To increase AC, you can wear items of Armour (1 per body area) Each item of Armour has an AP rating. All worn items of Armour produce a Total AP number.
Armour Point Bonus (APB) is your Total AP minus half (rounded up).
Your AC stat is calculated using the formula 12 + APB + Dexterity Modifier.
If your AP exceeds the total of your Strength x 2, Or the total of your Strength Modifer + Dexterity Modifier – you will become Encumbered.
If your AP exceeds BOTH the total of your Strength x 2 and the total of your Strength Modifier + Dexterity Modifier – you will become Heavily Encumbered.
(It takes 1 Actions per Armour point to Donn or Doth the item of Armour)
Legs:
Light 1 AP: Padded / Leather / Studded leather 5-50 gp | 1-2kg
Medium 2 AP: Splint / Plate / Scale 50-500 gp | 2kg to 3kg
Arms / Hands:
Light 1 AP: Padded / Leather / Studded leather 5-50 gp | 1-2kg
Medium 2 AP: Splint / Plate / Scale 50-500 gp | 2kg to 3kg
Torso:
Light 2 AP: Padded / Leather 15 gp | 2kg
Medium 3 AP: Splint / Studded leather / Chain 150 gp | 3kg
Heavy 4 AP: Plate 1500 gp | 4kg
Head:
Light 1 AP: Leather (hood/cap) 10 gp | 1kg
Medium 2 AP: Chainmail Hood 100 gp | 2kg
Heavy 3 AP: Plate skullcap/helm/bassinet 1000 gp | 3kg
Shields
Shields do not count towards AP or APB, and instead simply add +1 or +2 to AC.
Small Shield +1 AC: 20 gp | 2-4kg
You can use a bonus action to Donn or Doth a Small Shield.
Large Shield +2 AC: 60gp 5-7kg (Strength 15 Required).
You can use a bonus action to Donn or Doth a Large Shield, but it cannot be stored on the body, and must be dropped to the ground, and recovered from the ground.