Reference
Common scales reference
Documented scale conventions with the source each one comes from. These are references, not results: nothing on this page is derived from your inputs, and the calculators never round a calculated scale to a value listed here.
How to read the Status and Source columns
- Published standard — the ratio is listed in the cited standard from an issuing body. Those standards are voluntary unless a contract or authority makes them binding.
- Documented — a reliable published source records the value, without establishing it as a universal or mandatory scale.
- Common practice — established usage in the field with no published standard behind it. Manufacturers and ranges differ.
- Dates are shown as Document (the edition or date of the cited source) and Last verified (when SnapScaleCalc last checked that source). A last-verified date is not a publication or certification date.
- Conventions differ by field, country and era, and this list is not complete. Where the issuing body's current publication differs from anything here, that publication governs.
Filter by field
Model aircraft & vehicles
Widely used kit scales. These are industry conventions rather than a published standard, so treat them as common practice.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| 1:32 | 1:32 | 1:32 | Common practice | Large aircraft kits; also a common scale for classic car models. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:35 | 1:35 | 1:35 | Common practice | Dominant armour/military vehicle kit scale. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:48 | 1:48 | 1:48 | Common practice | Quarter inch to the foot; matches the architectural 1/4" = 1'-0" ratio. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:72 | 1:72 | 1:72 | Common practice | One sixth inch to the foot; the most common aircraft kit scale. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:144 | 1:144 | 1:144 | Common practice | Airliners and large aircraft in a compact size. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:24 | 1:24 | 1:24 | Common practice | Half inch to the foot; common for car kits. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
Model railways
Scale ratios listed by the NMRA standard for standard-scale track (US-based body; voluntary standards). Scale and track gauge are separate things, and the NMRA standard states the gauge separately from the ratio.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| HO — 1:87.1 | 1:87.1 | 1:87.1 | Published standard | 3.5 mm to the foot. NMRA HO scale, 16.5 mm standard gauge. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
| OO — 1:76.2 | 1:76.2 | 1:76.2 | Published standard | 4 mm to the foot, running on 16.5 mm gauge track. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
| N — 1:160 | 1:160 | 1:160 | Published standard | NMRA N scale, 9 mm standard gauge. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
| O — 1:48 | 1:48 | 1:48 | Published standard | Quarter inch to the foot. Listed as O scale, ratio 1:48, in NMRA S-3.2. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
| S — 1:64 | 1:64 | 1:64 | Published standard | 3/16 inch to the foot. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:22.5 (large scale, 45 mm gauge) | 1:22.5 | 1:22.5 | Published standard | Garden-railway ratio. NMRA S-3.2 covers it inside the "LS" large-scale group running on 45 mm gauge track (1:32, 1:29, 1:24, 1:22.5, 1:20.3) rather than as a named G scale; the letter G is trade usage. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
| TT — 1:120 | 1:120 | 1:120 | Published standard | 2.5 mm to the foot. | NMRA Standard S-3.2 — Track, Standard Scale (list of standard scales)Document: revision of 28 June 2026. Last verified by SnapScaleCalc: 28 August 2026. |
Miniatures & figures
Figure and wargaming scales. Ratios in this field are conventions and are often quoted alongside a figure height.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| 1:56 (28 mm) | 1:56 | 1:56 | Common practice | Common 28 mm wargaming convention. Figure heights vary between ranges. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:64 (25 mm) | 1:64 | 1:64 | Common practice | Older 25 mm figure convention. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:100 (15 mm) | 1:100 | 1:100 | Common practice | 15 mm historical and sci-fi ranges. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
| 1:12 | 1:12 | 1:12 | Common practice | One inch to the foot; standard dollhouse and large figure scale. | Common kit-industry practice — no published standard (see methodology)Last verified by SnapScaleCalc: 28 August 2026. |
Architecture (metric)
Metric drawing scales from the recommended series in ISO 5455 (technical drawings — scales). The full standard is a paid ISO publication, so only its scope and scale series were checked.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| 1:20 | 1:20 | 1:20 | Published standard | Detail drawings. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:50 | 1:50 | 1:50 | Published standard | Common plan and section scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:100 | 1:100 | 1:100 | Published standard | General arrangement plans. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:200 | 1:200 | 1:200 | Published standard | Whole-building and small site plans. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:500 | 1:500 | 1:500 | Published standard | Site plans. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
Architecture (imperial)
US architectural notation, where a drawing length in inches represents one foot of reality. The ratio follows arithmetically from the notation; the practice is US-specific and not a global standard.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| 1/4" = 1'-0" (1:48) | 1/4" = 1'-0" | 1:48 | Common practice | Standard US floor-plan scale. | US National CAD Standard, version 7 — overview (paid publication; US practice)Document: version 7. Last verified by SnapScaleCalc: 28 August 2026. |
| 1/8" = 1'-0" (1:96) | 1/8" = 1'-0" | 1:96 | Common practice | Larger buildings on a single sheet. | US National CAD Standard, version 7 — overview (paid publication; US practice)Document: version 7. Last verified by SnapScaleCalc: 28 August 2026. |
| 3/8" = 1'-0" (1:32) | 3/8" = 1'-0" | 1:32 | Common practice | Enlarged plans. | US National CAD Standard, version 7 — overview (paid publication; US practice)Document: version 7. Last verified by SnapScaleCalc: 28 August 2026. |
| 1/2" = 1'-0" (1:24) | 1/2" = 1'-0" | 1:24 | Common practice | Detail and millwork drawings. | US National CAD Standard, version 7 — overview (paid publication; US practice)Document: version 7. Last verified by SnapScaleCalc: 28 August 2026. |
| 1" = 1'-0" (1:12) | 1" = 1'-0" | 1:12 | Common practice | Large-scale details. | US National CAD Standard, version 7 — overview (paid publication; US practice)Document: version 7. Last verified by SnapScaleCalc: 28 August 2026. |
Engineering drawings
Reduction and enlargement scales from the recommended series in ISO 5455 for technical and engineering drawings. The full standard is a paid ISO publication.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| 1:2 | 1:2 | 1:2 | Published standard | ISO reduction scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:5 | 1:5 | 1:5 | Published standard | ISO reduction scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:10 | 1:10 | 1:10 | Published standard | ISO reduction scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:1 | 1:1 | 1:1 | Published standard | Full size. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 2:1 | 2:1 | 2:1 | Published standard | ISO enlargement scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 5:1 | 5:1 | 5:1 | Published standard | ISO enlargement scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
| 10:1 | 10:1 | 10:1 | Published standard | ISO enlargement scale. | ISO 5455:1979 — Technical drawings — Scales (paid ISO publication; scope page)Document: 1979 edition. Last verified by SnapScaleCalc: 28 August 2026. |
Maps
Representative fractions published by the US Geological Survey for its own map series. These are US mapping practice, not universal standards, though several ratios are used internationally.
| Name | Written as | Ratio | Status | Notes | Source |
|---|---|---|---|---|---|
| 1:24,000 | 1:24,000 | 1:24,000 | Documented | USGS 7.5-minute topographic quadrangle; 1 inch ≈ 2,000 feet. | USGS Fact Sheet 015-02 — Map ScalesDocument: 2002. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:25,000 | 1:25,000 | 1:25,000 | Documented | Common metric topographic series; 1 cm = 250 m. | USGS Fact Sheet 015-02 — Map ScalesDocument: 2002. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:50,000 | 1:50,000 | 1:50,000 | Documented | Standard topographic mapping; 1 cm = 500 m. | USGS Fact Sheet 015-02 — Map ScalesDocument: 2002. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:100,000 | 1:100,000 | 1:100,000 | Documented | Regional mapping; 1 cm = 1 km. | USGS Fact Sheet 015-02 — Map ScalesDocument: 2002. Last verified by SnapScaleCalc: 28 August 2026. |
| 1:250,000 | 1:250,000 | 1:250,000 | Documented | Small-scale regional overview mapping. | USGS Fact Sheet 015-02 — Map ScalesDocument: 2002. Last verified by SnapScaleCalc: 28 August 2026. |
How to use this table
A convention tells you what other people in a field have agreed to use. It does not tell you what your model, drawing or print actually is. Measure first, then compare.
Where two fields use nearly the same ratio the difference is usually significant in practice: 1:48 and 1:50 differ by about 4%, and 1:76 and 1:72 by about 5.5%. That is enough to make parts, figures and fittings incompatible even though the numbers look adjacent.
Scale and gauge are also different things. Model railway standards define both, and two products at the same scale can run on different gauges — check the standard, not the ratio.