How many invoice books will you need in a year?
Getting the number roughly right matters more than it sounds. Order too few and you pay a higher price per book and risk running out in the middle of a busy week. Order far too many and the spare books age in a cupboard, and your details may change before you use them.
The formula
Books per year = (invoices per week x working weeks x 1.05) / sets per book
- Invoices per week: look back at a normal month, not your busiest or quietest.
- Working weeks: most small businesses work around 46 to 48 weeks once holidays and Christmas are taken out.
- 1.05: a 5% allowance for spoiled and cancelled sets.
- Sets per book: 100 for our duplicate books, 50 for our triplicate books. Check the number if you are comparing suppliers, because many duplicate books elsewhere hold 50.
Ready reckoner: books needed per year
Based on 48 working weeks and a 5% allowance for spoiled sets, rounded up.
| Invoices per week | Invoices per year | Duplicate books (100 sets) | Triplicate books (50 sets) |
|---|---|---|---|
| 5 | 252 | 3 | 6 |
| 10 | 504 | 6 | 11 |
| 15 | 756 | 8 | 16 |
| 20 | 1,008 | 11 | 21 |
| 30 | 1,512 | 16 | 31 |
| 40 | 2,016 | 21 | 41 |
| 50 | 2,520 | 26 | 51 |
The triplicate column is roughly double the duplicate column for the same number of invoices. That is one reason to choose triplicate only when the third copy is genuinely needed. What is the difference between duplicate and triplicate? helps you decide.
How much should you order at once?
Most businesses do well ordering somewhere between six months' and a year's supply at a time. That balance works for a few reasons:
- Price. Most of the cost of a print job is in setting it up, so the price per book falls as the quantity rises.
- Paper life. Carbonless paper slowly loses sensitivity with age and heat. A year's supply stored in a cool cupboard is fine. Five years' supply in a hot van is not. See Does NCR paper expire, and why are my copies faint?
- Changes. Phone numbers, addresses, VAT status and bank details change. Registering for VAT, in particular, means reordering with a new layout, as How do you invoice as a sole trader in Ireland? explains.
Businesses with more than one van, site or counter
If three people are writing invoices, three books are in use at once, and a single number sequence gets messy. There are two common approaches:
- Separate number ranges. Each van or counter keeps its own book, and the office records which numbers went to which van, so your accountant can see at a glance who issued each invoice.
- One sequence, one book at a time per person, issued from the office and logged. This keeps one sequence but needs someone to track which books went where.
Either works, as long as every number is unique and nothing is skipped. Revenue requires a unique sequential number on every VAT invoice, and a clear system makes gaps easy to explain. If you do end up with a spoiled set, What should you do with a spoiled or cancelled invoice in your book? shows how to handle it.
When to reorder
Reorder when you start your second-last book. With our turnaround, a proof is emailed within one working day and books are dispatched 3 to 4 working days after you approve it, so a reorder placed then arrives well before you run out. Tell us the next number you need, and the new books carry on from there.
Check the sets per book before comparing prices
A price per book means little until you know how many sets are in it. What is a duplicate invoice book? lists what else to check before you order. A 50-set book at a lower price can cost more per invoice than a 100-set book. Divide the price by the number of sets to compare fairly. Our earlier guide What drives the price of duplicate NCR books in Ireland? covers the other factors.
Duplicate books with 100 sets each
Discoverprint's duplicate invoice books hold 100 numbered sets each, so you need half as many books as with 50-set books. The price per book falls as the quantity rises, numbering can continue from your last number, and delivery is free anywhere in Ireland with no minimum spend. Available in A4, A5, A6 and DL. See the full NCR books range.
Read next
Frequently asked questions
- How do I work out how many invoice books I need?
- Multiply the invoices you write in a typical week by the number of weeks you work in a year, add about 5% for spoiled sets, and divide by the number of sets in each book: 100 for a Discoverprint duplicate book, 50 for a triplicate book.
- How many invoices are in one book?
- A Discoverprint duplicate book has 100 sets and a triplicate book has 50. Many other suppliers bind 50 sets in a duplicate book, so check before comparing prices.
- Is it cheaper to order more books at once?
- Usually, yes. Printing costs are front-loaded in setting up the job, so the price per book falls as the quantity rises.
- When should I reorder?
- When you start your second-last book. With a proof in one working day and dispatch 3 to 4 working days after approval, that leaves plenty of time before you run out.
Sources
- Discoverprint: Duplicate invoice books (sets per book, turnaround)
