Drawing a rainbow comes down to two things: getting the colors in the right order and blending them so each band flows into the next. Whether you’re working with crayons, colored pencils, watercolors, or a digital tablet, the core process is the same. Start with a smooth arc, lay down seven color bands from red on the outside to violet on the inside, and blend where they meet.
The Correct Color Order
The classic mnemonic is ROY G. BIV: red, orange, yellow, green, blue, indigo, and violet. Red always sits on the outer edge of the arc, and violet on the inner edge. This matches how light actually bends through water droplets, with red having the longest wavelength and violet the shortest. Many scientists consider indigo too close to blue to be truly distinguishable, so if your drawing looks better with six bands instead of seven, that’s perfectly fine.
If you want to include a faint secondary rainbow outside the main one (a nice touch for realistic scenes), reverse the color order. The secondary rainbow has red on the inside and violet on the outside, and it appears dimmer and wider than the primary arc.
Getting the Shape Right
A rainbow is a section of a circle, not a freehand curve. The simplest way to draw a clean arc is to anchor a string or hold a ruler at a fixed point below your paper and sweep your pencil in an arc. You don’t need to draw the full semicircle. A partial arc poking through clouds often looks more natural than a complete half-circle sitting on the horizon.
For a quick method, draw two concentric half-circles. The outer circle is your red band, the inner circle is your violet band, and you divide the space between them into your remaining color bands. Keeping the bands roughly equal in width gives the cleanest result, though in reality the bands blend into each other without hard edges.
One detail that makes a rainbow drawing look realistic: the light source should be behind the viewer. If you’re drawing a landscape scene, avoid strong side lighting on clouds and trees. Front lighting, as if the sun is at your back, is what you’d actually see when a rainbow appears.
Drawing With Colored Pencils
Colored pencils are one of the most accessible tools for rainbow drawing, and the key technique is layering from light to heavy pressure. Start by laying down each color band with a light touch. Use the side of the pencil rather than the tip for smoother coverage. Light pressure at this stage lets you build up layers gradually and keeps the colors from looking waxy or patchy too early.
Where two colors meet, overlap them. Extend the orange slightly into the red zone and slightly into the yellow zone. Then go back and forth between the two colors in that overlap area, adding thin layers of each until the boundary softens. This is where patience pays off. Three or four light passes blend far better than one heavy one.
Once your gradients look smooth, go back over each color section with firm pressure. This is called burnishing. Pressing hard with the pencil compresses the pigment layers, fills in the paper texture, and makes the colors appear vivid and solid. For added depth, you can lightly shade the edges of each band with a slightly darker version of that color before burnishing. A touch of deeper red along the outer edge of the red band, for instance, gives the rainbow subtle dimension.
Drawing With Watercolors
Watercolors are ideal for rainbows because the medium naturally creates the soft, glowing transitions between colors that make a rainbow look real. The technique to use is wet-on-wet: applying wet paint onto an already wet surface so the colors flow into each other.
Start by lightly penciling your arc shape, then wet the entire rainbow area with clean water using a wide brush. While the paper is still damp, paint your red band along the outer edge. Immediately paint orange next to it, letting the two colors touch and bleed together. Continue inward through yellow, green, blue, indigo, and violet, working quickly enough that the paper stays wet throughout. The colors will spread and merge on their own, creating those soft, dreamy transitions without any hard lines.
Timing matters. If the paper dries before you finish, you’ll get sharp edges where wet paint meets dry paper. If your paper is too wet, the colors will flood together into a muddy wash. The sweet spot is a surface that’s damp and glossy but not pooling. Practice on scrap paper first to get a feel for how quickly your paper dries in your environment.
Drawing Digitally
Digital tools make rainbow arcs easy because you can use ruler guides and adjust everything after the fact. Most drawing apps have a concentric circle ruler or ellipse tool that lets you sweep perfect arcs. Draw each color band on its own layer so you can adjust opacity, width, and color independently.
The trick to making a digital rainbow look luminous rather than flat is using blending modes. Paint your rainbow bands on a layer set to a mode like Screen, Soft Light, or Glow Dodge. These modes let the background show through the color, mimicking how a real rainbow is made of light rather than pigment. Screen mode works well for a subtle, transparent effect. Glow Dodge pushes the brightness further and works for a more dramatic, glowing rainbow against a dark sky.
After placing your color bands, use a soft eraser or a Gaussian blur to soften the edges between them. You can also paint on a separate layer clipped to your rainbow to add brighter highlights along the center of each band, reinforcing that lit-from-within quality.
Common Mistakes to Avoid
- Reversing the color order. Red is always on the outside of the primary rainbow, violet on the inside. Flipping them is the most common error.
- Making bands too uniform and sharp. Real rainbows have soft, gradual transitions. Hard lines between colors make the drawing look like a striped flag rather than a light phenomenon.
- Drawing the arc too flat or too tall. A rainbow is a segment of a circle, so the curvature should be consistent. An arc that flattens in the middle or pinches at the ends looks unnatural.
- Forgetting the surroundings. A rainbow floating in empty space has less impact than one set against a dark cloud, which provides the contrast that makes the colors pop. In real life, the sky inside the rainbow’s arc is slightly brighter than the sky outside it.
Quick Practice Exercise
Grab whatever you have on hand, even basic crayons or markers. Draw two concentric half-circles about two inches apart. Divide the space into seven roughly equal bands. Color them in order: red, orange, yellow, green, blue, indigo, violet, from outside to inside. Where two colors meet, scribble lightly with both colors to blur the boundary. This takes about five minutes and gives you muscle memory for the color sequence and the arc shape. Once that feels natural, try it again with a partial arc emerging from behind a cloud, and focus on making the transitions smoother each time.