Method · The 9-Staple Basket
What's in the basket, and how we cost it.
A short, audit-friendly guide to every number on the basket page.
The nine staples
The basket is fixed — same nine items every week — so changes in the published figure track real price movement, not basket churn. The ingredients and the standard weekly quantity we cost are:
- Butter500g
- Cheddar cheese500g
- Eggs1 dozen
- Bread1 loaf (~700g, rounded to kg)
- Chicken thigh1kg
- Beef mince1kg
- Bananas1kg
- Capsicums500g (~3 capsicums)
- Broccoli400g (~1 head)
SKU policy.At each supermarket, for each staple, we use the cheapest valid pack — where valid means an AI-classifier has confirmed the product matches the canonical, the pack hasn’t been added to our denylist for a known mismatch, and the SKU is currently in stock in the online catalogue. Pack price is never the input number; we cost on a per-kg / per-litre / per-each basis throughout.
HH=4 purchase frequency table
The weekly basket figure on /watch/groceryindex is built bottom-up: per-pack price × packs per week, summed across the nine staples. The packs-per-week numbers below are Kepie editorial estimates, not measured user data — we’ll refine per-issue as cooking telemetry from authed app users thickens. Holding the table visible is the point: every line of the basket headline is traceable to one row here.
| Staple | Packs / week (HH=4) | Why this number |
|---|---|---|
| Bread (700g loaf) | 2.5 | sandwiches + toast at HH=4 |
| Butter (500g block) | 0.5 | one 500g block ≈ 2 weeks |
| Cheddar (1kg block) | 0.4 | one 1kg block ≈ 2.5 weeks |
| Eggs (1 dozen) | 1.5 | breakfasts + baking |
| Mince (500g) | 1.5 | one Bolognese + one taco/burger |
| Chicken thigh (1kg) | 1.5 | one tray-bake + one stir-fry |
| Bananas (1kg) | 1.0 | snacks + lunchbox |
| Capsicum (each) | 3.0 | salads + roasts |
| Broccoli (head) | 1.0 | one mid-week dinner side |
The two-thirds gap
NZ media consensus and the most recent Stats NZ Selected Price Indexes put typical weekly grocery spend for a household of 4 at roughly $250–$330(May 2026). Our 9-staple basket sits at roughly two-thirds of that figure — the rest is everything not in the nine staples we track (pasta, rice, oil, sugar, flour, frozen veg, tea, coffee, snacks, cleaning, lunchbox items, fresh fruit beyond bananas). We don’t try to cost a whole weekly shop because we can’t audit it honestly week-on-week. The corpus grows every issue.
Source consensus (the basis of the $250–$330 anchor):
- Steady NZ 2026 — grocery budget research (accessed 27 May 2026)
- MoneyBalance 2026 — NZ household budget data (accessed 27 May 2026)
- Stats NZ Selected Price Indexes — April 2026 (accessed 27 May 2026)
- Foodstuffs press release — May 2026 (accessed 27 May 2026)
- RNZ — March 2026 cost-of-living coverage (accessed 27 May 2026)
Date discipline
Every issue follows the same rhythm — we publish on Sunday morning; the prices on the page are the snapshot we captured the prior Friday. The week-ending date is always the publish-Sunday. We never back-date and we never publish numbers measured after the publish date.
Other household sizes
HH=4 is our default audience anchor. When the page shows other household sizes, we apply a locked scaling table — HH=1 ×1.0, HH=2 ×1.7, HH=3 ×2.4, HH=4 ×3.1, HH=5 ×3.6 — sourced from the same NZ household budget research that pegs the typical-spend range. Scaling is multiplicative, not item-by-item; we label every scaled figure as scaled-from-HH=4.
Known limitations
- Frequency table is editorial-estimated, not measured user data.
- HH scaling factors are approximate; large households have more shape variability than the table can express.
- Price history is currently five weeks deep — we suppress week-on-week / month-on-month / year-on-year deltas until twelve weeks.
- The basket excludes long-tail grocery items (~one-third of typical spend).
- We measure online catalogue prices, not in-store specials or clearance markdowns.