Free Health Tools & Calculators
Browse 235+ free interactive health calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
Protein Concentration Calculator — A280, Bradford/BCA, Unit Converter & Dilution
Free protein concentration calculator: A280 Beer–Lambert with a 10-protein extinction-coefficient database, Bradford/BCA standard-curve fit with R², mg/mL ↔ µM converter and C1V1 dilution planner. 100% client-side.
Protein Molecular Weight Calculator — Sequence to MW, Extinction Coefficient | nrtechstudio
Free protein molecular weight calculator: paste an amino acid sequence to get MW in Da/kDa, extinction coefficient ε280 (Pace), A280 of 1 mg/mL, composition chart, unit converter and fusion-tag adjuster. 100% client-side.
Push-Ups Calorie Calculator — Calories Burned Per Rep & Per Workout
Free push-up calorie calculator: enter reps or workout time plus body weight and intensity to estimate calories burned, calories per push-up, and food equivalents. MET values verified from the Compendium of Physical Activities. 100% private, no signup.
qSOFA Score Calculator — Quick Sepsis Screening (Sepsis-3) | nrtechstudio
Free qSOFA calculator (Seymour et al., JAMA 2016, Sepsis-3): respiratory rate ≥22/min, altered mentation (GCS <15), systolic BP ≤100 mmHg — score 0
QTc Calculator — Corrected QT Interval (Bazett, Fridericia, Framingham, Hodges)
Free QTc calculator: correct the QT interval for heart rate with four formulas — Bazett, Fridericia, Framingham (Sagie) and Hodges. Sex-specific inter
RCRI Calculator — Revised Cardiac Risk Index for Surgery (Educational) — NR Tech Studio
Free RCRI calculator: estimate perioperative cardiac risk for noncardiac surgery from the 6 Revised Cardiac Risk Index predictors (Lee 1999), with risk classes I–IV, derivation and validation cohort rates, contemporary re-estimates, and ACC/AHA guideline context. Educational tool — not medical advic
SAPS II Score Calculator — ICU Severity Score + Mortality Estimate
Free SAPS II Score calculator: calculate the Simplified Acute Physiology Score II (Le Gall 1993) from 12 physiologic variables + age + chronic disease + admission type (total 0–163) with a transparent per-variable point breakdown and logistic-regression mortality estimate. Educational tool, not medical advice.
Shannon Index Calculator — Shannon Diversity Index (H'), Evenness & Simpson
Free Shannon index calculator: compute Shannon diversity index H' = -sum(p_i * ln(p_i)), Pielou evenness J', species richness, and Simpson index from species counts. Compare two communities. 100% clie
Shock Index Calculator — SI, Modified Shock Index & Age SI
Free shock index calculator: enter heart rate, systolic and diastolic blood pressure to get the shock index (HR/SBP), mean arterial pressure, modified
Sleep Cycle Calculator: Best Bedtime & Wake-Up Times (90-Minute Cycles)
Free sleep cycle calculator: enter the time you must wake up and get the best bedtimes (or enter bedtime and get the best wake-up times) based on 90-minute sleep cycles. Includes sleep duration by age, sleep-stage explainer, and nap planner. 100% client-side — your data never leaves your browser.
Smoking Recovery Timeline — Recovery Timeline After Quitting Smoking
Enter your quit date and see where you stand on the health recovery timeline: from 20 minutes to 15 years, based on American Cancer Society data.
Standard Drink Calculator — Beer, Wine & Spirits (US NIAAA)
Free standard drink calculator: convert any beer, wine, or spirits serving to US standard drinks (14 g pure alcohol, NIAAA definition). Custom volume + ABV, session total, and beer/wine/shot equivalents. Educational tool.
Steps to Calories Calculator — Convert Steps to kcal (with Height)
Convert step count to calories burned. Enter steps + body weight (height optional) for a stride-based estimate, or reverse it: calories goal to steps needed. Free, no sign-up.
Stillbirth Risk Factor Calculator (Educational)
Stillbirth risk factor explainer (CDC, Lancet, JAMA): checklist of 10 documented risk factors with educational context, pregnancy warning signs, and a guide for discussing with your doctor or midwife.
STOP-Bang Calculator — Sleep Apnea Risk Screening Tool
Free STOP-Bang calculator: answer 8 yes/no questions to screen for obstructive sleep apnea risk (low, intermediate, high) with the validated Chung et al. scoring. Screening aid only, not a diagnosis.
Sugar Intake Calculator — Daily Limit, WHO & AHA Guidelines | nrtechstudio
Free sugar intake calculator: find your daily limit from WHO (<10% of calories, ideal <5%) and AHA guidelines (men 36 g, women 25 g), convert gr
TIMI STEMI Score Calculator — 30-Day Mortality Estimate (Morrow 2000) — NR Tech Studio
TIMI score calculator for STEMI (Morrow 2000): score 8 bedside variables, 0–14 point total, 30-day mortality estimate, risk categories, full mortality table, and clinical FAQ. Educational tool — not medical advice.
TIMI Risk Score Calculator for UA/NSTEMI — 14-Day Composite Risk (Antman 2000) — NR Tech Studio
TIMI risk score calculator for unstable angina/NSTEMI (Antman 2000): 7 variables at 1 point each, total 0–7, 14-day composite risk estimates, risk table, GRACE/HEART comparison, and clinical FAQ. Educational tool — not medical advice.
Tinetti (POMA) Calculator — Elderly Fall Risk Test
Interactive Tinetti POMA (Performance Oriented Mobility Assessment) calculator: 16 balance and gait observation items, 0–28 score, real-time subtotals, and fall risk categories.
ACR TI-RADS Calculator — Thyroid Nodule Classification from Ultrasound
ACR TI-RADS (2017) calculator: score 5 thyroid nodule ultrasound features, determine TR1–TR5 level, FNA & ultrasound follow-up thresholds, plus a multi-nodule tracker.
Transferrin & Iron Studies Calculator — TSAT, UIBC, Ferritin
Free transferrin & iron studies calculator: calculate transferrin saturation (TSAT) and UIBC from serum iron & TIBC, convert units µg/dL ⇄ µmol/L, integrated TSAT + ferritin interpretation panel. 100% client-side.
Tree Benefits Calculator — CO2, Stormwater, Cooling & Air Quality
Estimate a tree's annual ecosystem benefits i-Tree style: CO2 sequestered and stored (Jenkins 2003 biomass), stormwater intercepted (Xiao & McPherson), cooling energy saved, and air pollutants removed
Tree Diameter Calculator (DBH) — Measure, Convert & Basal Area
Free tree diameter (DBH) calculator: convert tape circumference to diameter, diameter to circumference and basal area, combine multi-stem trunks, and estimate plot basal area per acre. Imperial and me
Trihybrid Cross Punnett Square Calculator — 64-Box Grid, 27:9:9:9:3:3:3:1
Free trihybrid cross Punnett square calculator: enter two parent genotypes (AaBbCc x AaBbCc), get the 64-box grid, 27:9:9:9:3:3:3:1 phenotypic ratio, exact genotype probabilities, and a phenotype-prob
Urine Anion Gap (UAG) Calculator — NAGMA Interpretation & NH4+ Estimation
Urine anion gap calculator (UAG = (U_Na + U_K) − U_Cl): normal anion gap metabolic acidosis interpretation, urinary ammonium excretion estimation, NAGMA decision tree, RTA differential table, and primary-literature-based FAQ.
Urine Output Calculator — mL/kg/hr Rate + KDIGO AKI Criteria
Free urine output calculator: compute mL/kg/hr rate, convert mL/hr and mL/24 hr, check oliguria/anuria criteria and KDIGO 2012 AKI staging, plus hourly serial monitoring. 100% client-side, educational — not medical advice.
URR (Urea Reduction Ratio) Calculator + Kt/V Estimate — nrtechstudio.com
Calculate Urea Reduction Ratio (URR) from pre- and post-hemodialysis BUN, KDOQI ≥65% target interpretation, spKt/V estimate, and the Daugirdas formula. Free, 100% client-side.
VA Disability Calculator 2026 — Combined Ratings, Bilateral Factor & Pay
Free 2026 VA disability calculator: combined ratings (38 CFR 4.25), bilateral factor (38 CFR 4.26), what-if claim planner, and 2026 monthly pay tables. 100% client-side.
Vaccine Efficacy Calculator (VE) — 2×2 Table + Confidence Interval
Compute vaccine efficacy (VE) from a 2×2 table: attack rate, relative risk, 95% confidence interval (Katz method), ARR, NNV, and statistical tests. Free, 100% runs in your browser.
Vapor Pressure Deficit (VPD) Calculator — kPa, Leaf VPD & Grow Chart
Free vapor pressure deficit calculator: air & leaf VPD in kPa from temperature and humidity (Tetens equation), growth-stage zones (seedling, veg, flower), dew point, target humidity, and a full VPD ch
Vegetable Yield Calculator — Harvest Estimate per Plant & Bed Size
Estimate your vegetable garden harvest: yield-per-plant ranges for 22 common vegetables, plants-from-bed-size, totals in lb and kg, plus a succession planting guide.
VLDL & Friedewald Lipid Panel Calculator — VLDL, LDL, Non-HDL + Ratios
VLDL & Friedewald lipid panel calculator: compute VLDL, LDL (Friedewald), non-HDL, and TG/HDL, total/HDL, LDL/HDL ratios from total cholesterol, HDL, and triglycerides. mg/dL↔mmol/L toggle, TG≥400 validity flag, NCEP ATP III target table, and FAQ.
Pregnancy VTE Risk Calculator (RCOG 37a) — Antenatal & Postnatal
Venous thromboembolism (VTE) risk assessment in pregnancy per RCOG Green-top Guideline No. 37a: antenatal & postnatal risk factor checklist, automatic stratification, weight-based LMWH dose table, and FAQ. Educational tool, not medical advice.
Warsaw Method Calculator (FPU) — Insulin Dose for Fat & Protein
Free Warsaw Method calculator: compute fat-protein units (FPU), carbohydrate equivalent, extended insulin bolus dose and bolus duration for high-fat / high-protein meals from grams of fat, grams of protein and your insulin-to-carb ratio. Educational estimate only — not medical advice.
Water Deficit Calculator — Free Water Deficit, Sodium Deficit & Corrected Na
Free water deficit calculator (Adrogue-Madias): estimate TBW, free water deficit in hypernatremia, sodium deficit and 3% saline planning in hyponatremia, and Katz corrected sodium for hyperglycemia. 100% in-browser, educational only.
Water Intake Calculator — How Much Water Should You Drink a Day? (Free)
Free daily water intake calculator: personalized hydration target in ml, ounces, liters, glasses and bottles from your weight, activity, climate, exercise, pregnancy & breastfeeding. Includes a drinking schedule planner. 100% client-side, no signup.
Weight Loss Percentage Calculator — % Lost & Newborn Tracker
Calculate your weight loss percentage from start weight to current weight. Includes a newborn mode (birth-weight loss % with clinical 7–10% guidance bands), milestone weights, goal-progress tracking, and step-by-step breakdown.
Weight Watchers Points Calculator — PointsPlus, ProPoints & Original Points
Educational Weight Watchers points calculator: calculate PointsPlus (US), ProPoints (UK), and Original Points (pre-2011) from nutrition labels. Published legacy formulas, 100% offline, with full calculation breakdown.
Wells Score Calculator for Pulmonary Embolism (PE) — 7 Criteria
Free Wells PE score calculator: 7 weighted Wells et al. criteria, score 0–12.5, 2-tier & 3-tier models, pretest prevalence, and the D-dimer vs CTPA diagnostic pathway. 100% client-side, educational tool.
Wind Turbine Profit Calculator — Revenue, Payback, NPV, IRR, LCOE
Free wind turbine profit calculator: estimate annual energy production, revenue, payback period, NPV, IRR and LCOE for one turbine or compare two scenarios. Honest assumptions you can edit.
Winning Percentage Calculator — W/L/T with 3 Tie Methods
Free winning percentage calculator: enter wins, losses and ties to get win% with standard (ties as half-win), ties-excluded, and soccer-style (3 points per win) methods.
Winter's Formula Calculator: Expected pCO2 in Metabolic Acidosis
Free Winter's formula calculator: compute expected pCO2 from HCO3 (1.5 × HCO3 + 8 ± 2 mmHg), check adequacy of respiratory compensation in metabolic acidosis, reference table, and FAQ. 100% client-side.
Vitamin D Calculator — Dose, Sunlight & 25(OH)D Estimator
Free vitamin D calculator: estimate your D3 dose from 25(OH)D blood levels and weight, plus sunlight estimator, food intake checker and IU to mcg converter.
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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.