# Effort Estimation

> Estimate engineering effort with agile techniques — story points, t-shirt sizing, three-point estimation, capacity planning.

- Skill: `swestash/effort-estimation` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add swestash/effort-estimation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/swestash/effort-estimation/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: SWEStash (https://skillmd.com/u/swestash)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/swestash/effort-estimation

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# Effort Estimation

Produce honest, useful estimates without false precision. Estimates are forecasts,
not commitments — always ranges, always improving as you learn more.

## Workflow

### Step 1: Ensure Tasks Are Defined

You can't estimate undefined work. Tasks must be broken down (use `feature-planning`
if not), have acceptance criteria, and have at least a sketched technical approach.
"I can't estimate this until we do a spike" is a valid and responsible answer.

### Step 2: Choose the Method

T-shirt sizing for roadmap and early-stage sizing; story points (Fibonacci) for
sprint planning and velocity tracking; three-point estimation for budget requests
and high-uncertainty, high-stakes work; time-based only for well-understood tasks.
See [references/estimation-methods.md](references/estimation-methods.md) for
detailed guidance on each method.

### Step 3: Apply It

Estimate per task, not the project as a single unit; relative to known work rather
than in absolute terms; as a team where possible (the familiarity gap between
estimators reveals hidden complexity); with uncertainty explicit. Re-estimate when
spikes complete or requirements clarify.

### Step 4: Translate for Stakeholders

Convert to time or cost via team velocity or loaded cost, add a 20-30% buffer for
unknowns, and communicate a range in stakeholder language — weeks and dollars, not
story points. A single number becomes a commitment; a range communicates confidence.

### Step 5: Track and Calibrate

Compare estimated vs actual each sprint, look for systematic bias, and recalibrate
velocity on the last 3-5 sprints, not the all-time average.

## Principles Applied

- **KISS**: Use the simplest estimation method appropriate. T-shirt sizing is fine for most roadmap decisions.
- **Honesty over optimism**: A realistic estimate that disappoints a stakeholder is better than an optimistic estimate that misses a deadline.
- **YAGNI**: Don't estimate items far in the future with precision. Estimate near-term work in detail, far-term work in ranges.