Conversion Table for Model Railroads
Origional from the Genesee "G" Gauge Railway Society of Rochester, New York
The following table was originally compiled by Bob Hardesty 4/00
The table is now generated by a computer program to facilitate additions.
Lastest update May 2005

Inches	Milli- meters	Twist Drill	B&S Wire	U.S. Plate	Tap Drill	Screw O.D.	Clear Drill	Scale Inches											Pin,Brad,Nail Diameters
								Z	N	HO	S	O	#1	G	G	G	F	1-inch
								1:220	1:160	1:87.1	1:64	1:48	1:32	1:29	1:24	1:22.5	1:20.3	1:12
.0003936	.0100							0.087	0.063	0.034	0.025	0.019	0.013	0.011	0.009	0.009	0.008	0.005
.001	.0254							0.220	0.160	0.087	0.064	0.048	0.032	0.029	0.024	0.022	0.020	0.012
.002	.0508							0.440	0.320	0.174	0.128	0.096	0.064	0.058	0.048	0.045	0.041	0.024
.003	.0762							0.660	0.480	0.261	0.192	0.144	0.096	0.087	0.072	0.068	0.061	0.036
.003145	.0799		40					0.692	0.503	0.274	0.201	0.151	0.101	0.091	0.075	0.071	0.064	0.038
.003531	.0897		39					0.777	0.565	0.308	0.226	0.169	0.113	0.102	0.085	0.079	0.072	0.042
.003965	.1007		38					0.872	0.634	0.345	0.254	0.190	0.127	0.115	0.095	0.089	0.080	0.048
.004	.1016							0.880	0.640	0.348	0.256	0.192	0.128	0.116	0.096	0.090	0.081	0.048
.004453	.1131		37					0.980	0.712	0.388	0.285	0.214	0.142	0.129	0.107	0.100	0.090	0.053
.005	.1270		36					1.100	0.800	0.436	0.320	0.240	0.160	0.145	0.120	0.113	0.102	0.060
.005614	.1426		35					1.235	0.898	0.489	0.359	0.269	0.180	0.163	0.135	0.126	0.114	0.067
.0059	.1499	#97						1.298	0.944	0.514	0.378	0.283	0.189	0.171	0.142	0.133	0.120	0.071
.006	.1524							1.320	0.960	0.523	0.384	0.288	0.192	0.174	0.144	0.135	0.122	0.072
.00625	.1587			38				1.375	1.000	0.544	0.400	0.300	0.200	0.181	0.150	0.141	0.127	0.075
.0063	.1600	#96						1.386	1.008	0.549	0.403	0.302	0.202	0.183	0.151	0.142	0.128	0.076
.006304	.1601		34					1.387	1.009	0.549	0.403	0.303	0.202	0.183	0.151	0.142	0.128	0.076
.0066406	.1687			37				1.461	1.062	0.578	0.425	0.319	0.212	0.193	0.159	0.149	0.135	0.080
.0067	.1702	#95						1.474	1.072	0.584	0.429	0.322	0.214	0.194	0.161	0.151	0.136	0.080
.007	.1720							1.540	1.120	0.610	0.448	0.336	0.224	0.203	0.168	0.158	0.142	0.084
.0070312	.1786			36				1.547	1.125	0.612	0.450	0.337	0.225	0.204	0.169	0.158	0.143	0.084
.00708	.1798		33					1.558	1.133	0.617	0.453	0.340	0.227	0.205	0.170	0.159	0.144	0.085
.0071	.1803	#94						1.562	1.136	0.618	0.454	0.341	0.227	0.206	0.170	0.160	0.144	0.085
.0075	.1905	#93						1.650	1.200	0.653	0.480	0.360	0.240	0.218	0.180	0.169	0.152	0.090
.0078125	.1948	1/128		35				1.719	1.250	0.680	0.500	0.375	0.250	0.227	0.188	0.176	0.159	0.094
.0078740	.2000	.20mm						1.732	1.260	0.686	0.504	0.378	0.252	0.228	0.189	0.177	0.160	0.094
.0079	.2007	#92						1.738	1.264	0.688	0.506	0.379	0.253	0.229	0.190	0.178	0.160	0.095
.00795	.2019		32					1.749	1.272	0.692	0.509	0.382	0.254	0.231	0.191	0.179	0.161	0.095
.008	.2032							1.760	1.280	0.697	0.512	0.384	0.256	0.232	0.192	0.180	0.162	0.096
.0083	.2108	#91						1.826	1.328	0.723	0.531	0.398	0.266	0.241	0.199	0.187	0.168	0.100
.0085937	.2183			34				1.891	1.375	0.749	0.550	0.412	0.275	0.249	0.206	0.193	0.174	0.103
.0097	.2210	#90						2.134	1.552	0.845	0.621	0.466	0.310	0.281	0.233	0.218	0.197	0.116
.008928	.2261		31					1.964	1.428	0.778	0.571	0.429	0.286	0.259	0.214	0.201	0.181	0.107
.009	.2286							1.980	1.440	0.784	0.576	0.432	0.288	0.261	0.216	0.202	0.183	0.108
.0091	.2231	#89						2.002	1.456	0.793	0.582	0.437	0.291	0.264	0.218	0.205	0.185	0.109
.009375	.2381			33				2.063	1.500	0.817	0.600	0.450	0.300	0.272	0.225	0.211	0.190	0.112
.0095	.2413	#88						2.090	1.520	0.827	0.608	0.456	0.304	0.275	0.228	0.214	0.193	0.114
.0098425	.2500	.25mm						2.165	1.575	0.857	0.630	0.472	0.315	0.285	0.236	0.221	0.200	0.118
.01	.2540	#87						2.200	1.600	0.871	0.640	0.480	0.320	0.290	0.240	0.225	0.203	0.120
.01003	.2548		30					2.207	1.605	0.874	0.642	0.481	0.321	0.291	0.241	0.226	0.204	0.120
.0101562	.2580			32				2.234	1.625	0.885	0.650	0.487	0.325	0.295	0.244	0.229	0.206	0.122
.0105	.2667	#86						2.310	1.680	0.915	0.672	0.504	0.336	0.304	0.252	0.236	0.213	0.126
.0109375	.2778			31				2.406	1.750	0.953	0.700	0.525	0.350	0.317	0.262	0.246	0.222	0.131
.0111	.2819	#85						2.442	1.776	0.967	0.710	0.533	0.355	0.322	0.266	0.250	0.225	0.133
.01126	.2860		29					2.477	1.802	0.981	0.721	0.540	0.360	0.327	0.270	0.253	0.229	0.135
.011481	.2916							2.526	1.837	1.000	0.735	0.551	0.367	0.333	0.276	0.258	0.233	0.138
.0115	.2921	#84						2.530	1.840	1.002	0.736	0.552	0.368	0.334	0.276	0.259	0.233	0.138
.011811	.3000	.30mm						2.598	1.890	1.029	0.756	0.567	0.378	0.343	0.283	0.266	0.240	0.142
.012	.3048	#83						2.640	1.920	1.045	0.768	0.576	0.384	0.348	0.288	0.270	0.244	0.144
.0125	.3175	#82		30				2.750	2.000	1.089	0.800	0.600	0.400	0.363	0.300	0.281	0.254	0.150
.01264	.3210		28					2.781	2.022	1.101	0.809	0.607	0.404	0.367	0.303	0.284	0.257	0.152
.013	.3302	#81						2.860	2.080	1.132	0.832	0.624	0.416	0.377	0.312	0.292	0.264	0.156
.0135	.0000	#80						2.970	2.160	1.176	0.864	0.648	0.432	0.392	0.324	0.304	0.274	0.162
.0137795	.3500	.35mm						3.031	2.205	1.200	0.882	0.661	0.441	0.400	0.331	0.310	0.280	0.165
.0140625	.3572			29				3.094	2.250	1.225	0.900	0.675	0.450	0.408	0.338	0.316	0.285	0.169
.01419	.3604		27					3.122	2.270	1.236	0.908	0.681	0.454	0.412	0.341	0.319	0.288	0.170
.0145	.3683	#79						3.190	2.320	1.263	0.928	0.696	0.464	0.421	0.348	0.326	0.294	0.174
.015	.3810							3.300	2.400	1.306	0.960	0.720	0.480	0.435	0.360	0.337	0.304	0.180
.015625	.3969	1/64		28	0000-160			3.438	2.500	1.361	1.000	0.750	0.500	0.453	0.375	0.352	0.317	0.188
.0157480	.4000	.40mm						3.465	2.520	1.372	1.008	0.756	0.504	0.457	0.378	0.354	0.320	0.189
.01594	.4049		26					3.507	2.550	1.388	1.020	0.765	0.510	0.462	0.383	0.359	0.324	0.191
.016	.4064	#78						3.520	2.560	1.394	1.024	0.768	0.512	0.464	0.384	0.360	0.325	0.192
.0171875	.4366			27				3.781	2.750	1.497	1.100	0.825	0.550	0.498	0.413	0.387	0.349	0.206
.0177165	.4500	.45mm						3.898	2.835	1.543	1.134	0.850	0.567	0.514	0.425	0.399	0.360	0.213
.0179	.4547		25					3.938	2.864	1.559	1.146	0.859	0.573	0.519	0.430	0.403	0.363	0.215
.018	.4572	#77						3.960	2.880	1.568	1.152	0.864	0.576	0.522	0.432	0.405	0.365	0.216
.01875	.4762			26				4.125	3.000	1.633	1.200	0.900	0.600	0.544	0.450	0.422	0.381	0.225
.019685	.5000	.50mm						4.331	3.150	1.715	1.260	0.945	0.630	0.571	0.472	0.443	0.400	0.236
.02	.5080	#76						4.400	3.200	1.742	1.280	0.960	0.640	0.580	0.480	0.450	0.406	0.240
.0201	.5150		24					4.422	3.216	1.751	1.286	0.965	0.643	0.583	0.482	0.452	0.408	0.241
.020833	.5392							4.583	3.333	1.815	1.333	1.000	0.667	0.604	0.500	0.469	0.423	0.250
.021	.5334	#75						4.620	3.360	1.829	1.344	1.008	0.672	0.609	0.504	0.473	0.426	0.252	Bnk,Sat.14,16,17
.0216535	.5500	.55mm						4.764	3.465	1.886	1.386	1.039	0.693	0.628	0.520	0.487	0.440	0.260
.021875	.5556			25				4.813	3.500	1.905	1.400	1.050	0.700	0.634	0.525	0.492	0.444	0.262
.0225	.5715	#74						4.950	3.600	1.960	1.440	1.080	0.720	0.652	0.540	0.506	0.457	0.270
.02257	.5733		23					4.965	3.611	1.966	1.444	1.083	0.722	0.655	0.542	0.508	0.458	0.271
.023	.5842							5.060	3.680	2.003	1.472	1.104	0.736	0.667	0.552	0.517	0.467	0.276	Nail,Escutch 24
.023622	.6000	.60mm						5.197	3.780	2.057	1.512	1.134	0.756	0.685	0.567	0.531	0.480	0.283
.024	.6096	#73					0000-160	5.280	3.840	2.090	1.536	1.152	0.768	0.696	0.576	0.540	0.487	0.288
.025	.6350	#72		24				5.500	4.000	2.177	1.600	1.200	0.800	0.725	0.600	0.563	0.508	0.300
.02535	.6439		22					5.577	4.056	2.208	1.622	1.217	0.811	0.735	0.608	0.570	0.515	0.304
.0255906	.6500	.65mm						5.630	4.094	2.229	1.638	1.228	0.819	0.742	0.614	0.576	0.519	0.307
.026	.6604	#71			000-120			5.720	4.160	2.265	1.664	1.248	0.832	0.754	0.624	0.585	0.528	0.312
.0275591	.7000	.70mm						6.063	4.409	2.400	1.764	1.323	0.882	0.799	0.661	0.620	0.559	0.331
.028	.7112	#70						6.160	4.480	2.439	1.792	1.344	0.896	0.812	0.672	0.630	0.568	0.336	Nail,Escutch 22
.028125	.7144			23				6.188	4.500	2.450	1.800	1.350	0.900	0.816	0.675	0.633	0.571	0.338
.02846	.7229		21					6.261	4.554	2.479	1.821	1.366	0.911	0.825	0.683	0.640	0.578	0.342
.029	.7366							6.380	4.640	2.526	1.856	1.392	0.928	0.841	0.696	0.653	0.589	0.348	Dr 14,16,17,Ba.14
.02925	.7429	#69						6.435	4.680	2.548	1.872	1.404	0.936	0.848	0.702	0.658	0.594	0.351
.0295276	.7500	.75mm						6.496	4.724	2.572	1.890	1.417	0.945	0.856	0.709	0.664	0.599	0.354
.03	.7620							6.600	4.800	2.613	1.920	1.440	0.960	0.870	0.720	0.675	0.609	0.360
.031	.7874	#68						6.820	4.960	2.700	1.984	1.488	0.992	0.899	0.744	0.698	0.629	0.372	Dress Pin 20
.03125	.7937	1/32		22				6.875	5.000	2.722	2.000	1.500	1.000	0.906	0.750	0.703	0.634	0.375
.0314961	.8000	.80mm						6.929	5.039	2.743	2.016	1.512	1.008	0.913	0.756	0.709	0.639	0.378
.03196	.8118		20					7.031	5.114	2.784	2.045	1.534	1.023	0.927	0.767	0.719	0.649	0.384
.032	.8128	#67						7.040	5.120	2.787	2.048	1.536	1.024	0.928	0.768	0.720	0.650	0.384	Nail,Escutch 21
.033	.8382	#66						7.260	5.280	2.874	2.112	1.584	1.056	0.957	0.792	0.743	0.670	0.396	Bank Pin 16,17
.0334646	.8500	.85mm			1.0mm			7.362	5.354	2.915	2.142	1.606	1.071	0.970	0.803	0.753	0.679	0.402
.034	.8636					000-120		7.480	5.440	2.961	2.176	1.632	1.088	0.986	0.816	0.765	0.690	0.408
.034375	.8731			21				7.563	5.500	2.994	2.200	1.650	1.100	0.997	0.825	0.773	0.698	0.413
.035	.8890	#65			00-90			7.700	5.600	3.049	2.240	1.680	1.120	1.015	0.840	0.788	0.711	0.420	Nail,Escutch 20
.00354331	.9000	.90mm						0.780	0.567	0.309	0.227	0.170	0.113	0.103	0.085	0.080	0.072	0.043
.03589	.9116		19					7.896	5.742	3.126	2.297	1.723	1.148	1.041	0.861	0.808	0.729	0.431
.036	.9144	#64						7.920	5.760	3.136	2.304	1.728	1.152	1.044	0.864	0.810	0.731	0.432	Drs.24,Bank 20
.037	.9398	#63