How to Write a Purchase Order: Core Fields, Examples, and Common Mistakes

A purchase order is how you tell a supplier exactly what you want to buy, at what price, and when you need it. When they accept it, you both have a binding record of the deal. But a PO that's missing key fields or uses vague language will cause delays, wrong shipments, and invoice mismatches. Here's what to include, how to write one, and the mistakes to avoid.

The 8 Core Fields Every Purchase Order Needs

Every useful PO—whether you email it, submit it through a supplier portal, or send it via WhatsApp—must include these eight fields. Skip any of them and you're sending a request, not an order.

Field	What to put
Buyer name and address	Your business name and physical or billing address
Supplier name and address	Their legal business name and the location you're ordering from
PO number	A unique reference, e.g., PO-2026-0042. Use this on every related document
PO date	The date you issue the order
Ship-to location	Where the goods go. Can differ from your billing address
Line items	Each item on a separate row with description, quantity, and unit price
Quantity	Always include the unit of measure (each, case, pallet, kg)
Total amount	The sum of all line items before tax and shipping

Fields That Prevent Disputes

The eight core fields get you a basic order. Adding these five fields cuts the back-and-forth dramatically. One retailer we worked with saw order errors drop from about 8 per month to 1 after adding them.

• Required delivery date or window. "ASAP" means nothing to a supplier with a route schedule. Specify "Deliver by April 15" or "Delivery window April 12–15."
• Supplier part number (SKU). Use their SKU, not yours. If you order off your internal code, they have to translate it—and that's where substitutions and wrong items come from.
• Pack size and unit of measure. "1 case of 12" vs "1 each" is the single most common source of order errors. Be explicit: "1 case (12 units)."
• Substitution policy. State it clearly: "Do not substitute" or "Substitute up to $50 and notify before shipping." Pick one.
• Acceptance trigger. "Please confirm by 5pm Thursday or this order is void." This prevents you from waiting on stale orders that never got processed.

How to Write a Purchase Order: A Short Example

Here's a real-world example for a cafe ordering supplies.

PO-2026-0042 | Date: March 1, 2026

Buyer: Sunrise Cafe, 123 Main St, Austin, TX 78701
Supplier: Texas Coffee Roasters, 456 Oak Ave, Austin, TX 78702
Ship to: Same as buyer
Delivery by: March 10, 2026

Item	Supplier SKU	Qty	Unit	Unit Price	Total
Colombian beans, dark roast	TCR-1001	2	case (12 bags)	$48.00	$96.00
Ethiopian beans, light roast	TCR-1022	1	case (12 bags)	$54.00	$54.00

Total: $150.00
Payment terms: Net 30
Substitution policy: Do not substitute
Special instructions: Call 30 min before arrival. Use rear loading dock.

6 Common Purchase Order Mistakes

Avoid these and you'll save hours of reconciliation time.

1. No PO number. When the invoice arrives, you can't match it. Always assign a unique number before sending.
2. Ambiguous quantity and pack. "1 strawberries" means one flat to one supplier and one case to another. State the unit.
3. Using your SKU instead of the supplier's. Forces a translation step that often goes wrong. Use their part number.
4. No delivery date. The supplier defaults to their preference, which may not match yours.
5. No payment terms. Defaults to COD or prepaid for new buyers. Always state Net 30, Net 60, or whatever you've agreed.
6. Currency not stated. For cross-border orders, assuming USD when the supplier works in EUR costs you 2–5% on the exchange rate. Write it clearly.

How to Send Your PO

How you transmit the PO matters for your audit trail and speed.

• Email with PDF attachment. Works for most suppliers. Keep a sent folder for records.
• Supplier portal. Fine for one supplier. A pain when you have twenty different logins.
• WhatsApp. Common in B2B, especially Latin America and Asia. Modern systems can format POs as structured messages.
• EDI (Electronic Data Interchange). Best for high-volume relationships. Automates the whole flow.

Avoid phone or fax as your primary channel—you have no written record if a dispute arises.

The Legal Side (In Plain English)

This is practical guidance, not legal advice. A PO is generally treated as an offer to buy. It becomes a binding contract when the supplier accepts—either explicitly (a written confirmation) or implicitly (shipping the goods or sending an invoice). Keep your PO as the controlling document, and always reference the PO number on invoices and packing slips.