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Modular Type Scale Calculator

A **modular type scale** is a typographic technique popularised by Tim Brown in *A List Apart* (2011): multiply a base font size by a fixed ratio — often borrowed from musical intervals (major third 1.25, perfect fourth 1.333, golden ratio 1.618) — to step up and down through a hierarchy with rhythmic, visually-pleasing sizing. Enter a base size (px or rem) and pick a ratio; the tool computes the nine standard slots (h1–h6, base, small, caption) and renders an "Aa" preview at each. Each row also shows the px ↔ rem equivalent (assuming a 16 px root font-size), ready to paste into a design system or Tailwind config.

Generated type scale (largest → smallest)

    Formula

    size(n) = base × ratio^n where: base = base font size ratio = scale ratio (> 1) n = step index (0 = base, +1 = h6, +2 = h5, … +6 = h1, −1 = small, −2 = caption) rem ↔ px conversion: 1 rem = root font-size px (default 16 px)

    Frequently asked

    I'm building a SaaS dashboard — which ratio should I pick?

    **Dashboards should use 1.2 (minor third) or 1.25 (major third)**. Why: (1) **High information density** — dashboards pack KPI numbers, tables, charts and nav in one screen; a big ratio (1.5, 1.618) makes the headline too dominant and steals room from useful data. (2) **Scannability** — a 1.2 scale gives eight slots (h1–h6 + body + caption) that all sit between 12 px and 32 px, so the eye can sweep the whole UI in one pass. (3) **Matches dense chrome** — sidebar items, tabs and breadcrumbs in a dashboard typically sit at 12–14 px, body at 14 px, large headings at 24 px — that's already plenty. **For comparison**: Linear, Notion and Figma all use ≤ 1.25; marketing sites like Stripe landings or Vercel use 1.333+. **Reminder**: dashboard hierarchy is driven mainly by **weight contrast (500 vs. 700)** and **colour contrast**, not by size — size is a supporting actor.

    Why is the golden ratio 1.618 used less on the web than musical ratios?

    **Because 1.618 grows too fast — nine slots span a 30× range, which doesn't fit any viewport gracefully**. Concretely: base 16 px × 1.618⁶ ≈ 286 px — a 286 px h1 dominates even a 1440 px desktop layout. Compare 1.25: 1.25⁶ ≈ 61 px — just right for a hero h1. **When does 1.618 work?** (1) **Long-form editorial / magazine** (uses 2–3 heading levels, not 6). (2) **Print design** (the A-series is actually √2 ≈ 1.414, but golden-section page grids are an editorial tradition). (3) **Logo lockups and marketing heroes** (a two-size situation, not a full ladder). **A true 9-step ladder should use 1.2–1.333**. Historically designers loved φ for romantic "found in nature" associations (sunflower spirals, nautilus shells) — but recent research (Devlin, *The Math Instinct*, 2005) shows the empirical case for "golden ratio = most beautiful" is weaker than the legend implies.

    How do I drop the generated sizes straight into Tailwind or CSS variables?

    **Three landing patterns:** (1) **CSS custom properties** (most framework-agnostic): ```css :root { --text-base: 1rem; /* 16 px */ --text-sm: 0.8rem; /* 12.8 px = base / 1.25 */ --text-lg: 1.25rem; /* 20 px */ --text-xl: 1.563rem; --text-2xl: 1.953rem; --text-3xl: 2.441rem; --text-4xl: 3.052rem; --text-5xl: 3.815rem; } ``` then `font-size: var(--text-xl)`. (2) **Tailwind `tailwind.config.ts`**: ```ts fontSize: { xs: ["0.64rem", { lineHeight: "1rem" }], sm: ["0.8rem", { lineHeight: "1.25rem" }], base: ["1rem", { lineHeight: "1.5rem" }], lg: ["1.25rem", { lineHeight: "1.75rem" }], xl: ["1.563rem", { lineHeight: "2rem" }], // … } ``` (3) **Sass / Less map**: `@each $size, $value in $type-scale { .text-#{$size} { font-size: $value; } }`. **Important**: pair each size with a sensible `line-height` — 1.1 for h1, 1.2 for h2, 1.5–1.6 for body. This tool only computes sizes; pick line-height to taste.

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    Enter two points (x₁, y₁) and (x₂, y₂); the tool instantly returns the midpoint M = ((x₁+x₂)⁄2, (y₁+y₂)⁄2), the Euclidean distance d = √((Δx)² + (Δy)²) and the slope m = Δy⁄Δx — handy for geometry homework, surveying, GIS and CAD work.

    Regular Tetrahedron Volume & Surface Area Calculator

    Enter the edge length a of a regular tetrahedron; the tool returns volume V = a³ ⁄ (6√2), total surface area A = √3·a², height h = a·√(2⁄3) and the inscribed / circumscribed sphere radii — handy for crystallography, molecular geometry (methane CH₄), organic chemistry and pure geometry problems.

    Cone Frustum (Truncated Cone) Volume & Surface Area Calculator

    Enter the larger radius R, smaller radius r and height h of a cone frustum; the tool returns volume V = πh(R² + Rr + r²) / 3, slant height ℓ, lateral surface area, the two circular faces and total surface area — useful for paper cups, lampshades, funnels and water tanks.

    Nth Root Calculator (incl. negatives & fractional roots)

    Enter the radicand x and the root index n; the tool returns the real nth root x^(1/n), handling negative x with odd n, fractional roots and complex-only cases with a clear warning — for cube roots, fifth roots, principal roots and inverse-power problems.

    Luhn Algorithm Check Digit Calculator (credit cards / IMEI / Canadian SIN)

    Enter a digit string; the tool validates it with the Luhn (mod-10 doubling) algorithm and computes the trailing check digit that makes the first N − 1 digits valid — the same scheme used by credit cards (Visa, Mastercard, Amex), phone IMEIs and Canadian SINs.

    ISBN-13 Check Digit Calculator & Validator

    Enter an ISBN-13 (with or without the trailing digit); the tool computes the correct check digit using the (1, 3) weighted mod-10 formula and validates the entire string — useful for librarians, publishers and bookshops managing catalogues.

    Digital Root Calculator

    Enter any positive integer; the tool repeatedly sums its digits until a single digit remains — showing each iteration, the numerology life-path equivalent and the mod-9 identity.

    Logistic Growth (S-curve) Calculator

    Enter carrying capacity K, initial value N₀, intrinsic growth rate r and time t; the tool applies the Verhulst logistic equation N(t) = K / (1 + ((K−N₀)/N₀)·e^(−rt)) and reports current value, instantaneous growth rate and half-saturation time — universal model for population dynamics, epidemic spread, start-up adoption curves and any growth limited by a carrying capacity.

    2×2 Matrix Inverse Calculator

    Enter a 2×2 matrix [[a, b], [c, d]]; the tool applies the closed-form A⁻¹ = 1/det(A) × [[d, −b], [−c, a]] to return the inverse together with the determinant (det = ad − bc) — and reports "singular" when det = 0.

    Midpoint of Two Points Calculator (2D / 3D)

    Enter two points (x₁, y₁) and (x₂, y₂) — with optional z to extend to 3D — and the tool applies M = ((x₁ + x₂)/2, (y₁ + y₂)/2) to give the midpoint, the Euclidean distance and the slope (in 2D). Used in high-school coordinate geometry, CAD drafting and game-coordinate math.

    Common Solids Surface Area Calculator (sphere / cube / cylinder / cone)

    Pick a solid shape (sphere, cube, cylinder, cone) and enter its dimensions; the tool returns the surface area (sphere 4πr², cube 6a², cylinder 2πr² + 2πrh, cone πr² + πrl) and the volume — useful for estimating paint, packaging, wrap film and insulation requirements.

    Six Sigma Level (DPMO) Calculator

    Enter the number of defects and total opportunities — or DPMO directly — and the tool returns the yield (1 − DPMO / 10⁶), the long-term sigma level (without shift) and the short-term Six Sigma level (with the conventional 1.5 σ shift) — the standard Motorola / Lean Six Sigma process-capability score.

    Torus Volume and Surface Area Calculator

    Enter the torus major radius R (centre of ring to centre of tube) and the tube radius r; the tool applies V = 2π²Rr² and SA = 4π²Rr to give the volume and surface area of the torus (donut shape) — useful for pipe elbows, rubber O-rings, inner tubes and magnetic ring cores.

    Cubic Equation Solver (Cardano's Formula)

    Enter the four coefficients of ax³ + bx² + cx + d = 0; the tool applies the Cardano-Tartaglia formula to return all three roots (real or conjugate-complex), the discriminant Δ and the type of root configuration.

    Weighted Average Calculator

    Enter multiple value + weight pairs; the tool returns the weighted mean Σ(xᵢwᵢ) ⁄ Σwᵢ — unlike a simple arithmetic mean, heavier-weighted entries count more. Common uses: course grades, portfolio returns, survey scores.

    Pythagorean Triple Generator (Euclid's Formula)

    Enter an upper bound N for the hypotenuse c; the tool uses Euclid's formula a = m²−n², b = 2mn, c = m²+n² to enumerate every primitive Pythagorean triple (gcd(a,b,c) = 1) up to that bound, with an option to list non-primitive multiples too.

    Cylinder Surface Area Calculator (A = 2πr(r + h))

    Enter the radius r and height h of a cylinder; the tool returns the total surface area (two circular caps + lateral surface), the lateral surface alone, and a single cap, expressed in cm², m², in² and ft².

    Annulus (Ring) Area Calculator (A = π(R² − r²))

    Enter outer radius R and inner radius r; the tool returns the annular area, the outer disk area, the inner hole area and the ring width in mm², cm², m², in² and ft² — useful for washers, gaskets, running tracks and tree-ring growth.

    Punnett Square Calculator (Monohybrid Cross)

    Enter the two parental genotypes (e.g. Aa × Aa); the tool draws the 2×2 Punnett square and reports the offspring genotype and phenotype ratios.

    Hardy-Weinberg Equilibrium Calculator

    Enter the recessive-phenotype frequency q² (or the dominant allele frequency p); the tool applies p + q = 1 and p² + 2pq + q² = 1 to back out the expected fractions of homozygous-dominant, heterozygous and homozygous-recessive genotypes, plus carrier frequency among the unaffected.

    Cricket Required Run Rate (RRR) Calculator

    Enter the target score, current score, overs bowled and total overs; the tool returns the required run rate (RRR), current run rate (CRR), balls remaining and runs-per-ball needed — useful for cricket fans tracking a chase.

    Earned Run Average (ERA) Calculator

    Enter the pitcher's earned runs (ER) and innings pitched (IP); the tool applies ERA = (ER × 9) / IP to give the normalised "earned runs per nine innings" — the universal pitching benchmark used by MLB, NPB, KBO, CPBL and the WBSC.

    Ten-Pin Bowling Score Calculator

    Enter the pin counts for all ten frames; the tool applies World Bowling / USBC rules for strike (X) and spare (/) bonuses, including the tenth-frame fill balls, and gives the running per-frame total and final score.

    NFL Passer Rating Calculator

    Enter pass attempts (ATT), completions (CMP), passing yards (YDS), touchdowns (TD) and interceptions (INT); the tool applies the four-component formula the NFL has used since 1973 to give the 0–158.3 passer rating, the tier (perfect 158.3 down to poor) and the four sub-scores.

    OEE — Overall Equipment Effectiveness Calculator

    Enter planned production time, actual run time, ideal cycle time and total / good unit counts; the tool computes OEE = Availability × Performance × Quality — the universal manufacturing KPI (world-class ≥ 85 %) used in lean management and TPM — and breaks out each of the three component factors.

    Bowling Handicap Calculator

    Enter the bowler's average, the league's base score (commonly 200 or 220) and the handicap percentage (typically 80 %, 90 % or 100 %); the tool applies handicap = max(0, ⌊(base − average) × percent / 100⌋) for the per-game handicap — the standard USBC, World Bowling and league formula — plus the multi-game handicap series total.

    Golf Handicap Index Calculator (World Handicap System)

    Enter up to 20 recent scores plus the course's Course Rating and Slope Rating; the tool applies the World Handicap System (WHS, USGA / R&A 2020) Rule 5 — average the best N of the last 20 score differentials — to give the official Handicap Index.

    Two's Complement Calculator

    Enter a decimal value and a bit width (8 / 16 / 32 / 64 bit); the tool returns the two's-complement binary and hexadecimal representation plus the representable range — essential for computer-science students and embedded developers.