Estimate how much primer you need for a paintable area, based on your coverage rate, number of coats, and a wastage allowance.
Enter coverage according to your primer product.
How to Use the Primer Calculator
Enter your paintable area — use the Paint Quantity Calculator or Wall Area Calculator to work this out first if needed.
Enter your primer's coverage rate, the number of coats, and a wastage percentage.
Click "Calculate" to see the required primer, before and after wastage.
Frequently Asked Questions
Required Primer (L) = Paintable Area × Coats ÷ Coverage. A wastage percentage is then added on top to account for spillage and surface absorption.
It's generally recommended, especially on new or bare walls, repairs, or when changing to a very different color — it improves paint adhesion and finish. Check your paint manufacturer's guidance for your specific surface.
Yes, it's completely free and requires no sign-up.