🧮Calculators
Calculators cover finance, health, math, physics, engineering and everyday life: interest and loans, net salary, BMI, rule of three, conversions and more. Results are informational and educational — for important decisions, confirm with a professional and official sources.
2826 tools
Apgar Score
Compute newborn Apgar score (5 criteria × 0-2 = 0-10).
Estimated Due Date
Compute estimated due date using Naegele rule: LMP + 280 days.
Gestational Age
Compute gestational age in weeks/days from LMP to today.
Cable Voltage Drop
Compute voltage drop ΔV = 2·ρ·L·I/A in cable.
Minimum Cable Size (NBR 5410)
Recommend minimum copper cable size (mm²) for residential single-phase circuit by current.
Bricks per Wall Calculator
Compute number of bricks needed for a wall by dimensions and brick type.
Wall Concrete Volume
Compute concrete volume m³ + cement/sand/gravel estimates for a wall.
Paint Coverage Calculator
Compute paint liters needed for an area, given coverage per liter and coats.
Tile Quantity Calculator
Compute tile quantity for an area given tile dimensions and 10% waste.
SaaS Magic Number
Compute SaaS Magic Number = (ARR_current − ARR_prev) × 4 / S&M_prev.
Net Dollar Retention
Compute NDR = (start ARR + expansion − churn − contraction) / start ARR × 100.
SaaS Quick Ratio
Compute SaaS Quick Ratio = (new + expansion) / (churn + contraction).
SaaS Rule of 40
Compute Rule of 40 = revenue growth % + operating margin %.
Burn Multiple
Compute Burn Multiple = net burn / new ARR. <1 excellent, >2 inefficient.
Creatinine Clearance (Cockcroft-Gault)
Compute creatinine clearance by Cockcroft-Gault formula.
Plasma Osmolarity
Estimate plasma osmolarity: 2·Na + glucose/18 + BUN/2.8.
Anion Gap Calculator
Compute anion gap: (Na + K) − (Cl + HCO3). Normal: 8-16 mEq/L.
Henderson-Hasselbalch Buffer pH
Compute buffer pH: pH = pKa + log10(base/acid).
Hydrostatic Pressure
Compute hydrostatic pressure P = ρ·g·h.
Projectile Range Calculator
Compute projectile horizontal range from v₀, angle and initial height.
Projectile Time of Flight
Compute projectile total time of flight including initial height.
Weight on Other Planets
Compute your weight across Solar System bodies (Mercury to Sun).
Cubic Equation Solver
Solve cubic ax³+bx²+cx+d=0 by Cardano formula. Shows real and complex roots.
Big Factorial (BigInt)
Compute n! up to 1000 with BigInt and show full result + digit count.
Arrangements A(n,k)
Compute arrangements A(n,k) (same as permutations).
Euler Totient Function φ(n)
Compute Euler totient φ(n).
GCD with Bezout Coefficients
Compute gcd(a,b) and Bezout coefficients x,y where a·x + b·y = gcd.
Perfect Number Checker
Check if n is a perfect number; list its divisors.
Complex Numbers Operations
Add, subtract, multiply and divide two complex numbers; includes modulus and argument.
Eigenvalues 2×2 Matrix
Compute eigenvalues of 2×2 matrix solving λ² − (a+d)λ + (ad−bc) = 0.
Determinant of 4×4 Matrix
Compute determinant of 4×4 matrix by Laplace expansion.
Molar Mass Calculator
Compute molar mass of a chemical formula (H2O, C6H12O6, NaCl) by summing atomic weights. 50 most-used elements.
Speed of Light Calculator (E=mc²)
Apply formulas involving c (speed of light): mass-energy equivalence (E=mc²) and light travel time over a distance.
Percent Error Calculator
Compute percent and absolute error between an experimental value and a theoretical/expected one.
Measurement Uncertainty (Propagation) Calculator
Compute propagated uncertainty in sum, product, division and power, given source uncertainties (RSS rule).
Bacterial Growth Calculator
Compute bacteria count after N divisions (N = N₀ × 2^t/td) — where td is doubling time. For microbiology and exponential growth.
Drug Dose Calculator (per kg)
Compute total drug dose (mg) from mg/kg posology and patient weight. Not medical advice.
IV Drip Rate Calculator
Compute drip rate (drops/min) of IV solution from volume, time and drop factor (20 gtt/mL = standard). For nursing.
Shipping Cost Calculator
Estimate shipping cost from weight, distance, $/kg/km and flat fee. Simple model for sales and e-commerce.
ICMS-ST Tax Substitution Calculator
Compute Brazilian ICMS-ST from goods value, MVA, internal and interstate tax rates. Official invoice formula.
PIS & COFINS Tax Calculator
Compute Brazilian PIS (0.65% / 1.65%) and COFINS (3% / 7.6%) on revenue. For common tax regime.
Brazilian Personal Income Tax Calculator (Monthly)
Compute Brazilian monthly IRPF using the progressive 2024/2025 table (5 brackets).
Sales Commission Calculator
Compute sales commission with progressive targets: lower % until quota, higher % after. Shows commission and total earned.
Car Rental Cost Calculator
Estimate total car-rental cost: daily × days + extra-km + fuel + fees. Compares options.
Heart Rate Zones Calculator (Karvonen)
Compute the 5 training zones (recovery, warmup, aerobic, threshold, max) using the Karvonen formula. Age + resting HR.
Tabata Time Calculator
Compute total Tabata workout time: 8 rounds × (20s on + 10s off) by default. Configurable rounds, on, off, blocks.
Pomodoro Sessions Calculator
Compute total time for a Pomodoro session: 25 min focus + 5 min break, with long break every 4 rounds.
M/M/1 Queue (Cinema) Calculator
Apply M/M/1 queue theory to a cinema: given arrival (λ) and service (µ) rates, compute mean queue time and counter utilization.
Queue Wait Time Estimator
Estimate wait time in a queue: position × mean service time. Accounts for parallel servers (counters).
Star Distance (Light-years) Calculator
Convert light-years to other units (parsec, AU, km) and compute when light was emitted (Sirius = 8.6 years ago).
Erlang C Call-Center Calculator
Compute number of agents needed in a call center using the Erlang C formula — given traffic, service level and mean call time.
Resource Utilization Calculator
Compute resource utilization (CPU, machine, person) — busy time / total available time. Shows efficiency and idle time.
Overtime Pay Calculator (BR CLT)
Compute overtime (50% normal, 100% Sun/holiday, 20% night). Standard Brazilian CLT for monthly employees.
PL (Net Price as % of Sales) Calculator
Compute the Net Price (PL) breakdown over sales: cost, expenses, profit. Shows final PL and net margin.
ROAS (Return on Ad Spend) Calculator
Compute ROAS = revenue / ad cost. Shows break-even and flags whether the campaign was profitable (ROAS > 1).
CAC (Customer Acquisition Cost) Calculator
Compute CAC = (marketing + sales costs) / customers acquired. Compares to LTV to validate business health (LTV/CAC ≥ 3).
Truncated Cone Volume Calculator
Compute volume and lateral area of a truncated cone: V = (π·h/3)·(R²+r²+R·r). For containers and construction.
Pyramid Volume Calculator
Compute volume of a regular pyramid (square base): V = (base area × height) / 3. Also shows lateral and total area.
Hexagonal Prism Volume Calculator
Compute volume and area of a regular hexagonal prism: V = (3√3/2)·a²·h. For 3D geometry, packaging, crystallography.
Truncated Cone Area Calculator
Compute the total surface area of a truncated cone (R, r, h): A = πR² + πr² + π(R+r)·g, where g is the slant.