AP Biology Formula Sheet 2027: Free One-Page Printable PDF

TLDR

• Covers all essential AP Biology equations: water potential, Hardy-Weinberg, chi-square, Gibbs free energy, population growth, and more.

• Organized unit by unit with variable definitions for clarity.

• Designed as a one-page printable PDF for fast reference.

• Includes constants, statistical formulas, and tutor tips for exam day.
  
  

  👉 Download the Free AP Biology Formula Sheet (PDF) above

Introduction

The College Board gives you an official, two-sided Equations and Formulas sheet on exam day, so you do not need to memorize every AP Biology equation. You do need to know which formula fits each question, and that takes practice with the sheet before the exam on May 3, 2027.

This free one-page AP Biology formula sheet gathers the equations you will use most, organized by unit below. Download the PDF above with no signup, print it, and keep it next to you every time you work a practice problem.

AP Biology Formulas by Unit

Unit 1: Chemistry of Life

• Water Potential: Ψ = Ψs + Ψp

• Solute Potential: Ψs = -iCRT

• Surface Area to Volume Ratio: SA:V = Surface Area / Volume

Unit 2: Cell Structure and Function

• Surface Area to Volume Ratio (applied to transport efficiency)

• Rate of Diffusion: Rate = Distance / Time

Unit 3: Cellular Energetics

• Gibbs Free Energy: ΔG = ΔH – TΔS

• ATP Yield: ~36–38 ATP (aerobic), ~2 ATP (anaerobic)

• Enzyme Reaction Rate: Rate = ΔProduct / Δt

Unit 4: Cell Communication and Cell Cycle

Note: No unique equations introduced in this unit.

Unit 5: Heredity

• Probability Rules:

  • Multiplication Rule: P(A and B) = P(A) × P(B)

  • Addition Rule: P(A or B) = P(A) + P(B) – P(A and B)

• Chi-Square: χ² = Σ (O – E)² / E

• Degrees of Freedom: df = categories – 1

  For the genetics concepts behind these equations, see our AP Biology Unit 5 heredity cheat sheet.

Unit 6: Gene Expression and Regulation

Note: No unique equations introduced in this unit.

Unit 7: Natural Selection

• Hardy–Weinberg: p + q = 1 and p² + 2pq + q² = 1

• Relative Fitness: w = (offspring of genotype) / (offspring of most successful genotype)

  For the evolution concepts behind Hardy-Weinberg, see our Unit 7 natural selection cheat sheet.

Unit 8: Ecology

• Exponential Growth: Nt = N0 * e^(rt)

• Logistic Growth: dN/dt = rN (1 – N/K)

• Mark–Recapture: N = (M × C) / R

• Photosynthesis / Respiration Rate: Rate = ΔO2 / Δt or ΔCO2 / Δt

• Net Productivity: NPP = GPP – R

  For the ecology concepts behind these growth models, see our Unit 8 ecology cheat sheet.

Statistics and Data Analysis

• Standard Error: SE = s / √n

• Confidence Interval (95%): x̄ ± (1.96 × SE)

Why This Formula Sheet Matters

Formulas are a smaller part of AP Biology compared to free-response questions, but they’re also some of the easiest points to secure. The key is not just memorizing them, but knowing when to apply them.

Tutor Tip: Our Johns Hopkins tutor says, always highlight what the question is asking. Then pick the formula that matches, this saves time and prevents small mistakes.

Losing points on free-response questions or data analysis? Meet our AP Biology tutors and book a free consultation to get matched.

📌 Book a free AP Biology strategy session today