Diamond Painting Drill Count Calculator
Diamond painting covers a canvas with tiny resin drills set on a fixed grid. To order enough beads you need to know how many drill positions your canvas holds, which is simply the canvas width and height divided by the drill size. This calculator multiplies the column count by the row count to give the full-drill total, then adjusts for partial coverage, a spare-drills waste allowance, and your kit's drills-per-bag figure. All measurements use millimeters for the drill pitch and centimeters for the canvas, the standard sizing for diamond painting kits, so you can match a supplier's numbers exactly.
Drill count formula
columns = floor(width_mm / pitch)
rows = floor(height_mm / pitch)
full positions = columns * rows
covered = full positions * (coverage / 100)
drills needed = covered * (1 + waste / 100)
bags = ceil(drills needed / drills per bag)
Canvas dimensions are converted from centimeters to millimeters (1 cm = 10 mm) before dividing by the drill pitch. The grid count uses whole drills only, so fractional edge positions are dropped.
Using the result
- Square drills sit edge to edge with no gaps; round drills are the same pitch but leave small visible spaces.
- Full-drill kits cover the whole canvas; partial kits cover only the subject, so lower the coverage percentage.
- The total is split across many colors, so per-color counts come from the kit's symbol chart, not this overall figure.
- A 5 to 10 percent waste allowance covers dropped, lost, and off-color drills and gives spares for touch-ups.
- Drills-per-bag varies widely between suppliers; confirm the count for your specific kit.
Diamond painting drills: frequently asked questions
How many drills fit in one inch?
It depends on the drill size. Standard square drills measure about 2.5 mm, which is roughly 0.0984 inch, so about 10.16 drills fit per inch (25.4 mm / 2.5 mm). Round drills are the same size but leave small gaps. This calculator divides your canvas dimensions by the drill pitch you enter, so you can match your kit exactly.
How is the total drill count calculated?
The grid is the canvas width divided by drill size, times the canvas height divided by drill size. For a 30 cm by 40 cm canvas with 2.5 mm drills, that is 120 columns times 160 rows, which equals 19,200 drill positions on a fully covered (full-drill) canvas.
How many drills come in a bag?
There is no industry standard. Bags are sold by weight or count and commonly hold a few hundred drills. Enter your kit's drills-per-bag figure so the bag estimate matches your supplier. Roughly 200 to 700 drills per bag is typical, but always confirm with your kit.
Does partial drill coverage change the count?
Yes. On a partial-drill canvas only part of the surface is beaded. Set the coverage percentage below 100 percent to scale the total down. A 60 percent coverage canvas needs about 60 percent of the full-drill count.
Why add a waste allowance?
Drills are lost, dropped, or come misshapen, and you want spares to match colors later. A waste allowance of 5 to 10 percent is a common buffer. This calculator multiplies the base count by one plus your allowance so you order enough.
Official sources
- U.S. National Institute of Standards and Technology: Office of Weights and Measures (millimeter and centimeter definitions).
- NIST: National Institute of Standards and Technology (SI unit conversions).
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.