Ordering a whole cake in Japan and wondering what "5-go" actually means? Japanese bakeries use the go (号) system — a unique sizing standard based on diameter. This guide covers every go size from 3 to 12, with diameter conversions, serving estimates, price ranges, and slicing tips.
What Is the Go (号) System?
The go system measures a whole cake's diameter and originates from the traditional Japanese measurement unit called sun (寸). One go equals one sun, which is approximately 3 cm (1.2 inches).
The quick formula: go number × 3 = diameter in cm
- 4-go → 4 × 3 = 12 cm (about 5 in)
- 5-go → 5 × 3 = 15 cm (about 6 in)
- 6-go → 6 × 3 = 18 cm (about 7 in)
Cake Size Chart — 3-go to 12-go
A complete reference for whole cake sizes, servings, and typical price ranges in Japan.
Size, servings, and price chart
| Go (号) | Diameter | Servings | Price Range (JPY, incl. tax) | Typical Use |
|---|---|---|---|---|
| 3 | 9 cm (3.5 in) | 1–2 | ¥1,000–2,000 | Solo treat, pet cake |
| 4 | 12 cm (5 in) | 2–4 | ¥2,000–3,500 | Couple, small celebration |
| 5 | 15 cm (6 in) | 4–6 | ¥3,000–5,000 | Family celebration (best seller) |
| 6 | 18 cm (7 in) | 6–8 | ¥4,000–6,500 | Family party |
| 7 | 21 cm (8 in) | 8–10 | ¥5,000–8,000 | House party |
| 8 | 24 cm (9.5 in) | 10–12 | ¥6,000–10,000 | Large gathering |
| 9 | 27 cm (10.5 in) | 12–14 | ¥8,000–12,000 | Large party |
| 10 | 30 cm (12 in) | 14–16 | ¥10,000–15,000 | Wedding, large event |
| 11 | 33 cm (13 in) | 16–20 | ¥12,000–18,000 | Large event (advance order) |
| 12 | 36 cm (14 in) | 20–24 | ¥15,000–22,000 | Extra-large event (advance order) |
Prices shown are for standard shortcakes (whipped cream). Chocolate cakes and fruit-decorated cakes tend to cost 10–30% more.
Reverse Lookup — Choose a Size by Guest Count
Use this table when you know the headcount but not the cake size.
| Guests | Recommended Size | Notes |
|---|---|---|
| 1 | 3-go (9 cm / 3.5 in) | Solo indulgence or taste-testing |
| 2–3 | 4-go (12 cm / 5 in) | Couple or small family |
| 4–5 | 5-go (15 cm / 6 in) | Standard family size — when in doubt, pick this |
| 6–7 | 6-go (18 cm / 7 in) | Extended family gathering |
| 8–10 | 7-go (21 cm / 8 in) | House party |
| 10–15 | 8–9-go | Office or club gathering |
| 15+ | 10-go and up | Wedding or large-scale event |
How Serving Sizes Differ by Cake Type
The same go number can serve different numbers of people depending on the cake type.
Round Whole Cakes (Shortcake, Chocolate, etc.)
The most common type. The chart above applies directly. Standard height is about 7–10 cm.
Tarts
Tarts share the same go diameter as round cakes but are shallower (3–5 cm tall), so servings are 1–2 fewer for the same go number.
| Go (号) | Diameter | Servings |
|---|---|---|
| 5 | 15 cm (6 in) | 3–4 |
| 6 | 18 cm (7 in) | 4–6 |
| 7 | 21 cm (8 in) | 6–8 |
Roll Cakes
Roll cakes are measured by length in centimeters, not by go.
| Length | Servings |
|---|---|
| 15–17 cm | 2–3 |
| 20–22 cm | 3–5 |
| 30 cm+ | 5–8 |
Square Cakes
Square cakes are typically labeled by side length rather than go. When the surface area is similar to a round cake, the serving count is roughly the same.
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Try it now →Slicing Guide by Go Size
Tips for cutting a whole cake into clean, even pieces.
Basic Technique
- Use a sharp knife — a long serrated cake knife works best
- Warm the blade — dip it in hot water and wipe dry before each cut
- Cut in one smooth motion — don't saw back and forth
Recommended Slices per Size
| Go (号) | Diameter | Recommended Slices | Per-Slice Size |
|---|---|---|---|
| 4 | 12 cm | 4 | Generous portion |
| 5 | 15 cm | 6 | Standard portion |
| 6 | 18 cm | 8 | Standard portion |
| 7 | 21 cm | 8–10 | Standard portion |
| 8 | 24 cm | 10–12 | Standard portion |
Equal-Slice Techniques
- 6 slices: Cut in half, then divide each half into 3 (think clock positions: 12, 4, and 8)
- 8 slices: Cut a cross for 4 pieces, then halve each quarter
- 10 slices: Cut in half, then divide each half into 5 (each slice = 36°)
Recommended Sizes by Occasion
Birthday Cake
A 5-go cake is the classic choice for a family of four. There's plenty of surface area for candles. Go up to 6-go for a more impressive look in photos.
Christmas Cake
Advance ordering is essential during the holiday season. 5–6-go for a family dinner, 7-go or larger for a house party.
Wedding Cake
To serve all guests, start at 10-go and above. Multi-tier cakes use different sizes for each layer, so discuss total servings with the pastry chef.
FAQ
What does 'go' (号) mean for cake sizes?
The go system is unique to Japan and comes from the traditional unit sun (寸). One go ≈ 3 cm (1.2 inches) of cake diameter. A 5-go cake is 15 cm (about 6 inches) across.
How many people does a 5-go cake serve?
A 5-go cake (15 cm / 6 in) serves 4 to 6 people. It's the best-selling size in Japan, suitable for family birthdays and casual celebrations.
What size cake should I get for 2 people?
4-go (12 cm / about 5 inches) is ideal. It serves 2–4 people and suits couples or intimate celebrations. If you want generous portions, consider a 5-go.
How does the Japanese go system compare to inches?
One go is about 3 cm. 5-go (15 cm) ≈ 6 inches, 6-go (18 cm) ≈ 7 inches, and 7-go (21 cm) ≈ 8 inches.
Are tarts and roll cakes also measured in go?
Tarts sometimes use go, but because they're shallower, the same go number serves fewer people. Roll cakes use length in centimeters instead of go.
Summary
The key to choosing the right cake size in Japan is the formula go × 3 = diameter in cm. When in doubt, consult the chart above for go number, servings, and price ranges before placing your order.
The 5-go (15 cm / 6 in, 4–6 servings) is the most popular size. If children make up a large share of the guests or everyone loves cake, go one size up.
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Resize images to exact dimensions. Includes presets for social media covers and ID photos.
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