---
title: "Dry-matter % vs per-1000-kcal ME: converting pet-food nutrient bases"
author: codebuddy
type: article
series: nutrition-standards
desc: "Why pet-food nutrient minimums appear in two bases, the AAFCO 4000 kcal/kg DM assumption, and the arithmetic x2.5 (mass) / divided-by-4 (IU) conversion rule."
source_topics: nutrient_basis_dm_calorie_conversion
date: 2026-08-18
---

# Dry-matter % vs per-1000-kcal ME: converting pet-food nutrient bases

Pet-food nutrient minimums are published in two bases, and knowing how to move between them matters when you compare diets of different energy density.

- **Dry-matter % (DM %)** expresses a nutrient as a percentage of the diet's dry matter, removing moisture distortion.
- **Per 1000 kcal metabolisable energy (per-1000-kcal ME)** expresses the amount per 1000 kcal of the diet's energy — the more robust basis for comparing products of different energy density.

## The 4000 kcal/kg DM assumption

AAFCO 2026 nutrient profiles state the dry-matter basis "assumes 4000 kcal ME/kg DM." Under that assumption the two bases are linked by a fixed factor.

## The conversion rule

A nutrient at **X % DM** equals X g per 100 g DM, i.e. 10X g per kg DM. At 4000 kcal ME per kg DM, each 1000 kcal of diet contains 0.25 kg DM, so:

> **nutrient per 1000 kcal ME (g) = X % DM × 2.5**

For **IU/kg DM**, the factor is ÷4 instead (per-1000-kcal = IU/kg DM × 0.25), because the unit is already per mass rather than per mass-percentage.

## Worked examples (AAFCO 2026 dog adult maintenance)

| Nutrient | DM basis | per-1000-kcal ME basis | Check |
| --- | --- | --- | --- |
| Crude protein (min) | 18.0 % DM | 45.0 g | 18.0 × 2.5 = 45.0 |
| Calcium (min) | 0.5 % DM | 1.25 g | 0.5 × 2.5 = 1.25 |
| Phosphorus (min) | 0.4 % DM | 1.0 g | 0.4 × 2.5 = 1.0 |
| Vitamin A (min) | 5000 IU/kg DM | 1250 IU | 5000 ÷ 4 = 1250 |

## Caveat

The 4000 kcal/kg DM figure is AAFCO/FEDIAF's reference assumption for the DM↔per-1000-kcal conversion. Energy-dense or low-energy diets deviate from it, which is exactly why per-1000-kcal ME is the preferred basis whenever you are judging "is this food enough" across products of different energy density.

## Sources

- `nutrient_basis_dm_calorie_conversion` — the 4000 kcal/kg DM assumption, the ×2.5 (mass) / ÷4 (IU) derivation, and the four verbatim AAFCO 2026 dog adult paired values above.