Solve proportions (A:B = C:D), find missing terms through cross-multiplication, and enlarge or shrink ratios with scale factors and greatest common divisor (GCD) simplification.
• Module 1 (Proportion): Enter any 3 of the 4 values (A, B, C, D) to solve for the missing term via cross-multiplication (A × D = B × C).
• Module 2 (Ratio Scaling): Enter ratio terms, choose Shrink or Enlarge, and provide a scale factor.
Please provide any three values below to calculate the fourth in the ratio A:B = C:D.
Provide any 3 values on the left (A, B, C, or D) to solve the 4th with step-by-step cross-multiplication.
Understanding proportional relationships, cross-multiplication, aspect ratio math, and GCD simplification.
A ratio is a mathematical comparison of two or more quantities indicating how many times one value is contained within another. In a ratio A : B, the first number A is the antecedent and the second number B is the consequent.
Ratios can be written in three common notations:
A proportion is an equation stating that two ratios are equal:
Standard for YouTube, HDTV, Full HD (1920×1080), 4K UHD (3840×2160).
Standard television broadcast, iPad displays, and vintage PC monitors (1024×768).
Cinematic anamorphic format and gaming monitors (3440×1440).
A ratio compares two quantities (e.g., 3:4). A proportion is a statement that two ratios are equal to each other (e.g., 3:4 = 6:8).
Find the greatest common divisor (GCD) of both terms and divide both numbers by the GCD. For example, for 250:280, the GCD is 10, giving 25:28.
Yes. Decimal ratios (like 1.5 : 2.5) can be converted to integer ratios by multiplying both terms by 10 or 100 and simplifying (1.5 : 2.5 → 15 : 25 → 3 : 5).
Because A/B = C/D, multiplying both sides by (B × D) yields A × D = B × C. Dividing both sides by the known coefficient yields the exact value of the unknown variable.