Ladder Height Calculator
Using a ladder that's too short for the job is one of the most common causes of falls, forcing you to overreach or balance on the top rungs. Enter the height you need to reach below and we'll work out a safe ladder length and base distance using the standard 1:4 rule.
Work out the right ladder length
Enter the height you need to reach and we'll work out a safe ladder length and base distance.
Position the base 0.75m from the wall (the 1:4 rule) for a safe leaning angle of around 75°.
Use at least a 4m ladder
That covers a required reach of 3.09m along the ladder itself, measured from the ground to the top support point.
Recommended products
A few well-reviewed ladders for outdoor and DIY use.
- Aluminium
- Indoor DIY
- 7-Step
£106.80
Pros
- Lightweight aluminium is easy to carry and store
- High handrail and large platform improve stability
- EN131 rated for professional use
Cons
- Aluminium can feel cold to grip outdoors in winter
- Fibreglass
- Electrical work
- 6-Step
£151.99
Pros
- Non-conductive fibreglass is safe for electrical work near consumer units
- Wide platform improves stability for longer jobs
- Platform height of 1.40m gives a safe working height of around 3.15m
Cons
- Heavier to carry than an aluminium equivalent
- Higher price reflects the electrical-safe build
- Steel
- Indoor DIY
- 2-Step
£24.99
Pros
- Cheap and compact for quick jobs around the house
- EN14183-certified 150kg load capacity
- Folds flat for storage under stairs or in a cupboard
Cons
- Not rated for outdoor or trade use
- Limited reach for taller ceilings
Frequently asked questions
What is the 1:4 rule for ladders?
The 1:4 rule is the HSE-recommended safe angle for a leaning ladder: for every 4 units of height, the base should be positioned 1 unit away from the wall. This gives an angle of around 75 degrees, which is stable enough to prevent slipping without being so steep that the ladder can tip backwards.
How much of the ladder should extend above the point I’m stepping onto?
When using a ladder to access a roof, gutter or platform, it should extend at least 1m above the landing point so you have something secure to hold onto while stepping on or off.
Should I always round up to the next ladder size?
Yes — a ladder that’s slightly too short leaves you overreaching or standing on the top rungs, both of which are common causes of falls. A slightly longer ladder is easy to use safely; a slightly short one is not.
Do I need a different type of ladder for different jobs?
Stepladders suit indoor jobs and lower-level outdoor tasks where a free-standing ladder is safer than leaning one against a wall. Leaning (pole) ladders suit gutter and roof access. Combination or multi-position ladders can convert between the two.