Practical guide · Reviewed September 14, 2026
Why rounding packs together matters
Retail materials are usually sold in complete boxes or tins. A decimal area estimate is not a purchase quantity. The practical rule is to add compatible needs first, then divide by the coverage of one pack and round upward.
A two-room example
Two rooms of 9 m² each need 9.9 m² each after 10% allowance. Packs cover 3 m². Separate orders round each room up to 4 packs, giving 8 packs total. A combined order needs 19.8 ÷ 3 = 6.6 packs, rounded up to 7. The combined order covers 21 m².
Pooling does not always save a pack. For example, 12 m² and 9 m² rooms with 10% allowance and 2.2 m² packs need 6 and 5 packs separately, and 11 together. RoomLedger calculates the actual order; it does not promise automatic savings.
What can be pooled?
Only identical, compatible materials with combining enabled on every contributing row. Product name, material type, units, pack coverage and price must match in RoomLedger. Paint coverage must match too. Name different colours, finishes and product batches separately. Never pool quantities simply because both rows say “paint”.
Surplus is not installation waste
The app shows remaining material after the planned allowance. It does not predict the real amount of usable leftovers. Keep the manufacturer's recommended spares for future repairs.
Arithmetic examples are illustrative. Verify measurements and the product label before purchasing.
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