What is a ratio?

A ratio compares two quantities to show how many times one value contains the other, commonly written as a:b, a to b, or a/b. It’s meaningful only when comparing like units, and it can extend to more than two terms for multi‑part comparisons such as ingredient mixes or budget splits.

How to write and simplify ratios

• Express the comparison: boys:girls = 12:15 can be reduced to 4:5 by dividing both terms by their greatest common divisor.

• Keep order consistent: a:b is not the same as b:a; swapping terms changes the meaning.

• Multiple‑term ratios scale the same way: 1:2:3 scaled by 5 becomes 5:10:15 for five identical batches.

Ratios in everyday life

• Cooking and baking: Scale ingredient ratios up or down to change serving size without altering taste.

• Maps and models: A 1:50,000 map means 1 unit on paper equals 50,000 units in reality.

• Finance and odds: Compare parts to whole for allocations, and part to part for mix proportions.

• Screens and media: Aspect ratios define the shape of displays and video frames.

Aspect ratios and common resolutions

Aspect ratio compares width to height; many displays standardize around 4:3, 16:10, and 16:9. Here are typical pairs your Ratio Calculator can recognize and convert between:

• 480p: 3:2 at 720×480

• 576p: 5:4 at 720×576

• 720p: 16:9 at 1280×720

• 1080p (FHD): 16:9 at 1920×1080

• 2160p (4K UHD): 16:9 at 3840×2160

• 4320p (8K UHD): 16:9 at 7680×4320

• 8640p: 16:9 at 15360×8640

• SVGA: 4:3 at 800×600

• WSVGA: ~17:10 at 1024×600

• XGA: 4:3 at 1024×768

• XGA+: 4:3 at 1152×864

• WXGA: 16:9 at 1280×720

• WXGA: 5:3 at 1280×768

• WXGA: 16:10 at 1280×800

• SXGA (UVGA): 4:3 at 1280×960

• SXGA: 5:4 at 1280×1024

• HD: ~16:9 at 1360×768

• HD: ~16:9 at 1366×768

• SXGA+: 4:3 at 1400×1050

• WXGA+: 16:10 at 1440×900

• HD+: 16:9 at 1600×900

• UXGA: 4:3 at 1600×1200

• WSXGA+: 16:10 at 1680×1050

• WUXGA: 16:10 at 1920×1200

• QWXGA: 16:9 at 2048×1152

• WQHD: 16:9 at 2560×1440

• WQXGA: 16:10 at 2560×1600

Tip: When converting between resolutions and aspect ratios, maintain the width:height proportion; if one dimension changes, scale the other to keep the ratio constant.

Working with multi‑term ratios

For a recipe using a 1:2:3 ratio of butter:sugar:flour, multiply each term by the same factor to reach your target batch size. If one cake uses 1:2:3 and you need five cakes, scale to 5:10:15, then apply actual units (e.g., cups or grams) to each term.

Ratios vs. proportions

• Ratio: a single comparison (e.g., 4:5).

• Proportion: a statement that two ratios are equal (e.g., 4:5 = 8:10). In proportions, cross products are equal, so a:b = c:d implies a×d = b×c, a property the Ratio Calculator uses to solve for unknowns.

How a Ratio Calculator helps

• Simplify ratios to lowest terms.

• Scale multi‑part ratios for recipes, mixes, or budgets.

• Convert between aspect ratios and pixel dimensions.

• Solve proportions by finding missing terms with cross‑multiplication.

• Validate inputs and preserve order, so results match your intent.

Practical tips for accurate results

• Always align units first; convert to the same unit before forming a ratio.

• Reduce ratios for clarity; lowest‑term ratios are easier to compare.

• Preserve ordering across steps; changing term order changes meaning.

• For screens, divide width by height to confirm the underlying ratio before resizing.