Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Total blocks needed
300
Courses (rows) high
4
Estimated block cost
$1,050
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter wall length (ft).
- 2Enter wall height (ft).
- 3Enter block width (in).
- 4Enter block height (in).
- 5Enter price per block ($).
- 6Read your total blocks needed on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Retaining wall block counts depend on wall length, height, and the size of the block you're using. This calculator defaults to a 100-foot wall at 2 feet tall using a common 16-inch by 6-inch block face, calculating the number of courses needed to reach the target height and the total blocks for the full run, plus an estimated material cost.
Worked example
Using the values the calculator loads with:
Inputs
- Wall length: 100 ft
- Wall height: 2 ft
- Block width: 16 in
- Block height: 6 in
- Price per block: 3.5 $
Results
- Total blocks needed: 300
- Courses (rows) high: 4
- Estimated block cost: $1,050
What each field means
Inputs
- Wall length (ft)
- The wall length used in the calculation, measured in ft. Starts at 100 ft so you have a working example on load.
- Wall height (ft)
- The wall height used in the calculation, measured in ft. Starts at 2 ft so you have a working example on load. Accepted range: 0.5–10 ft.
- Block width (in)
- The block width used in the calculation, measured in in. Starts at 16 in so you have a working example on load. Accepted range: 6–24 in.
- Block height (in)
- The block height used in the calculation, measured in in. Starts at 6 in so you have a working example on load. Accepted range: 3–12 in.
- Price per block ($)
- The price per block used in the calculation, measured in $. Starts at 3.5 $ so you have a working example on load.
Results
- Total blocks needed
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Courses (rows) high
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated block cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How many blocks are in one course of a 100-ft wall?
With a 16-inch block, about 75 blocks per course — narrower blocks require more per course, and this calculator recalculates automatically for your block size.
Do I need gravel backfill behind a retaining wall?
Yes, a gravel drainage layer behind the blocks is essential to relieve hydrostatic pressure and prevent the wall from bowing or failing over time.
How tall can a retaining wall be without engineering?
Most jurisdictions require an engineered design and permit above 3-4 feet; check local codes before building anything taller than that.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). 100 Ft Retaining Wall Blocks Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/100-ft-retaining-wall-blocks-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/100-ft-retaining-wall-blocks-calculator" target="_blank" rel="noopener">100 Ft Retaining Wall Blocks Calculator — RevenueLab</a> (2026).</p>
Source: [100 Ft Retaining Wall Blocks Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/100-ft-retaining-wall-blocks-calculator) (2026).