---
title: Cost semantics
description: Understand the date range, segments, four costs, and missing values.
sidebar:
  order: 4
---

## Date range

`month_from` and `month_to` are inclusive ISO dates. `month_to` must not be earlier than `month_from`.

## Product segments

| Value | Meaning |
| --- | --- |
| `normal` | Normal products only. This is the default. |
| `sample` | Sample products only. |
| `all` | Normal and sample products combined. |

## Cost fields

| Field | Product-profit meaning |
| --- | --- |
| `purchase_cost_usd` | Purchase cost from the page's available Landing split. |
| `inbound_freight_usd` | Inbound freight from the same available Landing split. |
| `shipping_to_customer_usd` | Shipping-to-customer total where costed rows exist. |
| `warehouse_fees_usd` | Warehouse-fee total where costed rows exist. |

All four amounts are totals in USD for the requested range.

## `null` versus `0`

- `null` means Mellow could not calculate that cost with the page's current coverage rules.
- `0` means the value was calculated and the result is a real zero.

Do not convert `null` to zero. They represent different business states.

Unmapped source rows remain in the response. Their product ID and SKU may be `null`; clients should not silently discard them.