Developer Utilities
Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.
Developer Utilities
Mulch calculator
cubic yards and bags from bed area and depth, free
POST /home/mulch$0.002Developer Utilities
Paint quantity calculator
liters from wall area or room size, free
POST /home/paint-needed$0.002Developer Utilities
Rafter length calculator
common rafter from span, free
POST /home/rafter-length$0.002Developer Utilities
Retaining wall block calculator
blocks and courses from length, free
POST /home/retaining-wall-blocks$0.002Developer Utilities
Tile grout calculator
kg from tile size, joint width and area, free
POST /home/tile-grout$0.002Developer Utilities
Room wall area calculator
net paintable walls from L×W×H, free
POST /home/wall-area$0.002Developer Utilities
Cost per day calculator
annual price to daily, weekly, monthly, free
POST /life/cost-per-day$0.002Developer Utilities
Cost per use calculator
price divided by expected uses, free
POST /life/cost-per-use$0.002Developer Utilities
Emergency fund calculator
months of essential expenses, free
POST /life/emergency-fund$0.002Developer Utilities
Hourly to salary converter
annual pay from wage, hours, weeks free
POST /life/hourly-to-salary$0.002Developer Utilities
Reverse sales tax calculator
pre-tax price from tax-inclusive total, free
POST /life/reverse-sales-tax$0.002Developer Utilities
Rule of 72 calculator
years to double at a growth rate, free
POST /life/rule-of-72$0.002Developer Utilities
Geometric sequence calculator
n-th term and finite sum, free
POST /math/geometric-sequence$0.002Developer Utilities
Pell number calculator
P_n = 2P_{n-1}+P_{n-2}, free bigint
POST /math/pell-number$0.002Developer Utilities
Perfect square checker
n-th square and isqrt test, free
POST /math/square-number$0.002Developer Utilities
Sum of first n cubes
1³+…+n³ = (n(n+1)/2)², free
POST /math/sum-of-cubes$0.002Developer Utilities
Superfactorial calculator
product of first n factorials, free bigint
POST /math/superfactorial$0.002Developer Utilities
Telescoping series sum
Σ 1/(k(k+1)) = n/(n+1), free
POST /math/telescoping-sum$0.002Developer Utilities
Tetrahedral number calculator
n-th Te_n = n(n+1)(n+2)/6, free
POST /math/tetrahedral-number$0.002Developer Utilities
Acceleration calculator
a = Δv/t average acceleration, free
POST /mech/acceleration$0.002Developer Utilities
Circular motion velocity calculator
v = 2πr/T tangential speed, free
POST /mech/circular-velocity$0.002Developer Utilities
Free fall time calculator
t = √(2d/g) from rest, free
POST /mech/free-fall-time$0.002Developer Utilities
Friction force calculator
F = μ·N from coefficient and normal force, free
POST /mech/friction-force$0.002Developer Utilities
Inelastic collision calculator
common final velocity v_f, free
POST /mech/inelastic-collision$0.002Developer Utilities
Lever calculator
effort force for a balanced lever, free
POST /mech/lever$0.002Developer Utilities
Gravitational potential energy calculator
PE = m·g·h in joules, free
POST /mech/potential-energy$0.002Developer Utilities
Projectile max height calculator
H = v₀² sin²θ / (2g), free
POST /mech/projectile-max-height$0.002Developer Utilities
RPM to linear speed calculator
v = 2πr·(rpm/60) rim speed, free
POST /mech/rpm-to-linear$0.002Developer Utilities
Spring potential energy calculator
PE = ½kx² in joules, free
POST /mech/spring-potential-energy$0.002Developer Utilities
Velocity components calculator
horizontal vx and vertical vy, free
POST /mech/velocity-components$0.002Developer Utilities
Weight calculator
W = m·g force in newtons, free
POST /mech/weight-force$0.002Developer Utilities
Abundant number checker
aliquot sum and abundance amount, free
POST /numth/abundant-number$0.002Developer Utilities
Carmichael function calculator
compute λ(n) for any positive integer
POST /numth/carmichael-function$0.002Developer Utilities
Chinese remainder theorem solver
solve x ≡ ai mod ni, free
POST /numth/chinese-remainder$0.002Developer Utilities
Collatz conjecture calculator
3n+1 sequence, steps and peak, free
POST /numth/collatz$0.002Developer Utilities
Coprime checker
test gcd(a,b)=1 and return the gcd, free
POST /numth/coprime-checker$0.002Developer Utilities
Kaprekar number checker
square splits that add back to n, free
POST /numth/kaprekar-number$0.002Developer Utilities
Nth prime calculator
find the n-th prime number, free
POST /numth/nth-prime$0.002Developer Utilities
Prime factorization calculator
factor any integer into prime powers
POST /numth/prime-factorization$0.002Developer Utilities
Primitive root calculator
smallest generator mod prime p, free
POST /numth/primitive-root$0.002Developer Utilities
Smith number checker
digit sum vs prime-factor digit sum, free
POST /numth/smith-number$0.002Developer Utilities
Double slit calculator
fringe spacing Δy = λL/d, free
POST /optics/double-slit$0.002Developer Utilities
Focal length calculator
lens f from object & image distance, free
POST /optics/focal-length$0.002Developer Utilities
Refractive index calculator
n = c/v or speed from n, free
POST /optics/refractive-index$0.002Developer Utilities
Thin lens calculator
image distance & magnification, free
POST /optics/thin-lens$0.002Developer Utilities
Sound level distance calculator
inverse-square dB from one range, free
POST /phys/decibel-distance$0.002Developer Utilities
Frequency calculator
f = v / λ from wave speed and wavelength, free
POST /phys/frequency$0.002Developer Utilities
String harmonic frequency calculator
f₁ = (1/2L)√(T/μ), free
POST /phys/harmonic-string$0.002Developer Utilities
Bayes theorem calculator
posterior from prior, sensitivity, FPR, free
POST /prob/bayes-theorem$0.002Developer Utilities
Binomial probability calculator
P(X=k), CDF, mean, variance, free
POST /prob/binomial-distribution$0.002Developer Utilities
Lottery odds calculator
match m of r in n-choose-r, optional bonus, free
POST /prob/lottery-odds$0.002Developer Utilities
Negative binomial calculator
P(r-th success on trial k), free
POST /prob/negative-binomial$0.002Developer Utilities
Factor of safety calculator
n = ultimate strength / working stress, free
POST /sci/factor-of-safety$0.002Developer Utilities
Poisson's ratio calculator
ν = −ε_lateral/ε_axial from strains, free
POST /sci/poisson-ratio$0.002Developer Utilities
Engineering strain calculator
ε = ΔL/L₀ as ratio and percent, free
POST /sci/strain$0.002Developer Utilities
Correlation coefficient calculator
Pearson r for two series, free
POST /stat/correlation$0.002Developer Utilities
Mean absolute deviation calculator
MAD about the mean, free
POST /stat/mean-absolute-deviation$0.002Developer Utilities
Percentile calculator
k-th percentile & rank by linear, free
POST /stat/percentile$0.002Developer Utilities
Standard deviation calculator
population & sample σ, variance, free
POST /stat/standard-deviation$0.002Developer Utilities
Convert to alternating case
aLtErNaTiNg text converter, free
POST /str/alternating-case$0.002