Free Online Color Contrast Analyzer | WCAG AA/AAA Contrast Ratio

Free Online Color Contrast Analyzer

Free online color contrast analyzer is the fastest way to confirm whether a foreground and background color pairing stays readable for real users across screens and lighting. This tool lets you choose both colors and instantly calculates the contrast ratio and WCAG compliance ratings (AA/AAA), which helps catch accessibility issues before design handoff. WCAG contrast checks matter because small text, thin fonts, and subtle color palettes can fail even when they “look fine” on one monitor. For reference, common targets are 4.5:1 for normal text (AA) and 7:1 for normal text (AAA), with lower requirements for large text. The contrast ratio itself is based on relative luminance, using the WCAG definition — 
(L1 + 0.05) / (L2 + 0.05) — where L1 is the lighter luminance and L2 the darker. Use the checker early in UI work: validate buttons, links, form labels, and disabled states, not just hero headings. WizardOfAZ keeps the workflow simple so designers and developers can verify pairs quickly without installing software. A practical habit is to test the same colors in both light mode and dark mode, because the pair that passes in one theme can fail in the other.

Contrast To Light Green

Contrast to light green is often harder than expected because many light greens sit close to white in luminance, causing washed-out text and low perceived separation. Start by deciding what light green is used for—background fill, accent border, or text—because the same hex value can be safe in one role and risky in another. When light green is the background, darker neutrals (near-black, charcoal) frequently deliver a stronger ratio than mid-gray, especially for body text. This tool helps by letting the exact foreground and background be picked and then returning both the contrast ratio and AA/AAA pass/fail. If the goal is a softer look, try increasing font weight or size only after confirming ratio, since WCAG thresholds differ by text size. For UI elements (icons, input outlines), remember non-text contrast targets are commonly 3:1, so borders may need to be darker than the background tint. A reliable workflow is to test three candidates (dark neutral, deep green, deep blue) and keep the one that passes while matching the brand palette. This keeps the design consistent without sacrificing legibility for users with low vision or glare.

Color Contrast For Purple

Color contrast for purple depends heavily on whether purple is used as the text color or as a background, because different purples span a wide luminance range. Deep purples can pass easily on white backgrounds, but lighter lavender tones often fail for normal-sized text unless paired with very dark text. A quick way to de-risk the choice is to check the pair in this contrast tool, then adjust only one variable at a time (darken purple, brighten background, or change text to near-black). When purple is the background, white text can look crisp but still fail if the purple is too light, so relying on “looks bright” is not enough. If the design uses purple for links, test visited and hover states as separate colors, since small shifts can change compliance. For accessibility documentation, saving the exact hex pair and its ratio helps developers implement the correct tokens later. Because contrast ratio is based on relative luminance, two colors that feel different in hue can still end up too close in luminance and fail. Checking early avoids last-minute rework when QA or audits flag contrast issues.

Color Contrast For Green

Color contrast for green is tricky because greens can appear bright to the eye while still producing poor contrast against white or light gray backgrounds. The safest approach is to test the exact green used in the UI, not a named color assumption, since two “brand greens” can behave very differently. If green is used for success messages, confirm that the text color meets at least AA for normal text; success messaging is often small and easily missed when contrast is low. For green buttons, test both label text and focus outline, because accessibility includes interaction states, not only static screens. Useful experiments include: darkening the green by a small step, switching label text to near-black, or using a lighter green background with dark text instead of the reverse. - Test green text on white. - Test white text on green. - Test green border against white. Each variation can pass or fail independently, and this tool gives the ratio and AA/AAA rating immediately. The result is a green palette that communicates meaning without excluding users who struggle with low contrast.

What Colors Contrast Black

What colors contrast black best depends on the use case: readable text, attention-grabbing callouts, or subtle UI separation. For readability on black backgrounds, very light colors (white and near-white tints) usually provide the strongest contrast ratios, but some saturated yellows and cyans can also perform well if their luminance is high enough. This tool helps confirm the exact ratio rather than relying on intuition, because certain bright hues can still underperform if they are not sufficiently light in luminance. For body text, aim for WCAG AA (commonly 4.5:1 for normal text) as a baseline, then push toward AAA when the design is text-heavy. If the intent is to keep a softer aesthetic than pure white-on-black, test off-whites and light grays until the ratio stays compliant. For UI borders on black, the “3:1 for components” guidance is a useful checkpoint, since low-contrast outlines disappear quickly on OLED screens. Testing multiple candidates side by side (white, warm white, cool gray) often reveals that minor tint changes can preserve style while keeping accessibility. The practical outcome is fewer readability complaints in dark mode and more consistent legibility across devices.

Best Color Contrast With Red

Best color contrast with red usually means choosing a foreground/background pairing that keeps warning or error messaging readable without vibrating, blurring, or bleeding on screens. Red used as text on white can fail if the red is too light, so the safest pattern is often dark red text on a very light background or white text on a deep red background. Before deciding, run the exact hex values in the contrast checker to verify AA/AAA results rather than assuming “primary red” is acceptable for small font sizes. For forms, also test red error text next to neutral labels—contrast needs to work for both the message and any accompanying icons or outlines. If the brand palette uses bright red, consider reserving it for icons/badges and using a darker shade for text so paragraphs remain compliant. A small adjustment toward deeper red often improves contrast dramatically while still reading as the same brand color. This tool makes those incremental tweaks easy to evaluate because it shows the ratio immediately after switching colors. The result is error styling that stays visible for users in bright light, low-quality displays, or with reduced contrast sensitivity.

Best Color Contrast With Black

Best color contrast with black is often achieved with very light foreground colors, but the best choice also depends on glare, eye strain, and brand tone. Pure white on pure black creates maximum separation, yet some interfaces prefer slightly softened whites to reduce harshness while still meeting AA/AAA. Using this tool, test a few near-white options (for example, warm off-white vs cool off-white) to keep the ratio high while matching the UI mood. For accent colors on black (links, highlights), verify the ratio for each state—normal, hover, active—because small color shifts can drop below thresholds. If black is used for text on colored backgrounds, the check works the same way: pick the background and confirm that black text meets the target ratio for the font size. Remember that contrast ratio is luminance-based, so a bright-looking color is not guaranteed to be sufficiently light against black without testing. A consistent workflow is to lock typography first (size/weight), then choose colors that meet requirements for that typography, not the other way around. That approach keeps dark themes readable without constant redesign loops later.

Best Color Contrast With Green

Best color contrast with green depends on whether green is the emphasis color or the canvas color, because those roles demand different contrast strategies. When green is the background (buttons, banners), white text can work well only if the green is deep enough; lighter greens typically need dark text to pass. When green is the text color (links, status labels), it often needs to be darker than expected to meet AA on white. The fastest way to choose is to test a small set of candidate greens against the intended background using this tool and keep the first one that passes with comfortable margin. For brand consistency, keep one “text green” token and one “background green” token rather than reusing the same hex for both roles. Also test focus rings and outlines; green outlines on white are a frequent failure point because they are thin and low-contrast. If the design includes charts, test green lines against the chart background too, since thin strokes need stronger contrast to remain visible. This yields a green system that reads clearly in both UI controls and longer-form content.

Best Color Contrast With White

Best color contrast with white is not automatically “use black everywhere”; it is about picking text and UI colors that remain readable while supporting hierarchy and brand tone. White backgrounds can hide light grays, pastels, and thin colored text, so testing prevents subtle failures that only show up on low-quality monitors or in bright rooms. The contrast checker is useful here because it reports AA/AAA directly once a foreground and background are chosen. If the interface uses white cards on slightly off-white pages, confirm those boundaries too; non-text contrast needs to be sufficient for component edges and separators. For links on white, saturated blues often pass, but some modern muted palettes require darker shades to avoid falling below 4.5:1 for normal text. If the UI uses very large headings, remember large text has different thresholds, but body text and captions still need stricter contrast. A strong practice is to test the smallest text size in the design system first and only approve colors that work at that size. This keeps white-based layouts clean while still meeting accessibility expectations.