 Ingredient Substitutes with Exact Ratios
Out of buttermilk, eggs, or butter? Find the exact baking substitution with precise ratios, dietary filters (vegan, dairy-free, gluten-free), and baker's adjustment notes. 49 ingredients, 100+ tested substitutes. Free, no signup, 100% client-side.
Ballistic Coefficient Calculator — SD, BC, G1/G7 Form Factor & Missing-Variable Solver
Free ballistic coefficient calculator: sectional density SD=m/d², BC=SD/i for G1 and G7 drag models, missing-variable solver (BC, SD, i, mass, diameter), typical form-factor table, unit converter, and
Balloon Payment Loan Amortization Schedule
Full amortization table calculator, balloon payment loan amortization schedule, car payment amortization calculator, mortgage amortization, auto finance, create amortization schedule.
Baluster Spacing Calculator — Even Layout, 4-Inch Rule Check (Stair & Level)
Free baluster spacing calculator: even baluster layout for level and stair railings, baluster count optimizer, 4-inch sphere rule (IRC) pass/fail check, newel post deduction, metric + imperial units, cut list. 100% client-side.
Bank Loan Calculator & Loan Percentage Rate Calculator
Free online bank loan calculator and loan percentage rate calculator. Calculate monthly payments, analyze loan repayment terms, inspect amortization schedules, and compute total interest.
Barbell Plate Calculator (kg lb) — Visual Plate Loader
Free barbell plate calculator: enter your target weight and see exactly which plates to load per side, with a visual bar diagram, plate inventory mode, warm-up set generator, kg/lb units and fractional plates. 100% private, works offline.
Base16 to Base 10 – Universal Base Calculator & Numbering System Converter
Base16 to base 10, convert into hex, how to turn a mixed number into a decimal, base calculator, how to turn a mixed fraction into a decimal, deg min sec to decimal, int to hex, base to base conversion, base 10 calculator, convert the numeral to a numeral in base ten, convert base 2 to base 10, base 5 converter, base 6 converter, numbering system converter, 1a hexadecimal to decimal, 2a hex to decimal, 0x20 to binary, binary 111 to decimal, 100 to hexadecimal.
Base 2 (Binary) Converter & Calculator
Professional Base 2 Number Converter, Signed Binary Calculator, Two's Complement Solver, and Binary Arithmetic Engine.
Base64 to HEX Converter Online
Free online base64 to hex converter, hex to base64 calculator, and base64 to text decoder. Convert base64 to image, base64 to binary, and base64 to string.
BC to AD Converter — BCE/CE & Astronomical Year Converter | nrtechstudio
Free two-way BC/BCE to AD/CE year converter. Convert any year between historical and astronomical numbering (no year zero handled honestly) and compute elapsed years between two dates across eras. 100% client-side.
Beam Load Calculator — Reactions, Shear, Moment & Deflection
Free simply-supported beam load calculator: support reactions, shear force & bending moment diagrams, and deflection estimates for point, uniform, and triangular loads. Metric + imperial, wood & steel presets.
Beat Frequency Calculator — f_beat = |f₁ − f₂| + Missing-Frequency Solver
Free beat frequency calculator: compute f_beat = |f1 − f2|, beat period T = 1/f_beat, solve the unknown tone (f2 = f1 ± f_beat), with Hz/kHz/BPM units and tuning examples.
Bee Syrup Calculator — Sugar Water Ratios, Batch Mixer & Feeding Planner
Free bee syrup calculator: 1:1 and 2:1 sugar syrup recipes for bees by weight, batch mixer (sugar + water for any volume), fondant & invert modes, hive feeding planner with seasonal schedules, feeder refills, and sugar cost estimator. 100% client-side.
Sheet Metal Bend Calculator — Bend Allowance, Tonnage, V-Die & Flat Pattern (Free)
Free sheet metal bending suite: bend allowance & deduction calculator, multi-bend flat pattern, K-factor lookup, press brake tonnage (air/bottoming/coining), V-die selector and punching force. Metric + imperial. 100% private, runs in your browser.
Bernoulli Equation Calculator — Solve P, v, z, Venturi & Head Terms
Free Bernoulli equation calculator: solve for the missing variable (P1, v1, z1, P2, v2, z2) in P/rho*g + v^2/2g + z with full head-term breakdown, venturi meter mode, manometer input, and unit convers
Binary Code Translator & Base 2 Calculator
Precision binary code translator, translate binary to English, denary to binary calculator, hex to decimal, signed binary converter, and decimal binary hex chart.
Binoculars Range Calculator — Mil-Dot & MOA Rangefinder Estimator
Estimate distance with binoculars or a riflescope: mil-dot range formula (range = size × 1000 ÷ mils), MOA variant, missing-variable solver, presets, and unit conversion. Free, no sign-up.
Biweekly Time Card Calculator & Timesheet Hours
Interactive biweekly time card calculator and timesheet hours tracker for payroll, overtime, and gross wage calculations.
Black Hole Temperature Calculator — Hawking Temperature T = ħc³/(8πGMk)
Free black hole temperature calculator: compute Hawking temperature T = ħc³/(8πGMk_B) from mass in solar masses or kg, with Schwarzschild radius and CMB comparison. Includes Sgr A*, M87*, stellar and
Blackbody Radiation Calculator — Stefan-Boltzmann, Wien & Planck
Free blackbody radiation calculator: total radiated power (Stefan–Boltzmann law), peak wavelength (Wien's displacement law), and spectral radiance (Planck's law). Two-way temperature ↔ power solver, p
Block Mortar Calculator — Blocks, Mortar Bags & Site Mix Estimator
Estimate concrete block count, mortar volume, 60/80-lb premix bags, and site-mix cement, lime, and sand for a CMU block wall. Based on manufacturer coverage data.
Custom Software Development Cost Estimator
Interactive software development cost calculator, mobile app scoping estimator, and enterprise engineering architecture planner.
Blood Volume Calculator (Nadler Formula) | nrtechstudio.com
Free blood volume calculator using the Nadler formula (sex, height, weight) with Gilcher rule-of-fives comparison, metric/imperial inputs, and blood-d
Board and Batten Layout Calculator — Even Spacing, Edge Margins & Cut Marks
Free board and batten layout calculator: enter wall width, batten width and target spacing (or batten count) to get even on-center spacing, edge margins, batten center marks from the corner, total linear feet of stock, and a to-scale wall preview. 100% client-side, no signup.
Board Foot Calculator: Project Mode, Cost by Species & Reference Chart
Free board foot calculator with project mode (multi-board cut lists), reverse solver, waste & milling presets, nominal-to-actual lumber tables, an editable species price database for cost estimates, and a BF reference chart. 100% client-side.
Board Game Collection Tracker: Free Play Log, Cost-Per-Play & Shelf of Shame
Free board game collection tracker and organizer: log every play, auto-compute cost per play, track your collection's value, and shame your unplayed games. No sign-up, 100% client-side, CSV export.
Board Game Picker: What Should We Play? (Quiz + 150 Games)
Can't decide what board game to play? Take the 60-second quiz or use smart filters to get ranked recommendations from 147 curated board games — 2-player, party, family, co-op & more. Free, no sign-up.
Board Game Score Sheet & Score Calculator — Free, Printable, No Sign-Up
Free board game score sheet & score calculator: multi-player score pad with auto-totals, rankings, winner highlight, game presets (Catan-style, Ticket-to-Ride-style, Wingspan-style), printable scoresheet, free CSV export, and local save. No sign-up.
Boat Capacity Lab — USCG Boat Capacity, Weight & Max HP Calculator
Free boat capacity calculator suite: USCG persons capacity (L×W/15), max weight capacity, federal max horsepower (33 CFR 183.53), ABYC H-35 pontoon worksheet, electric outboard sizing, and outboard shaft-length guide. 100% client-side.
Body Surface Area (BSA) Calculator — DuBois, Mosteller, Haycock, Gehan-George, Boyd
Free body surface area (BSA) calculator: compute BSA in m² with DuBois, Mosteller, Haycock, Gehan & George, and Boyd formulas side by side, plus the average and optional mg/m² dose calculation. Educational tool — not medical advice.
Body Type Calculator — Ectomorph, Mesomorph, Endomorph Scores
Free body type calculator: get your somatotype blend (ectomorph, mesomorph, endomorph) from height, weight, wrist circumference and frame size. Male and female. 100% client-side.
Bohr Model Calculator — Hydrogen Energy Levels, Radius & Spectral Lines
Free Bohr model calculator for hydrogen-like atoms: energy levels E_n, orbital radii r_n, photon wavelength/energy for electron transitions (n2→n1), Lyman/Balmer/Paschen series labels, and spectral-li
Boiler Size Calculator — BTU/hr, kW & Boiler HP by Climate Zone
Free boiler size calculator: enter floor area, climate zone, insulation, ceiling height and windows to get your heat loss and recommended boiler size in BTU/hr, kW and boiler horsepower — with fuel efficiency adjustment and an oversize short-cycling checker. 100% client-side, no signup.
Bolt Circle Calculator (BCD/PCD) — Lug Pattern, Spacing & Hole Coordinates
Free bolt circle diameter (BCD/PCD) calculator: find BCD from adjacent bolt spacing for 3/4/5/6/8-lug wheels and flanges, reverse BCD to spacing, get machining X/Y hole coordinates, and match the nearest standard bolt pattern. 100% client-side.
Bolt Torque Calculator — Metric & SAE Tightening Torque (Free)
Free bolt torque calculator: T = K·F·d for metric bolts M6–M36 (classes 8.8/10.9/12.9) and SAE bolts (Grade 5/8). K-factor presets, clamp load, and a standard torque chart.
Boltzmann Factor & Thermal Population Ratio Calculator
Calculate the Boltzmann factor exp(−ΔE/kT), the thermal population ratio N2/N1, and temperature from a measured ratio. Exact SI 2019 constants. Free, 100% client-side.
CSS Border Radius & Circle Radius Generator
Free visual CSS border radius with border generator and circle radius calculator. Create buttons, rounded cards, circles, and copy clean CSS code.
Boxing Glove Size Calculator — Hand, Weight & Oz Fit Lab
Free interactive boxing glove size lab: measure your hand circumference, match body weight to the right oz (12/14/16 oz) for bag, sparring or fight, plus kids, MMA, women's fit and hand-wrap length. No signup, works offline in your browser.
Boyle's Law Calculator — P₁V₁ = P₂V₂ Solver (Free)
Free Boyle's law calculator: solve P₁V₁ = P₂V₂ for any missing variable. Pressure in Pa, kPa, bar, psi, atm or mmHg; volume in m³, L, mL or ft³. Instant results with full unit conversions. 100% client
BPM Tap Tempo Calculator Online
Free online BPM tap tempo calculator. Find BPM by tapping. Tempo BPM finder, BPM finder tap, online beats per minute calculator, tap tempo finder, BPM counter tap, BPM calculator tap, song tempo calculator, online tap tempo tool, BPM metronome tap.
Bragg\
Bragg's law calculator nλ = 2d·sinθ for X-ray diffraction (XRD): compute λ, d-spacing, θ / 2θ, and order n. Cu Kα, Mo Kα, Co Kα anode presets. Free, 100% client-side.
BMEP Calculator (Brake Mean Effective Pressure) — From Torque, Power & Target
Free BMEP calculator: compute brake mean effective pressure from torque or from power & RPM (2-stroke/4-stroke), plus a reverse mode from a BMEP target to torque & power. Units: bar, psi, kPa. 100% client-side.
Circuit Breaker Size Calculator — What Size Breaker Do I Need?
What size breaker do I need? Enter watts, VA, amps, or HP (120–600V, 1-phase or 3-phase) and get the NEC 240.6 standard breaker size with 125% continuous-load sizing plus a companion wire recommendati
Brew Cost Calculator — Homebrew Cost Per Bottle + "Is It Cheaper?" (Free)
Free homebrew cost calculator: build your batch cost from grain, hops, yeast, water and energy, get cost per bottle / pint / liter, compare vs store beer prices, amortize equipment, and scale recipes. 100% client-side, no signup.
Brewster Angle Calculator (Polarization) — nrtechstudio.com
Compute the Brewster angle θ_B = arctan(n₂/n₁): the incidence angle at which p-polarized reflection becomes zero. Inverse mode: determine the refractive index from a measured Brewster angle. Free, 100% client-side.
Bridge Rectifier Calculator — AC-to-DC Bridge Rectifier Design
Free bridge rectifier design calculator: compute Vpeak, Vdc, ripple, PIV, and filter capacitor needs from transformer specs. Bridge & half-wave modes, 50/60 Hz, 100% client-side.
Broad-Crested Weir Discharge Calculator
Compute discharge (Q), head (H), or crest width (b) of a broad-crested weir. SI & imperial units, 100% client-side, free.
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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.