Estimate Elevation Difference From Contour Intervals — Free
Count spaces between contour levels, not the number of printed lines. Calculate a vertical difference from indexed contours while keeping route distance and travel difficulty out of the answer.
The proof surface
Travel planners estimate itineraries. This is a classroom map-reading check of contour interval arithmetic, not a hiking route or an estimate of total ascent.
Why the flat version breaks
Counting both endpoint lines
Seven spaces separate eight successive contour lines.
Entering elevations as indices
Multiplying already-labelled metres by the interval double-counts the scale.
Treating net change as total ascent
Intermediate descents and climbs are absent from this model.
How to work the relief ladder
Copy the vertical contour interval in metres. Do not confuse thicker index-contour spacing with the interval between adjacent ordinary contour lines.
Number levels relative to any convenient reference, with the higher level having the larger index. These are indices, not the elevation labels printed on the map.
Upper index minus lower index gives the number of spaces. From index two to nine there are seven intervals, so the sample difference is 140 metres at twenty metres per interval.
This gives endpoint elevation difference only. A route that goes down and up can accumulate much more ascent, and the line spacing on paper controls steepness rather than this total alone.
What the relief ladder replaces
| Question | Before | Visible working |
|---|---|---|
| Counting both endpoint lines | Seven spaces separate eight successive contour lines. | Assign consistent contour indices |
| Entering elevations as indices | Multiplying already-labelled metres by the interval double-counts the scale. | Count intervals between endpoints |
| Treating net change as total ascent | Intermediate descents and climbs are absent from this model. | Keep the interpretation narrow |
A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.
Run it on the samples, right here
FIRST-LOAD
Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.
Educational arithmetic only, not navigation or outdoor safety advice. Use appropriate maps, skills and current local conditions for real routes.
Data note: Everything runs in this browser tab on the relief ladder: your map exercise | lower contour index | upper contour index stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a climbing rung ladder
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the relief ladder reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.
The relief ladder reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.
Open the estimate elevation difference from contour intervals companionBoundary
Educational arithmetic only, not navigation or outdoor safety advice. Use appropriate maps, skills and current local conditions for real routes.
What this is built on
- Method: Upper index minus lower index gives the number of spaces. From index two to nine there are seven intervals, so the sample difference is 140 metres at twenty metres per interval.
- All sample records are invented examples. The app does not fetch measurements, policies, files or personal records.
- Google’s official pricing page, fetched 2026-09-27, lists free-tier access including AI Studio. Optional formatting only; limits and availability can change. Free-tier content may be used to improve products. Never paste private records there.
Before: Seven spaces separate eight successive contour lines. After: the relief ladder shows the working beside each named row so the reader can change the assumption and inspect the consequence.
Optional AI formatting, not calculation
For this relief ladder, use the free AI Studio interface only if available to you, with no paid API key. Manual entry completes the same workflow for free. Supply only fictional or non-sensitive notes. Review its output against the source; never paste unresolved questions into the numeric rows.
Format my non-sensitive notes for a relief ladder. Return plain rows only: map exercise | lower contour index | upper contour index. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.
Accepted schema: map exercise | lower contour index | upper contour index. No AI response is executed as code.