You've found the perfect pendant lights for your kitchen. The tile samples are sitting on your benchtop. You're ready to start your renovation — until you open a spreadsheet and realise you have no idea how to actually budget for this thing.

You're not alone. According to research from Hippo, 38% of homeowners underestimate the cost of their DIY projects. And Today's Homeowner reports that 34% of renovators go over budget specifically due to poor cost estimation.

The good news? Creating a realistic budget isn't complicated. It just requires a system that accounts for how renovations actually unfold — not how we wish they would.

Why most DIY budgets fail

Most budgets fail before the first nail is hammered. Here's why:

We budget for the dream, not the reality. You price out the beautiful herringbone tiles but forget about the underlayment, the grout, the tile spacers, and the sealer. Those "small" additions can add 30% to your materials cost.

We don't account for the things we can't see. Open up a wall and you might find outdated wiring, water damage, or framing that doesn't meet code. These surprises aren't rare — they're practically guaranteed in older homes.

We underestimate our own time. When a weekend project stretches into month three, you're suddenly paying for takeaway meals, childcare, and the opportunity cost of not doing other things.

We use the wrong tools. Spreadsheets are great for tracking numbers you already know. They're terrible for adapting to a project that changes weekly.

The 35-30-20-15 rule for budget allocation

Before you price a single item, decide how you'll allocate your total budget. Here's a framework that works:

35% — Materials

This is your core spend: tiles, timber, fixtures, paint, hardware. For most DIY projects, materials should eat about a third of your budget.

Tips for this category:

Get three quotes for major materials
Factor in 10% waste for cuts and mistakes
Don't forget consumables (sandpaper, tape, brushes)

30% — Labour (even for DIY)

Wait, it's DIY — why budget for labour?

Because you'll likely need help somewhere. Maybe it's the electrician who needs to sign off on your work. Maybe it's the plumber for anything involving gas. Maybe it's paying a mate to help lift that 80kg benchtop.

Even if you're doing everything yourself, value your time. If you're taking unpaid leave from work, that's a real cost.

20% — Tools and equipment

Don't own a tile cutter? Never bought a paint sprayer? Tools add up quickly.

Consider:

Which tools can you hire instead of buy?
Which tools are worth owning for future projects?
Don't forget safety equipment (goggles, masks, gloves)

15% — Contingency

This is non-negotiable. Every renovation has surprises, and according to Emily Henderson via Good Housekeeping, unexpected issues are the number one reason projects blow their budgets.

Contingency isn't "money you probably won't spend." It's "money you will definitely spend on something you can't predict."

Hidden costs most people forget

Beyond the 35-30-20-15 split, watch for these budget-killers:

Council permits and inspections. Depending on your project, you might need a building permit, a development application, or both. Fees vary widely by council, so check early.

Skip bin hire. Old cabinets, carpet, and rubble need to go somewhere. A skip for a kitchen reno can cost $300-600 depending on size and location.

Temporary fixes. No kitchen for three weeks? Budget for eating out or a temporary cooking setup. Bathroom out of action? Factor in gym memberships for showers or portable toilet hire.

Storage. If you're emptying a room, you might need temporary storage. Even a small unit runs $100-200 per month.

Finishing touches. Paint the walls and suddenly your old light switches look dated. Redo the floors and the skirting boards need replacing. Budget for the cascade effect.

Your own mistakes. Cut a tile wrong? Order the wrong shade of paint? These happen to everyone. Build in a "learning tax."

Step-by-step budget creation process

Here's how to build a budget that survives contact with reality:

Step 1: Define your scope (and stick to it)

Write down exactly what you're doing. Not "renovate the bathroom" but:

Replace shower screen with frameless glass
Retile floor and shower walls
Install new vanity and mirror
Replace tapware with matte black fixtures

Scope creep is real. A written scope helps you say "that's a different project."

Step 2: Research everything before committing

Before you buy anything, price your entire project:

Visit hardware stores and suppliers
Get quotes for any trade work
Check tool hire rates
Research permit costs with your local council

Create a complete list before spending a dollar.

Step 3: Apply the 35-30-20-15 split

Take your total budget and allocate it across the four categories. If materials are coming in at 50%, you either need a bigger budget or a smaller scope.

Step 4: Build your line-item breakdown

Now get granular. List every item you need with:

Description
Estimated cost
Supplier
Whether it's essential or nice-to-have

The nice-to-have items are first to go if budget pressure hits.

Step 5: Track as you go

A budget isn't a document you create once. It's a living thing that needs weekly updates. Every expense should be logged, compared against your estimate, and reflected in your remaining contingency.

Why spreadsheets fall short for DIY projects

Spreadsheets feel like the obvious choice. But they have real limitations for renovation tracking:

They're not designed for changes. Renovations evolve constantly. Spreadsheet formulas break when you add rows, move columns, or change categories.

They can't handle receipts. Where do you store that bunnings receipt? A spreadsheet can hold the number, but not the photo. You end up with a folder of images that aren't linked to anything.

They don't show progress visually. You can calculate percentage complete, but seeing a progress ring fill up hits differently than a cell showing "67%."

They require discipline you might not have. Let's be honest — if you were great at spreadsheet admin, you probably wouldn't be searching for budget help.

They don't travel well. At the hardware store, you need to know: have I already bought tile adhesive? What size grout float did I budget for? Spreadsheets on phones are not a fun experience.

A simpler approach

Task n Tally was built for exactly this problem. It's a single app where you can:

Set a project budget and see how much you've spent at a glance
Photograph receipts when you log expenses
Track tasks alongside your spending
See visual progress without mental arithmetic
Access everything from your phone while you're at Bunnings

No formulas to break. No files to sync. Just one place for your entire project.

If you're tired of wrestling with spreadsheets while trying to tile a bathroom, it might be worth a look.

Start your project for free →

Quick reference: DIY budget checklist

Before you start spending, make sure your budget includes:

[ ] All materials with 10% waste buffer
[ ] Trade costs (even for "DIY" projects)
[ ] Tool purchases and hire
[ ] 15-20% contingency fund
[ ] Permit and inspection fees
[ ] Waste removal costs
[ ] Temporary living arrangements
[ ] Finishing touches and cascade items
[ ] A system to track it all as you go

Get the budget right, and the renovation becomes a lot less stressful. Get it wrong, and you're another statistic in the "went over budget" column.

The difference is usually just preparation.

How to Create a Realistic DIY Renovation Budget (Without the Spreadsheet Headache)