The Most Effective Decluttering Rules Explained (20/20/20, 3-3-3 & More)

Q: What is the 3-3-3 rule for decluttering?

The 3-3-3 rule, officially called Project 333, is a minimalist wardrobe challenge created by Courtney Carver. You choose 33 clothing items — including shoes, outerwear, and accessories but excluding underwear and workout gear — and wear only those for 3 months, boxing up the rest. After 3 months you reassess, and items you didn't miss can be donated.

Q: What are the 4 Cs of decluttering?

The 4 Cs of decluttering are a four-phase process framework: Clear Out (remove everything from the space), Categorize (group like items together to reveal duplicates), Cut Out (decide what to keep, donate, or discard, working category by category), and Contain (find appropriate storage for what remains only after the previous steps are complete).

Q: Which decluttering rule is most effective?

The most effective decluttering rule depends on your situation. The 20/20/20 rule works best for just-in-case items; the 3-3-3 rule is ideal for wardrobe clutter; the 4 Cs provide a structured process for whole-room decluttering; and the 90/90 rule is best for stubborn 'maybe' items. Many people combine them, using the 4 Cs as a process and the 20/20/20 or 90/90 rule as decision tie-breakers.

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By Clara Bennett · Updated May 2026 · 8 min read

Knowing what to get rid of is one of the hardest parts of decluttering. That's exactly why professional organizers and minimalist thinkers have developed clear, memorable rules to remove the guesswork. Whether you're paralysed by "but what if I need it someday?" or drowning in a wardrobe you never wear, there's a framework here for you.

Below, we break down the four most effective decluttering rules — the 20/20/20 Rule, the 3-3-3 Rule (Project 333), the 4 Cs, and the 90/90 Rule — so you can pick the one that fits your situation and start clearing with confidence.

Rule 1 Best for: "Just-in-case" clutter

What Is the 20/20/20 Rule for Decluttering?

The 20/20/20 Rule

If you can replace an item for under $20 and find a replacement in under 20 minutes, let it go — no matter how useful you imagine it might one day be.

Coined by minimalism advocates Joshua Fields Millburn and Ryan Nicodemus (The Minimalists), the 20/20/20 rule is designed to dismantle one of the most stubborn mental traps in decluttering: the "just-in-case" mindset. We hold onto items not because we use them, but because we're afraid of needing them later.

The rule reframes the calculation. Yes, getting rid of that spare extension lead might mean buying a new one someday — but if it costs less than $20 and you can grab one from a nearby store in under 20 minutes, the cost of keeping it (space, mental load, clutter) almost certainly outweighs the cost of occasional replacement.

How to Apply the 20/20/20 Rule

1 Pick up the item and ask: "Am I keeping this just in case I need it someday?" If yes, proceed.
2 Could you replace it for under $20? Check Amazon or a local store in your head.
3 Could you find a replacement within 20 minutes — online order, nearby shop, or borrow from a neighbour?
4 If both answers are yes — let it go. The regret risk is genuinely low.

💡 Perfect for: spare cables, extra tools, duplicate kitchen gadgets, backup office supplies, "spare" anything you haven't touched in months.

Rule 2 Best for: Wardrobe overwhelm

What Is the 3-3-3 Rule (Project 333) for Decluttering?

The 3-3-3 Rule — Project 333

Dress with 33 items or fewer for 3 months, boxing up everything else. After 3 months, reassess. Repeat each season.

Created by minimalist coach Courtney Carver, Project 333 is a wardrobe decluttering challenge that proves you need far less clothing than you think. The numbers are elegantly simple: 33 items, 3 months, one box for the rest.

The genius is in the experiment. You don't donate everything immediately — you box it up. This removes the fear of regret, letting you test a capsule wardrobe without permanence. After 3 months, most people find they barely touched the boxed items and feel liberated by the simplicity of getting dressed each morning.

What Counts Toward Your 33 Items?

✅ Counts toward 33

•Tops, shirts, blouses
•Bottoms (trousers, skirts, shorts)
•Dresses & jumpsuits
•Outerwear (coats, jackets)
•Shoes & boots
•Accessories (bags, scarves, jewellery)

❌ Excluded (doesn't count)

•Underwear & socks
•Workout / athletic gear
•Pyjamas & loungewear
•Clothes only worn for work uniforms
•Items in the "box" (stored away)

How to Start Project 333

1 Empty your entire wardrobe onto the bed. Every item, no exceptions.
2 Choose your 33 favourites — items you genuinely love, that fit well right now, and work for your current life season.
3 Box up the rest. Label it with today's date. Store it out of sight.
4 Live with your 33 items for 3 months. Take note of what you actually wear vs. what you skip.
5 At 3 months, open the box. Anything you didn't miss can be donated with zero guilt.

💡 Perfect for: people who feel they have "nothing to wear" despite a full wardrobe, chronic over-shoppers, and anyone wanting to build a cohesive capsule wardrobe.

Rule 3 Best for: Full-home decluttering

What Are the 4 Cs of Decluttering?

The 4 Cs of Decluttering

A four-phase framework for any space: Clear Out → Categorize → Cut Out → Contain. Follow the steps in order for a thorough, lasting result.

Unlike the other rules on this list, the 4 Cs aren't a decision-making tool — they're a process. Think of it as a complete operating system for tackling any room, drawer, or cupboard from start to finish. Each C builds on the last.

1. Clear Out

Remove everything from the space — every drawer, shelf, and cabinet. Work with a blank canvas. This step alone reveals just how much you've been storing out of habit rather than intention. Don't skip it; you cannot properly assess what you have while it's still packed in.

2. Categorize

Group like with like. All books together, all batteries together, all cables together. Categorizing shows you duplicates you didn't know you had (seven pairs of scissors? really?) and makes the next step — cutting — significantly easier because the volume of each category is visible at a glance.

3. Cut Out

Now decide what to keep, donate, or discard — working category by category, not item by item. When you see all 12 coffee mugs lined up together, it's far easier to choose your 4 favourites than when you're pulling them out one at a time. This is where the other rules (20/20/20, 90/90) work brilliantly as tie-breakers.

4. Contain

Only after steps 1–3 are done should you think about storage solutions. Buying organising products before cutting is one of the most common decluttering mistakes — you end up neatly organising things you should have donated. Now that you know exactly what you're keeping, choose containers, baskets, or drawer dividers that fit what remains.

💡 Perfect for: whole-room decluttering sessions, anyone who gets overwhelmed by where to begin, and people who've tried decluttering before but couldn't make it stick.

Rule 4 Best for: "Maybe" item paralysis

What Is the 90/90 Rule for Decluttering?

The 90/90 Rule

Ask two questions: Have you used this item in the last 90 days? And will you realistically use it in the next 90 days? If the answer to both is no — let it go.

Also from The Minimalists, the 90/90 rule is a usage-based test that cuts through emotional attachment and replaces it with honest data about your actual life. Most of us wildly overestimate how often we'll use something we're holding onto "just in case."

Three months (90 days) is long enough to be meaningful but short enough to be honest. You can picture your life over the last 3 months fairly clearly — and you can make a reasonable prediction about the next 3. This eliminates the vague fantasy of "one day I might need this" that keeps drawers stuffed and shelves overloaded.

Applying the 90/90 Rule: Quick Examples

Item	Used in last 90 days?	Will use in next 90 days?	Verdict
Bread maker	No	Probably not	Donate
Winter coat	No (it's summer)	Yes — in 6 weeks	Keep
Fondue set	No	No	Donate
Camera lens (hobbyist)	No	Yes — booked a trip	Keep
Exercise bike	No	Honestly, no	Donate

💡 Perfect for: "maybe" piles, hobby equipment, kitchen gadgets, seasonal items you're not sure whether to keep, and any item you've been staring at for months without deciding.

Which Decluttering Rule Should You Use?

You don't have to pick just one — these rules are designed to complement each other. Here's a quick guide:

👕

Wardrobe overwhelm? Start with the 3-3-3 Rule. It's the fastest way to feel in control of your closet without making permanent decisions.

🤔

Stuck on "but what if I need it?" Use the 20/20/20 Rule. It's the fastest mental reset for just-in-case paralysis.

🏠

Tackling a whole room? Follow the 4 Cs framework as your process, then use 20/20/20 or 90/90 as tie-breakers during the "Cut Out" phase.

📦

Staring at a "maybe" pile? Apply the 90/90 Rule item by item. It's the most honest test of whether something earns its space.

Frequently Asked Questions

What is the 20/20/20 rule for decluttering? ⌄

The 20/20/20 rule states that if you can replace an item for under $20 and find a replacement in under 20 minutes, you should let it go — regardless of how useful you think it might be someday. It was created by The Minimalists to combat "just-in-case" clutter and the fear of getting rid of things you might occasionally need.

What is the 3-3-3 rule for decluttering (Project 333)? ⌄

The 3-3-3 rule — officially called Project 333 — is a minimalist fashion challenge created by Courtney Carver. You choose 33 clothing items (including shoes, outerwear, and accessories, but excluding underwear and workout gear) and wear only those for 3 months, boxing up everything else. After 3 months, you reassess. Most people find they missed very little from the box and feel liberated by a simpler wardrobe.

What are the 4 Cs of decluttering? ⌄

The 4 Cs of decluttering are: Clear Out (remove everything from the space), Categorize (group like items together), Cut Out (decide what to keep, donate, or discard), and Contain (find appropriate storage for what remains). It's a complete process framework rather than a single decision rule, making it ideal for tackling whole rooms or large spaces.

What is the 90/90 rule for decluttering? ⌄

The 90/90 rule asks two questions about any item: Have you used it in the last 90 days? Will you realistically use it in the next 90 days? If the answer to both is no, it's a candidate for donation or disposal. Also popularised by The Minimalists, this rule is especially useful for cutting through emotional attachment by anchoring decisions to actual usage patterns rather than hypothetical future needs.

Which decluttering rule is most effective? ⌄

No single rule is universally "best" — effectiveness depends on your situation. The 20/20/20 rule works best for just-in-case items; the 3-3-3 rule is best for wardrobe clutter; the 4 Cs give you a structured process for whole-room decluttering; and the 90/90 rule is best for stubborn "maybe" items. Many people combine them — using the 4 Cs as a process framework and the 20/20/20 or 90/90 rule as tie-breakers during the "Cut Out" phase.

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Pick One Rule. Start Today.

The best decluttering rule is the one you actually use. Pick the one that resonates most with your current situation, set a 15-minute timer, and begin. The clarity on the other side is worth it.