Forget ratios. Here is where the extra women actually are.

Women minus men, ages 20–39, in each city's own census. 100 of 173 cities carry a female surplus — 1.10 million women in total.

Horizontal bar chart of the 28 cities with the largest surplus of women aged 20 to 39, led by Hanoi at 80,570

Bars are coloured by that city's ratio on the site's 94/100/112 scale. A big surplus with a moderate ratio simply means a big city.

Download the chart (PNG)

What the chart says

A ratio is a rate; nobody feels a rate. Hanoi's 94.3 sounds unremarkable until it is stated as 80,570 more women than men in the 20–39 band alone.
Size beats skew. The largest surpluses are big cities with moderate ratios, not small cities with extreme ones. The most female-skewed city on the site is nowhere near the top ten.

All 133

The chart shows 28. Here is every city carrying a surplus, largest first.

#	City	Country	Surplus women 20–39	Men per 100 women	Women 20–39	Men 20–39
1	Hanoi	Vietnam	80,570	94.3	1,407,817	1,327,247
2	São Paulo	Brazil	77,626	95.7	1,818,436	1,740,810
3	Rio de Janeiro	Brazil	63,227	93.3	948,788	885,561
4	Nairobi	Kenya	60,805	94.1	1,024,319	963,514
5	Salvador	Brazil	55,283	86.0	396,066	340,783
6	Ho Chi Minh City	Vietnam	48,436	98.2	2,646,563	2,598,127
7	Cali	Colombia	47,772	87.3	374,904	327,132
8	Yangon	Myanmar	44,170	92.0	549,292	505,122
9	Fortaleza	Brazil	35,822	91.3	413,110	377,288
10	Phnom Penh	Cambodia	34,715	93.6	539,745	505,030
11	Boca Chica	Dominican Republic	34,442	93.2	507,147	472,705
12	Malindi	Kenya	31,176	85.8	218,801	187,625
13	Warsaw	Poland	26,147	90.0	262,638	236,491
14	Kisumu	Kenya	20,697	89.2	191,802	171,105
15	New York City	United States of America	20,674	93.1	300,185	279,511
16	Nakuru	Kenya	20,418	94.3	357,223	336,805
17	Mawlamyine	Myanmar	20,179	88.0	168,346	148,167
18	Diani Beach	Kenya	19,636	84.3	124,694	105,058
19	Recife	Brazil	19,027	91.8	233,079	214,052
20	Guayaquil	Ecuador	18,996	95.6	428,703	409,707
21	Bogota	Colombia	18,185	98.7	1,388,903	1,370,718
22	Casablanca	Morocco	17,331	96.9	557,871	540,540
23	Santo Domingo	Dominican Republic	16,475	90.6	175,152	158,677
24	Quito	Ecuador	16,382	94.6	302,405	286,023
25	Minsk	Belarus	15,930	95.1	325,301	309,371
26	Marrakech	Morocco	14,887	93.3	221,823	206,936
27	Bucharest	Romania	13,926	94.8	265,430	251,504
28	Fez	Morocco	12,539	93.6	197,424	184,885
29	Córdoba	Argentina	12,276	95.2	253,256	240,980
30	Rosario	Argentina	11,263	94.7	213,228	201,965
31	Meknes	Morocco	11,050	91.8	135,490	124,440
32	Belgrade	Serbia	10,497	95.2	218,554	208,057
33	Mombasa	Kenya	9,531	96.2	251,611	242,080
34	Nay Pyi Taw	Myanmar	8,793	93.0	125,268	116,475
35	Santo Domingo	Ecuador	8,770	86.4	64,633	55,863
36	Jakarta	Indonesia	8,602	97.8	392,230	383,628
37	New Orleans	United States of America	8,562	85.7	60,040	51,478
38	Fukuoka	Japan	8,289	75.2	33,445	25,156
39	Cologne	Germany	7,904	95.1	159,887	151,983
40	Chicago	United States of America	7,873	99.0	766,594	758,721
41	Kraków	Poland	7,735	93.8	124,823	117,088
42	Nashville	United States of America	7,617	94.2	130,337	122,720
43	Rabat	Morocco	6,804	92.7	93,337	86,533
44	Boston	United States of America	6,765	95.7	157,454	150,689
45	Santiago de los Caballeros	Dominican Republic	5,944	96.5	170,145	164,201
46	Cartagena	Colombia	5,714	96.8	179,876	174,162
47	Duesseldorf	Germany	5,093	94.6	94,461	89,368
48	Pereira	Colombia	5,087	93.4	76,732	71,645
49	Wrocław	Poland	4,946	95.1	101,275	96,329
50	Sapporo	Japan	4,566	85.9	32,306	27,740
51	Cuenca	Ecuador	4,546	92.8	62,771	58,225
52	Atlanta	United States of America	4,403	97.5	173,645	169,242
53	Kampot	Cambodia	4,313	95.7	101,457	97,144
54	Gdańsk	Poland	4,238	94.0	70,088	65,850
55	Poznań	Poland	4,178	94.7	78,442	74,264
56	Toronto	Canada	4,160	99.1	447,180	443,020
57	Agadir	Morocco	4,109	96.0	103,526	99,417
58	Loja	Ecuador	3,984	89.5	37,858	33,874
59	Cluj-Napoca	Romania	3,865	90.8	41,812	37,947
60	La Plata	Argentina	3,859	96.9	124,808	120,949
61	Duran	Ecuador	3,822	92.2	49,225	45,403
62	Barranquilla	Colombia	3,806	98.2	215,231	211,425
63	San Miguel de Tucumán	Argentina	3,791	96.0	95,807	92,016
64	Mar del Plata	Argentina	3,591	96.2	95,037	91,446
65	Salta	Argentina	3,357	96.7	102,857	99,500
66	Manta	Ecuador	3,338	92.4	44,100	40,762
67	Riobamba	Ecuador	3,172	90.5	33,469	30,297
68	Machala	Ecuador	3,127	93.6	49,228	46,101
69	Osaka	Japan	3,016	85.1	20,198	17,182
70	Brest	Belarus	2,967	98.2	169,352	166,385
71	Gomel	Belarus	2,912	98.4	181,164	178,252
72	Montevideo	Uruguay	2,871	98.6	205,140	202,269
73	Portoviejo	Ecuador	2,817	93.2	41,456	38,639
74	Novi Sad	Serbia	2,802	94.8	53,864	51,062
75	Merida	Mexico	2,597	98.6	179,258	176,661
76	Bocas Town	Panama	2,432	89.6	23,437	21,005
77	Frankfurt am Main	Germany	2,377	98.0	121,657	119,280
78	Temuco	Chile	2,220	95.4	48,116	45,896
79	Lima	Peru	2,215	94.9	43,032	40,817
80	Angeles City	Philippines	2,172	97.4	83,631	81,459
81	Florianópolis	Brazil	2,066	97.8	94,006	91,940
82	Luque	Paraguay	2,032	95.9	49,972	47,940
83	Łódź	Poland	1,923	97.4	73,927	72,004
84	Tampa	United States of America	1,883	99.1	219,867	217,984
85	Vancouver	Canada	1,880	98.4	119,435	117,555
86	Brasov	Romania	1,774	94.4	31,694	29,920
87	Timisoara	Romania	1,718	95.2	35,664	33,946
88	Siem Reap	Cambodia	1,672	99.1	180,191	178,519
89	Asunción	Paraguay	1,669	97.8	76,184	74,515
90	Santa Marta	Colombia	1,625	98.3	94,630	93,005
91	Constanta	Romania	1,589	95.2	32,996	31,407
92	Ottawa	Canada	1,520	98.9	142,425	140,905
93	Oradea	Romania	1,504	94.3	26,174	24,670
94	Calgary	Canada	1,440	99.3	192,465	191,025
95	Colon	Panama	1,423	96.7	43,499	42,076
96	Phuket	Thailand	1,415	79.1	6,764	5,349
97	Buenos Aires	Argentina	1,318	96.7	39,631	38,313
98	Sibiu	Romania	1,273	93.2	18,648	17,375
99	Panama City	Panama	1,254	99.4	225,908	224,654
100	Cusco	Peru	1,245	87.6	10,014	8,769
101	Mandalay	Myanmar	1,203	99.6	342,528	341,325
102	Portland	United States of America	1,194	99.1	131,015	129,821
103	Surabaya	Indonesia	1,039	99.8	535,867	534,828
104	La Romana	Dominican Republic	1,027	97.6	43,495	42,468
105	Encarnación	Paraguay	979	95.9	23,874	22,895
106	Yogyakarta	Indonesia	958	98.8	80,798	79,840
107	Victoria	Canada	955	94.1	16,125	15,170
108	Coimbra	Portugal	800	95.1	16,164	15,364
109	Battambang	Cambodia	717	99.6	165,135	164,418
110	Hua Hin	Thailand	597	89.8	5,837	5,240
111	Arequipa	Peru	594	93.2	8,720	8,126
112	Braga	Portugal	580	97.6	24,500	23,920
113	Cascais	Portugal	527	97.7	22,433	21,906
114	Bariloche	Argentina	510	98.0	25,858	25,348
115	Dumaguete	Philippines	506	97.8	23,327	22,821
116	Limon	Costa Rica	496	95.1	10,039	9,543
117	Iasi	Romania	470	99.0	49,325	48,855
118	Porto	Portugal	457	98.4	28,664	28,207
119	Essaouira	Morocco	394	99.4	63,972	63,578
120	Pedro Juan Caballero	Paraguay	347	98.3	20,792	20,445
121	Taunggyi	Myanmar	331	99.8	209,487	209,156
122	San Pedro de Macorís	Dominican Republic	327	99.3	48,637	48,310
123	Pucón	Chile	243	95.0	4,829	4,586
124	Kragujevac	Serbia	190	99.1	20,472	20,282
125	Olomouc	Czechia	189	99.0	18,885	18,696
126	Hamburg	Germany	173	99.9	276,438	276,265
127	Ponta Delgada	Portugal	118	98.7	9,181	9,063
128	Funchal	Portugal	116	99.0	11,411	11,295
129	Villarrica	Paraguay	111	99.1	12,427	12,316
130	Faro	Portugal	97	98.8	7,991	7,894
131	Halifax	Canada	90	99.9	65,485	65,395
132	Portimão	Portugal	86	98.7	6,814	6,728
133	Kep	Cambodia	55	99.3	7,791	7,736

Surplus is women minus men in the 20–39 band, from that city's own census arrays. Cities with more men than women are excluded from this table by definition.

Where this is wrong

A surplus is not availability. It counts people in an age band. It says nothing about who is single, who is interested, or who would consider a foreigner.
23 cities are held back, not missing. Every UK city, and most of Taiwan, Thailand and South Korea, ship census arrays that are not population counts — a few hundred people against multi-million cities, and Belfast computing to 158 men per 100 women off 173 people. They are excluded until the source is rebuilt.
Population is the linked administrative unit, not always the metro. New York City's census arrays cover a borough, Mexico City's a delegación, Japan's four cities a ward. Those ratios are real ratios of real places, but read them as that unit rather than as the whole metro.
Surpluses do not add up across cities. Two cities of 20,000 each are not a pool of 40,000 to anyone who can only live in one of them.

Sources

Age by sex: national statistics offices, per market, at the finest published level — see methodology for the per-country source table. Built with Python and matplotlib; the renderer is geomax/viz/chart_suite.py.

The same numbers drive the research desk, where you can filter and sort every city here, and city rankings.

Sort every city by surplus →

Same numbers, filterable — and the sub-national maps at sex ratio by region break these markets down below city level.

The per-market deep-dives — 13 tabs of cost, visa, tax, safety and sub-national ratio for one country — are behind the Pro gate. Everything on this page is not.