Free Health Tools & Calculators
Browse 235+ free interactive health calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
4Ts Score Calculator — HIT Pretest Probability
Free 4Ts Score calculator: estimate the pretest probability of Heparin-Induced Thrombocytopenia (HIT) from 4 categories — Thrombocytopenia, Timing, Thrombosis, oTher causes. Live 0–8 score with Low / Intermediate / High interpretation. An educational tool, not a substitute for clinical assessment.
5K Pace Calculator — Target Time to Pace, Splits & Pace Chart
Free 5K pace calculator: convert a 5K target time to pace per km and per mile with cumulative km splits, predict 5K finish time from pace, and browse a 15:00–40:00 pace chart.
6-Minute Walk Test Calculator — Predicted Distance, % Predicted & ATS Protocol | nrtechstudio.com
Free 6-minute walk test (6MWT) calculator: predicted distance from Enright, Troosters & Jenkins reference equations, percent predicted, lower limit of
ABI Calculator — Ankle-Brachial Index (Free, Private)
Free ankle-brachial index (ABI) calculator. Enter dorsalis pedis, posterior tibial and brachial systolic pressures — get per-leg ABI, interpretation ranges, and educational next steps. 100% client-side, no data leaves your browser.
ACFT Score Calculator — Army Combat Fitness Test (6 Events)
Free ACFT score calculator: enter your 6 event results plus age and gender to estimate your Army Combat Fitness Test score (0–600), with a 60-point pass/fail gate per event. Simplified from published standards.
Adjusted Age Calculator for Premature Babies
Free adjusted age (corrected age) calculator for premature babies. Enter birth date and gestational age at birth to get chronological vs adjusted age in years/months/days, total weeks, and the catch-up date.
Adjusted Weight Calculator — IBW, AdjBW & Amputation Weight Estimates
Educational adjusted body weight calculator: compute IBW (Devine formula), AdjBW = IBW + 0.4×(actual−IBW) for drug dosing in obesity, and pre-amputation weight estimates from body-segment frac
Adrenal Washout (CT) Calculator — Calculate Absolute & Relative Washout
Free adrenal washout calculator: compute absolute washout and relative washout from CT HU values (unenhanced, portal venous, delayed 15 min) for adrenal lesion evaluation. A radiology education tool.
AFT Calculator — Army Fitness Test Score Calculator (2025 Standards) | nrtechstudio.com
Free Army Fitness Test (AFT) calculator: score all 5 events (deadlift, hand-release push-up, sprint-drag-carry, plank, 2-mile run) against the officia
Age-Adjusted D-Dimer Calculator — Cutoff by Age (FEU & DDU)
Free age-adjusted D-dimer cutoff calculator: age × 10 µg/L FEU for patients over 50, 500 µg/L at 50 or below. Converts µg/L, ng/mL, mg/L and FEU/DDU. 100% client-side educational tool.
AI Water Footprint Calculator — Per-Query Range Estimate
Estimate your daily AI usage water footprint (mL–L range) from verified literature: the UC Riverside 'Making AI Less Thirsty' study, Microsoft sustainability reports, and IEA data. Always shown as a range, not a single figure.
Air Force PT Calculator — USAF PFRA Score Calculator (2026 Standards)
Free USAF Physical Fitness Readiness Assessment (PFRA) score calculator. Enter push-ups, core, 2-mile run or HAMR, and waist-to-height ratio to estimate your score out of 100 by age group and gender. Unofficial training aid.
Albumin/Globulin Ratio Calculator — A/G Ratio + Inverse Solver | nrtechstudio.com
Free A/G ratio calculator: albumin/globulin ratio from total protein and albumin, unit conversion g/dL to g/L, inverse solver for albumin or globulin
Aldrete Score Calculator — Post-Anesthesia Recovery & PACU Discharge Score | nrtechstudio.com
Free Aldrete score calculator: interactive 5-criterion postanesthetic recovery scoring (original colour and modified SpO2 versions), blood-pressure de
Allele Frequency Calculator (Hardy-Weinberg)
Free allele frequency calculator: enter genotype counts (AA, Aa, aa) to get p and q, expected Hardy-Weinberg genotype frequencies (p^2, 2pq, q^2), and a chi-square goodness-of-fit test (df=1) with p-v
Amoxicillin Pediatric Dosage Calculator (Educational Estimator) — nrtechstudio.com
Educational pediatric amoxicillin dose estimator by weight: mg per dose and mL per dose for common suspensions (125/5, 200/5, 250/5, 400/5), standard vs high-dose regimens. Not medical advice — final dosing by a doctor or pharmacist.
ANC Calculator Without Bands — Absolute Neutrophil Count
Free ANC calculator without bands: compute Absolute Neutrophil Count from WBC and segmented neutrophils (segs), with category, gauge, formula breakdown, optional with-bands comparison, and FAQ. Educational tool.
Animal Mortality Rate Calculator — Per-Period, Annualized & Life Table (Free)
Free animal mortality rate calculator for livestock, poultry and lab animals. Enter starting population and deaths to get mortality rate, survival rate, annualized mortality, a simple life table and g
APACHE II Score Calculator — ICU Severity Score + Mortality Estimate
Free APACHE II Score calculator: compute ICU disease severity score from 12 physiologic variables + age + chronic health (total 0–71) with per-variable breakdown, gauge, and Knaus mortality estimate table as context. Educational tool, not a substitute for clinical judgment.
APFT Score Calculator — Legacy Army Physical Fitness Test (300 pts)
Free APFT score calculator: enter push-ups, sit-ups and 2-mile run plus age and gender to estimate your legacy Army Physical Fitness Test score (0–300) with the 60-point pass gate per event. Simplified from published FM 7-22 standards.
Apgar Score Calculator — Newborn 1-Minute & 5-Minute Assessment | nrtechstudio.com
Free Apgar score calculator: score a newborn's Appearance, Pulse, Grimace, Activity, and Respiration (0-2 each) at 1, 5, and 10 minutes. Total 0-10 wi
APRI Calculator — AST to Platelet Ratio Index for Liver Fibrosis
Free APRI score calculator: estimate liver fibrosis likelihood from AST and platelet count. Formula breakdown, gauge, worked examples, and APRI vs FIB-4 explained. Educational use only.
Army Body Fat Calculator — AR 600-9 Tape Test
Compute body fat percentage per U.S. Army AR 600-9 with the official tape test formula (male & female), cm/inch conversion, and passing standards per age group.
Arterial Age Calculator — Heart Age from 10-Year ASCVD Risk (PCE)
Free arterial age calculator: enter 9 risk factors (age, sex, race, total & HDL cholesterol, systolic blood pressure, BP medication, diabetes, smoking) to estimate your arterial age vs chronological age from 10-year ASCVD risk using the 2013 ACC/AHA Pooled Cohort Equations. 100% in-browser. Educatio
ASVAB Score Calculator — AFQT Percentile + Line Scores (All Branches) | nrtechstudio
Free ASVAB score calculator: get your AFQT percentile with the official PAY97 method, plus line scores for Army, Navy, Air Force, Marines & Coast Guar
AUDIT Alcohol Test — WHO Screening Calculator (Full AUDIT + AUDIT-C)
Free WHO AUDIT alcohol screening test: answer the 10 official AUDIT questions (score 0-40, WHO risk zones) or the 3-question AUDIT-C (score 0-12, sex-
Baby Growth Percentile Calculator — WHO Length-for-Age & Weight-for-Length (0–24 Months) | nrtechstudio.com
Compute length-for-age and weight-for-length percentiles and z-scores for babies 0–24 months using the official WHO Child Growth Standards LMS tables.
Baby Percentile Calculator — WHO Weight-for-Age (0–24 Months)
Free baby weight percentile calculator using the official WHO Child Growth Standards (LMS method). Enter age, weight and sex to get percentile, z-score and growth category for babies 0–24 months.
Baby Sleep Schedule Calculator — Wake Windows by Age, Naps & Bedtime
Free baby sleep schedule calculator: generate a nap schedule by age with wake windows, explore wake windows 0–24 months, predict nap transitions (3→2→1), solve bedtime in reverse, and check total sleep vs AAP ranges. 100% client-side, no signup.
Baby's Milk Intake Calculator by Weight — How Much Milk Should Baby Drink
Calculate how much milk your baby needs per day by body weight (mL/kg): 0–6 months ~150 mL/kg/day (range 120–180), 6–12 months 500–700 mL/day. Includes per-feed amounts and mL to oz conversion. Educational guide, not medical advice.
Bacteria Growth Calculator — Doubling Time, OD600 & Growth Curve | NR Tech Studio
Free bacteria growth calculator: exponential growth N = N0 x 2^(t/g), doubling time from cell counts, time to reach a target population, OD600 to cells/mL estimate, and lag/log/stationary/death growth
Barthel Index Calculator — ADL Score (0–100 & 0–20 Scales)
Free Barthel Index calculator for activities of daily living (ADL). Score all 10 items on the original 0–100 scale (Mahoney & Barthel 1965) or the 0–2
Basal Area Calculator — Tree Basal Area, m²/ha & Stocking | nrtechstudio
Free basal area calculator: enter DBH to get per-tree basal area (cm², m², in², ft²), aggregate any fixed-area plot to m²/ha and ft²/acre, and estimate stocking with Reineke SDI. 100% client-side.
BASDAI Calculator — Bath Ankylosing Spondylitis Disease Activity Index
Free BASDAI calculator: answer 6 visual-analogue-scale questions (0-10) and get your Bath Ankylosing Spondylitis Disease Activity Index score, interpretation (active vs low disease activity), and question-by-question breakdown.
Batting Strike Rate Calculator — Cricket SR, Runs Needed & Balls Allowed
Free cricket batting strike rate calculator. Compute strike rate from runs and balls faced, work out runs needed for a target strike rate, or balls allowed at a target rate — with format context (Test, ODI, T20).
Beighton Score Calculator — 9-Point Joint Hypermobility Test
Free Beighton score calculator: the 9-point joint hypermobility screening test (5 maneuvers, bilateral scoring). Age-adjusted cutoffs (2017): ≥6 pre-p
Benadryl Dosage Calculator for Dogs — Diphenhydramine mg by Weight + Tablet Guide
Estimate Benadryl (diphenhydramine) dosage for dogs by weight: 1 mg per pound every 8-12 hours, converted to 25 mg tablets and liquid mL. Educational estimate, not veterinary advice.
Bench Press Calculator — 1RM Max, Plate Loader & Strength Ratio
Free bench press calculator: estimate your 1RM max from weight × reps with 4 formulas (Epley, Brzycki, Lombardi, O'Conner), % of 1RM training table, plate loader per side, and bodyweight strength ratio.
Bench Press Pyramid Calculator — 1RM Pyramid Workout Generator
Generate a bench press pyramid workout from your 1RM. Ascending, descending and full pyramid tables with %1RM x reps, set volume, total volume and rest times.
Bicarbonate Deficit Calculator — Metabolic Acidosis HCO3⁻ Correction Estimate
Free bicarbonate deficit calculator: (target − measured) × weight × distribution factor, half-dose estimate, mL of 8.4%/7.5%/4.2% NaHCO3 and infusion
Bike Cadence & Speed Calculator — Cadence ↔ Speed via Gears
Convert bike cadence (rpm) to speed (km/h, mph) or find the cadence you need for a target speed, using chainring, cassette cog and wheel size.
Bike Gear Calculator — Gear Inches, Development & Gain Ratio
Free bike gear ratio calculator: enter chainring, cog and wheel size to get gear inches, development, gain ratio and a speed-at-cadence table. Modern take on the classic gear calculator.
Bike Speed Calculator — Speed ↔ Pace ↔ Time (Free)
Free bike speed calculator: convert speed to pace (2:00/km style), pace to speed, average speed from distance & time, and ride-time estimates. km/h & mph, min/km & min/mi. 100% client-side.
Bird Age Calculator — Estimate Your Bird's Age (Budgie, Cockatiel, Lovebird, Canary)
Free bird age calculator: estimate your budgie, cockatiel, lovebird or canary's age from iris, cere, beak and plumage signs. Honest ranges, not fake exact ages.
Birthweight Percentile Calculator — INTERGROWTH-21st by Gestational Age
Free birthweight percentile calculator using the INTERGROWTH-21st newborn size standards (LMS method). Enter gestational age, birthweight and sex to get percentile, z-score and SGA/AGA/LGA classification.
Bishop Score Calculator: Cervical Readiness for Induction of Labor | nrtechstudio.com
Free Bishop score calculator: score the five components (dilation, effacement, station, consistency, position) on the 0-13 scale, see the favorable/in
Bladder Volume Calculator — Estimate Bladder Volume from Ultrasound (Ellipsoid Formula)
Bladder volume calculator from ultrasound results: V = 0.52 × D1 × D2 × D3. Interpretation of post-void residual (PVR) normal/borderline/abnormal and functional capacity estimates. Educational tool, not a diagnosis.
BMI Calculator for Women — BMI, Healthy Weight Range & Body Fat Estimate
Free BMI calculator designed for women. Get your BMI with WHO category, healthy weight range for your height, an estimated body fat % (Deurenberg formula), and age-aware context. 100% private — runs in your browser.
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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.