---
type: BaZi Concept
title: "Decade Luck & Day-Master Strength (大運與強弱)"
description: "How the ten-year luck pillars are started and run, and how this tool scores Day-Master strength — with the method stated."
resource: https://localpapa.com/tools/bazi.html
category: "BaZi · Luck"
tags: [bazi, four-pillars, dayun, luck-pillars, strength]
timestamp: 2026-06-21T00:00:00Z
---

# Decade Luck & Strength · 大運與日主強弱

The decades run from the **Month pillar**, ten years each. Direction: **men born in a yang year and women born in a yin year go forward**, the other two backward — the same convention as Zi Wei and the Palm Sutra. The starting age counts the days from birth to the **next major term** going forward, or from the **previous** one going backward, at **three days to the year**. Those terms are exactly the lines at which the month branch changes, and this tool uses that same boundary for both — so the decades and the Month pillar can never disagree.

## Day-Master strength

How strength is scored (schools weight this differently, so the method is stated): the eight characters — four stems and the hidden stems of four branches — are split into **support** (same element as the Day Master, plus what generates it) and **drain** (what controls it, what it generates, what it controls). The month branch commands the season and counts double; a branch’s main hidden stem counts 1 and the others 0.5. The difference over the total gives a ratio from −1 to +1, banded at ±0.15. **This is a transparent measure, not a verdict** — choosing a useful god also involves climate (hot/cold, dry/damp), bridging elements and whether the structure holds, none of which a weight table settles. This tool gives the indicator and stops there.

### The three bands

- **strong** — The Day Master runs strong: more support than drain. Stamina and conviction are there and pressure is bearable; such charts usually want an outlet rather than more reinforcement.
- **balanced** — The Day Master is balanced: support and drain are close. A flexible structure with room to manoeuvre; what it needs shifts with the decades and years rather than being fixed.
- **weak** — The Day Master runs weak: more drain than support. Energy depletes and sustained pressure tells; such charts usually want reinforcement — mentors, learning, allies — over brute effort.

## Hidden stems 藏干

A branch is not a single element. Each hides one to three stems — a main one plus secondary ones — and **the Ten Gods really come from these hidden stems**. Reading only the four visible stems leaves just three to work with (the Day stem is the self); the hidden stems let every branch say whether it is wealth, authority or resource to the Day Master.

> Choosing a *useful god* (用神) is deliberately **not** offered here. It depends on climate, bridging elements and whether the structure holds — judgement a weight table cannot stand in for. The tool gives a transparent indicator and stops.

Cast a chart and step through the decades at <https://localpapa.com/tools/bazi.html>.

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*[Annual fortune](./annual.md) · [The Ten Gods](./tengods/index.md) · [Day masters](./daymasters/index.md) · [BaZi knowledge base](./index.md)*