Calculation Methodology

The single canonical formula. All percentage tools on the site reduce to this expression after subject-level aggregation. For multi-subject boards (CBSE, ICSE, state boards) we sum "Obtained" across subjects and divide by the sum of "Total" before multiplying by 100.

Reference: NCERT Class IX Mathematics, Chapter 8 (Comparing Quantities). Aligned with CBSE Examination Bye-Laws § 40 on percentage computation.

The 9.5 multiplier is the official conversion CBSE uses to map its 10-point Cumulative Grade Point Average to a percentage. It originates from averaging the grade-mid-point bands across the A1–E2 scale.

CBSE Circular Acad-XX/2011 on CGPA computation. See also our deep-dive blog post.

US-style 4.0 GPA is a normalised scale where 4.0 = A. Direct proportional mapping is the most common approach used by US universities for credential evaluation, though some use WES-style band conversions instead.

World Education Services (WES) iGPA methodology, 2024 revision.

IGNOU uses a 70/30 split between term-end theory exam (70%) and continuous assessment / assignment marks (30%) for most undergraduate and postgraduate programmes. Result cards show the weighted aggregate.

IGNOU Common Prospectus 2024, Chapter on Evaluation and Award.

For CBSE Class 10 students who took 6 subjects, the official percentage is computed using the top 5 scores, with one constraint: at least one language (subject group 1: English / Hindi / regional) must be included. If a skill subject (IT 402, AI 417, etc.) scores higher than a main subject, it can replace the lowest-scoring main subject in the top 5.

CBSE Circular Acad-22/2021 on Skill Subject Replacement. See our explainer.

Every linear unit conversion on our converter pages uses the formula:

Conversion factors are defined relative to each category's canonical SI base unit (meter for length, kilogram for mass, joule for energy, etc.). All multipliers in the codebase are exact rational definitions where available — for example, 1 inch is defined as exactly 0.0254 metres, not a decimal approximation. View the full table in src/data/unit-converters.ts.

BIPM (Bureau International des Poids et Mesures) SI Brochure, 9th edition (2019); NIST Special Publication 811 (2008 ed.).

Temperature is non-linear because each scale has a different zero point. Our converter uses the exact offset formulas above rather than approximating with a linear factor.

Our currency converter sources daily ECB (European Central Bank) reference rates via the open-source Frankfurter API — no API key, MIT licensed. Rates refresh once per ECB business day (around 16:00 CET). Our backend caches them for 6 hours via Vercel's CDN.

These are indicative mid-market rates. Banks and credit-card networks typically charge a 1–3% spread above the mid-market rate. For time-sensitive transactions check with your bank.

European Central Bank Foreign Exchange Reference Rates (daily). Hawkers (Frankfurter, OpenExchangeRates, etc.) republish these — we use Frankfurter because it is fully open source and rate-limit-free.

Our board result redirector is a privacy-first deep-link helper. We do not fetch, parse, or display result data from any board. We never store, log, or transmit roll numbers. The form uses window.open() to send the user to the official board portal. From that point on, the interaction is between the user and the board — we are not a party to it.

Each portal URL in the directory is sourced from the board's own published press releases and website. We re-verify URLs annually before the result season and flag any whose result page is gated behind a homepage navigation step.

Every calculation on this site runs entirely in your browser. We do not send marks, GPA values, roll numbers, or converter inputs to our servers. The only server requests are for static content (HTML, CSS, JS, images) and the cached currency-rate proxy at /api/rates (which never sees your conversion amount).

See our Privacy Policy for the formal data-handling statement.