How much wash do I need to mix?

Always mix more than you think you need — running out mid-wash creates a hard edge that is nearly impossible to fix. By default this calculator adds a 50% safety margin (adjustable under Advanced Options). For large or unbroken washes, err on the side of too much. The coverage figures are practical studio estimates, not exact constants — actual paint use varies with brush, paper sizing and how wet you work.

What is the difference between wash types?

A flat wash has even colour across the area. A graded wash transitions from strong to light (or vice versa). A variegated wash blends multiple colours. Graded and variegated washes use slightly more paint due to overlapping strokes.

How do I mix a wash correctly?

Put water in a clean container first. Add concentrated paint gradually, stirring thoroughly. Test on scrap paper. The colour should be slightly darker than desired — watercolour lightens by 20-30% when dry.

What dilution should I use?

Light washes (transparent tints) use about 5% paint to water. Medium washes (standard) use 10%. Strong washes (deep colour) use 20%. The more transparent the wash, the more water you need.

Can I save leftover wash?

Yes — store in a sealed container and it will keep for days. The pigment may settle — stir before reuse. Diluted washes are also useful for tinting subsequent layers or mixing new colours.

ArtCalcs

Wash Size Calculator — Watercolour Wash Volume

Calculate the volume of diluted watercolour paint needed for a flat or graded wash.

Wash Width

Width of the area to be washed (e.g. the paper or sky region)

Wash Height

Height of the area to be washed (top to bottom of the wet zone)

Wash TypeFlat = even tone; Graded = strong-to-light transition; Variegated = blend of multiple colours

DilutionDilution ratio with water or medium

How We Calculate This

How Wash Calculation Works

Solution volume = Area × Coverage rate × Wash-type multiplier × safety factor

The coverage rate depends on dilution (light, medium, strong) and works out to roughly 120–200 ml of wet diluted wash per square metre — a practical studio estimate rather than an exact constant, since real paint use varies with brush, paper sizing and how wet you work. Graded washes use 20% more and variegated washes 30% more than a flat wash by default. A 50% safety margin is added on top (adjustable under Advanced Options) because running out of wash mid-application is the most common watercolour mistake.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.