Work it out.
Calculators
px ↔ rem conversion
CSS (web)
Colour contrast (WCAG)
WCAG 2.1, succeskriterium 1.4.3 og 1.4.6 (W3C)
Screen pixel density (PPI)
Geometri (Pythagoras' læresætning)
Page download time and LCP assessment
Netværks-grundformel + Core Web Vitals-tærskler (web.dev/Google)
CLS — calculate the score of one layout shift
web.dev — Cumulative Layout Shift (CLS), Core Web Vitals (Google)
CSS Grid — number of columns (auto-fill/minmax)
Geometri / CSS Grid Layout-teknik (auto-fill + minmax, W3C-specifikation)
SLA uptime → permitted downtime
Standard SLA-nedetidsberegning (branchepraksis brugt af bl.a. AWS/Azure/Google Cloud SLA'er)
Password entropy and brute-force time
Informationsteori (Shannon-entropi) + NIST SP 800-63B-vejledning om digital identitet
API rate limit — how long will my calls take?
GitHub REST API-dokumentation (rate limits)
Hosting traffic and data requirements per month
Forholdsregning — sidevægt jf. HTTP Archive (median sidevægt-statistik)
Freelance hourly rate and project price
Ren omkostningsdækning på dine egne tal + dansk momssats (Skattestyrelsen, 25%)
Responsive image — required file width (srcset)
web.dev/MDN — responsive billeder (srcset/sizes-teknik)
WCAG — is the clickable target large enough?
WCAG 2.2, succeskriterium 2.5.8 Target Size (Minimum), AA (W3C) + 2.5.5 Target Size (Enhanced), AAA
SEO — title and meta description: is it too long?
SEO-branchedata — pixelbredde-analyser af Google SERP (Moz/Search Engine Land-typiske grænser, 2026)
Fluid font size with clamp()
CSS Values 4 · clamp() and vw unit (W3C/MDN) · method from Utopia.fyi
Typographic scale (modular scale)
Modular scale · Tim Brown, «More Meaningful Typography» (A List Apart 2011)
Image aspect ratio and reserved height
web.dev 'Optimise CLS' + MDN aspect-ratio (CSS Box Sizing 4)
Tools that work in all subjects
Whatever your programme is called, these tools calculate the same — Pythagoras, area, percentages and units are not tied to one trade.
- Pythagorasa² + b² = c²Find the missing side, set out a right angle, check whether a room is square, and find the space diagonal.
- Area and perimeterm²Rectangle, triangle, trapezium, circle and composite shapes — area and perimeter.
- Volume and surface aream³ · lBox, cylinder, cone, sphere, pyramid, prism, pipe and frustum — also in litres.
- Percent%Percentage of, how many per cent, percentage change, discount and VAT.
- Scale and ratios1 : 50From drawing to reality, area and volume to scale, the rule of three and dividing in a ratio.
- Unit convertermm ↔ mFrom mm to km, Pa to bar and kB to GB — with the unit staircase.
- Time calculations and the clockt : minTime between two clock times, add time, and 1.75 h = 1 h 45 min for the timesheet.
- Slope and fall% · ° · 1:xFall from level to level, in per cent, per mille, degrees and mm per metre — and the height difference.
- Material consumption including wastem² + %Boards, paint, battens at c/c spacing and packs — for a composite surface or a whole room, with waste.