How much extra should you budget when two children overlap in cloth nappies?

What is “extra” if the first stash is already paid?

The paid-for stash is the first child’s kit. Overlap cost is everything on top while two children still need changes: more nappies in the cupboard, more water and detergent, hotter or more frequent cycles, and more drying space. WRAP (4 March 2015) already assumes siblings can reuse 20–30 modern real nappies. It does not price two in nappies at the same time.

How do I price the extra washes from the machine label?

Ofgem publishes the price-cap unit rate, not a nappy-wash tariff. For 1 July–30 September 2026 the Direct Debit average electricity rate was 26.11p/kWh (the 1 October–31 December 2026 average is 26.32p/kWh). Standing charge is paid whether you wash nappies or not, so it does not belong in the overlap extra.

1. 1
   Read the kWh on the cycle you will use The energy label or the manual lists kWh per cycle for Cotton 40, Eco 40–60 and Cotton 60. Two-in-cloth hygiene at 60°C is the higher of those numbers.
2. 2
   Multiply by the Ofgem unit rate Worked example: 1.5 kWh × 26.11p = about 39p of electricity per load (Direct Debit average, 1 July–30 September 2026). Water and detergent sit on top if you are metered.
3. 3
   Count extra loads in the overlap, not the whole childhood If one child was a wash every other day (~15 loads a month) and two children force a daily wash (~30), the extra is about 15 loads a month. At 39p that is about £5.90 of electricity a month — a worked example, not your machine.
4. 4
   Add the hotter-cycle gap If you move from an eco 40–60 cycle to Cotton 60, subtract the two label kWh figures and multiply the difference by the same unit rate. That gap applies to every load while both children share nappies.
5. 5
   Stop the extra when one child is out of nappies Overlap cost ends when only one child still needs the bucket. After that you are back to the already-paid stash plus a normal wash rhythm.

The Nappy Lady’s May 2023 save-money article priced 60°C cotton cycles on named 8–9 kg machines at about 1.35–1.75 kWh, using 33p/kWh — an old unit rate. Re-run those kWh figures at today’s Ofgem pence. Do not reuse the 67p–115p “cost per wash” totals from that page without updating energy, water and detergent.

How many extra nappies sit in “half as many again”?

Which? (11 February 2026) puts one child at around 15–25 reusables. Half as many again is about 8–13 extra nappies if you take that range literally — the 2016 article’s rule of thumb, not a Which? figure. A toddler already uses the lower NHS change rate (6–8 a day) while a newborn sits at 10–12, so the extra is weighted toward newborn-sized wraps or inserts, not a second birth-to-potty wall of nappies.

Price those extras at what you would pay now. Which? recorded Boots reusables from £9.99 and Ocado Bambino Mio nappies usually around £16 (11 February 2026). Eight extras at those dated shelves is a different bill from eight extras in a supermarket Specialbuy week. The overlap stash is a buy; the extra washes are a monthly.

Does the extra last the whole of the second childhood?

No. Budget the hotter, more frequent washes only for the months both children are in nappies. A one-year overlap at the worked 15 extra loads a month is 180 extra cycles; a three-month overlap is 45. The top-up nappies remain after the older child is out — that buy is not refunded — but the 60°C-and-daily-wash premium stops.

In shortOverlap extra is a half-stash top-up plus more, hotter washes for a limited number of months. Use Ofgem pence and the machine label for energy; use a dated shelf price for the extra nappies. Do not treat “stash already paid” as a zero monthly cost while two buckets are filling.