Paint and Primer Calculator

Paint and Primer Calculator (Ontario)
🎨 Room-by-room estimating Paint + primer + labour + HST

Paint and Primer Calculator

Measure room-by-room, deduct typical doors and windows, and estimate paint and primer based on surface type and coats. Then add labour, supplies, and Ontario HST so the total makes sense before you buy anything.

Jump to calculator Quick FAQ

What this calculator does well

It keeps the math practical: wall area by perimeter × height, ceiling area if you want it, standard opening deductions, and a simple “old walls = more labour” bump. It’s not trying to be a paint-store flyer — it’s trying to be honest.

Tip: primer is often cheaper than an extra finish coat (especially on patchy walls).

Fast measuring cheat-sheet

Walls per room = 2 × (L + W) × H
Ceiling = L × W
Then subtract openings (or use counts, like this calculator).

Keep ~10% extra for touch-ups (it’s the cheapest insurance you’ll buy).

Calculator

Scoped + multi-calculator safe

Paint & Primer Calculator Updates live as you type
Unit system
Choose one
Rooms
Room-by-room
Measure each room separately — same way a painter quotes.
Doors & windows
Deductions
Number of doors (21 sq ft each)
Number of windows (15 sq ft each)
Quality + surfaces
Coverage & pricing
Paint quality
Paint: $65/gal, Primer: $30/gal
Paint ceiling?
Wall condition
Good condition, minimal prep
Surface type
Coverage: 400 sq ft/gallon
Number of coats (paint)
Labour rates (Ontario)
Editable
Walls ($/sq ft)
Typical range: $2–$4/sq ft
Ceilings ($/sq ft)
Typical range: $0.75–$2.50/sq ft
Areas
Totals
Wall area0 sq ft
Ceiling area0 sq ft
Door deduction0 sq ft
Window deduction0 sq ft
Total paintable0 sq ft
Formula: Wall area = 2 × (L + W) × H per room.
Materials
Based on coverage
Primer needed0 gallons
Paint needed0 gallons
Total coats0 coats
Includes 1 primer coat + paint coats. Keep ~10% extra for touch-ups.
Cost breakdown
Ontario HST
Materials$0
Wall labour$0
Ceiling labour$0
Supplies$50
Subtotal$0
HST (13%)$0
Old walls add +25% to wall labour in this model.
Total project cost (incl. HST)
$0
0 rooms • 0 sq ft total
Quick FAQ
Common issues
Do I need primer every time?
Not always. Same-colour repaints on clean drywall often don’t need full priming. But patches, stains, bare wood, and dark-to-light colour changes usually do — primer prevents flashing and saves finish coats.
Why does paint look blotchy after it dries?
Uneven porosity (patches, dusty walls, or unprimed compound). Primer evens absorption so your top coat reflects light consistently.
What’s the fastest way to reduce labour cost?
Do the prep yourself: move furniture, remove plates, tape carefully, fill small nail holes, and sand. Labour is the big ticket item — prep is where hours disappear.