AtlasCalcsUtility Calculation Suite
2026-09-23 8 min read

Rise and Run Calculator

Free rise and run calculator — convert rise and run to slope percent, ratio and angle for ramps, roofs and drainage. Includes live results, step-by-step working, charts, material takeoff and cost estimates. No sign-up.

Calculator

Rise(same unit) Help
same unit

Vertical change

Run(same unit) Help
same unit

Horizontal distance

Slope breakdown

ItemAmount
SlopeRise ÷ run × 1008.33 %
AngleFrom horizontal4.76 °
Rise per foot of runUnit slope0.0833 ft
Run per unit riseGentleness figure12.00 : 1

How to use this result

  • Primary result: 8.33 % — verify it against a rough hand check before ordering.
  • Read the steps section to see every conversion and the exact formula path.
  • Use the breakdown table on the left as your order or bid checklist.
  • Re-run with worst-case dimensions so the plan covers the whole job.

Results

Normal

Slope

8.33%

Rise ÷ run × 100

Angle

4.76°

arctan(rise ÷ run)

Rise per 12 in run

1.000in

Roof-pitch style figure

Run per 1 unit rise

12.000:1

Horizontal per unit vertical

Live results update as you type — currently showing 8.33 %. Replace the defaults with your own measurements for exact results.

Visualizations

Your slope vs benchmarks (%)

8.3Your slope
8.3ADA max ramp
33.34:12 roof
10045°

Rise vs run

Rise8%
Run92%

Formula

Slope percent is rise divided by run times 100; the angle is the arctangent of the same ratio.

slope % = rise ÷ run × 100

Variables

SymbolNameUnitDescription
rise, runRise and runsame unitVertical change and horizontal distance.
%Slope percent%Rise ÷ run × 100.
θAngle°arctan(rise ÷ run) from horizontal.

Explanation

The ratio rise ÷ run is computed at full precision, then expressed as percent, angle and ratio forms — three views of one geometry.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Divide rise by run for the slope ratio.

slope = 2 ÷ 24
Result: slope = 0.0833
Step 2

Convert to percent and angle.

0.0833 × 100; arctan(0.0833)
Result: 8.33% · 4.76°
Final Answer
8.33

Worked Examples

See how the calculator works with different scenarios.

Scenario

The calculation run on the values above, showing the full path rather than only the answer.

Inputs

Result:8.33 %

Calculation

1. Divide rise by run for the slope ratio. → slope = 0.0833 2. Convert to percent and angle. → 8.33% · 4.76°

Result

8.33 %

Interpretation

For drainage, hold 2% (≈1/4 in per foot) away from foundations; for ramps, never exceed 8.33% without landings and rails.

Understanding Your Result

Your Result: Slope: 8.33 %

Typical range: ADA ramp max 8.33% · driveway max ~15% · 4:12 roof 33% · 45° equals 100%.

What This Means

Your result is 8.33 % — the slope percent, ratio and angle from your rise and run

Why It Matters

Slope controls drainage, ramp compliance, roof pitch, stair comfort and excavation stability. A misread slope fails inspections or floods slabs.

Professional Interpretation

For drainage, hold 2% (≈1/4 in per foot) away from foundations; for ramps, never exceed 8.33% without landings and rails.

How this is calculated

Percent slope is rise ÷ run × 100; the angle is arctan(rise ÷ run); the ratio form is run per unit rise. All three describe the same geometry.

What drives the result

The inputs in a single consistent unit and the allowance or price you apply.

Recommendations

  • •Verify critical dimensions on site before ordering.
  • •Keep one unit throughout each calculation.
  • •Add the trade allowance before buying, not after.
  • •Attach the step-by-step working to bids and records.

Educational Content

Introduction

Rise over run is the universal language of slope: one ratio describes a wheelchair ramp, a roof pitch, a sewer fall and a hillside grade alike.

Concept Explanation

Percent slope is rise ÷ run × 100; the angle is arctan(rise ÷ run); the ratio form is run per unit rise. All three describe the same geometry.

Applications

▸Quantity takeoffs and material ordering
▸Bids, estimates and change orders
▸Plan checks and site verification
▸Cost control against measured quantities
▸Handover documentation with a clear paper trail

Benefits

  • •Instant results with the full working shown
  • •Exact unit conversions built in
  • •Charts and breakdown tables for bids
  • •Free, no sign-up, works on site from a phone

Limitations

  • •Two-dimensional math unless stated otherwise — slopes and curves need the right tool
  • •Results are only as good as the site measurements
  • •Allowances and prices are estimates — confirm with local quotes

Best Practices

  • •Measure twice and write measurements down before typing them in
  • •Keep one unit throughout each calculation
  • •Photograph the tape on large or disputed measurements
  • •Re-run with worst-case numbers so the plan covers the whole job

Common Misconceptions

Myth: The calculator replaces site verification.
Truth: It replaces the arithmetic, not the tape measure — always verify before ordering.
Myth: One decimal place is always enough.
Truth: On long runs, rounding early compounds. Enter full measurements and let the tool round at the end.
Myth: Metric and imperial give different answers.
Truth: They are the same physical quantity in different units — conversion is exact.

Practical Tips

  • •Enter full measurements and let the tool round at the end.
  • •Use the steps section to double-check the formula path.
  • •Save or share the result link with the crew and the supplier.
  • •Re-run with worst-case dimensions for a safe order.

Common Mistakes

Rounding measurements before calculating.
Enter the full tape reading; rounding early compounds across a job.
Mixing units between fields.
Pick one unit in the dropdown so every conversion is consistent.
Forgetting to verify on site.
Plans differ from as-built work — confirm critical dimensions.
Ordering the bare result with no allowance.
Add the trade waste or contingency factor before buying.

Assumptions

This calculator makes the following assumptions to provide estimates:

Consistent units: All inputs share the selected unit system.
Standard geometry: Flat-plane Euclidean formulas unless stated.
Full precision: Rounding happens only on display, never mid-calculation.

Limitations

Be aware of these limitations when using this calculator:

Estimates, not quotes: Allowances and unit prices vary by region — get 2–3 local quotes.
Verify on site: Confirm critical dimensions before ordering or cutting.

Frequently Asked Questions

Answers to common questions about this calculator.

How do I calculate slope from rise and run?
Divide rise by run and multiply by 100 for percent. A 2 ft rise over 24 ft run is 8.33% — the ADA ramp maximum.
What units do rise and run use?
Any unit, as long as both match. Inches, feet or meters all give the same percent and angle.
What is the difference between slope percent and degrees?
Percent is rise ÷ run × 100; degrees is arctan(rise ÷ run). 100% equals 45°, and they diverge fast past that.
How do I express slope as a ratio?
As run per unit of rise — e.g. 12:1 for an ADA ramp. The calculator shows it live.
What slope needs a handrail or specialist design?
Ramps above 8.33% need handrails and landings under accessibility rules; anything near or above 100% (45°) needs engineered design.
How is roof pitch related to rise and run?
Pitch is rise per 12 inches of run — a 4:12 pitch is 33.3%. The rise-per-12 row shows it.
Can run be zero?
No — a vertical face has undefined slope. Enter a small positive run or treat it as a wall.
How accurate is this calculator?
Exact for the numbers entered. Field accuracy depends on level and tape technique.
What slope drains water without eroding?
About 2% minimum to move water, up to roughly 33% (3:1) for vegetated slopes. Between those, pipes and swales carry it.
What is the maximum ramp slope for wheelchairs?
1:12 (8.33%) with landings, edge protection and handrails under ADA rules. Anything steeper is not an accessible route.
What grade can cars climb on a driveway?
About 12–15% maximum in most codes, with flattened transitions top and bottom so bumpers clear. Icy regions stay nearer 8–10%.
How steep can excavators and dozers work?
Manufacturer limits vary, but sustained work above roughly 30–35% needs purpose-built machines, winch assist or benching. Never guess — check the manual.
How do I measure slope in the field?
Level and rod for short runs, clinometer or phone level for quick checks, laser level for grading. Two readings and the distance give percent.
What is cross-slope and why does it matter?
Side-to-side grade across walks and roads — typically capped near 2% so wheelchairs track straight while water still sheds.
How does slope affect excavation quantities?
Sloping and benching widen every trench and pad, multiplying dig volume. OSHA protection starts at 5 ft depth.
Can slope exceed 100%?
Yes — percent passes 100 beyond 45 degrees. A 200% grade is about 63 degrees. Percent and degrees are not proportional.
How do I hold grade during grading?
Set grade stakes with cut/fill marks, check with a level or laser as work advances, and re-check after compaction — settlement steals grade.
What if my site conditions differ from the page defaults?
Defaults are worked examples, not recommendations — replace every input with your own measurements, prices and allowances before ordering or bidding.
How do I budget for price changes mid-project?
Lock supplier quotes in writing with expiry dates, carry a 5–10% escalation contingency, and re-run the calculator when prices move. Volatile materials get shorter quote windows.
Should I buy materials in bulk for this job?
Bulk wins when storage is dry and secure, the material keeps, and the discount beats carrying cost. Otherwise phased delivery avoids damage, theft and cash lockup.
How do I document quantities for change orders?
Record before-and-after measurements with dated photos, keep delivery tickets, and re-run the calculator for the changed scope. Paper trails get paid; memories do not.
What inspections relate to the rise and run calculator?
Anything structural, concealed or regulated gets inspected before covering: footings, steel, drains, waterproofing and rough-ins. Book inspections before the work that buries them.
How do I measure correctly for the rise and run calculator?
Measure twice with a tape or laser, write every reading down before typing it in, and keep one unit throughout. Photos of the tape protect you on disputed dimensions.
What units does the rise and run calculator use?
Whatever unit you select — pick one and use it for every field so conversions stay consistent. Results convert to the common trade units automatically.
How accurate is the rise and run calculator?
Exact for the numbers entered: all math runs at full precision and rounds only for display. Field accuracy depends on your measurements, so verify critical dimensions on site.
Can I use the rise and run calculator for bids and quotes?
Yes — the steps section shows the full working, and the breakdown table lists order quantities. Attach both to bids so clients see net figures and allowances separately.
Should I add waste or contingency to the result?
Yes. Add the trade waste factor (5–20% depending on material) before ordering, and carry a separate 5–10% budget contingency for price movement and surprises.
Why is my result different from my supplier quote?
Quotes include delivery, minimums, pack-size rounding, tax and regional pricing on top of bare quantities. Compare the net quantities first, then the add-ons.
Do I need a professional for this work?
Measuring and budgeting you can do yourself with this tool. Structural design, permits, licensed trades and inspections still need qualified professionals.
How do I convert the result to other units?
Use the results dashboard conversions, or the dedicated conversion calculators for length, area, volume and weight. Convert each linear dimension before combining into areas or volumes.

Related Calculators

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

Rise
Vertical change over a run.
Run
Horizontal distance over which rise is measured.
Slope percent
Rise ÷ run × 100.
Pitch
Roof slope as rise per 12 in of run.
Grade
Slope of ground or road, usually in percent.
ADA ramp
Accessible ramp limited to 8.33% (1:12) slope.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

ADA ramps: max 1:12 (8.33%) with landings and edge protectionDrainage falls: minimum ~1–2% away from structures100% slope = 45°; percent and degrees are not proportionalVerify steep or accessible slopes with a calibrated level

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Page Information

Last Updated:

2026-09-23

Version:

2.0.0

License:

Free to use for educational and professional purposes.