Three ways to write one point on Earth
A single place on the surface of the Earth has three everyday addresses. Decimal degrees, shown as DD, write latitude and longitude as signed numbers between −90 to 90 and −180 to 180 — this is the compact form used by phones, GPS chips and most data files. Degrees, minutes and seconds, shown as DMS, are the older navigational form: one degree is sixty minutes and one minute is sixty seconds, with an N or S letter for latitude and an E or W letter for longitude. A GeoHash is the third form: the world is repeatedly cut in half, alternating between longitude and latitude, and every five yes-or-no decisions are encoded as one character from a thirty-two symbol base32 alphabet that deliberately omits confusing letters.
This page keeps all three forms live at the same time. Type into any one of the groups and the other two update immediately. Converting decimal degrees to DMS separates the fractional part, multiplies it by sixty to get minutes, and repeats the operation once more for seconds; converting back adds degrees, minutes divided by sixty and seconds divided by thirty-six hundred, then restores the sign from the hemisphere selector. Minutes and seconds outside their zero-to-sixty range are rejected on the spot, and latitudes or longitudes beyond the legal bounds are flagged instead of silently wrapping.
The GeoHash always runs at precision nine, which narrows the containing rectangle to a few metres around the point — easily sharper than a poster can ever print. Decoding walks each character from most significant bit to least, assigning even bits to longitude intervals and odd bits to latitude intervals, and the center of the recovered rectangle feeds the decimal and DMS fields. Because the hash only describes a rectangle, tiny last-digit differences between encode and decode are normal, not rounding errors.
A result card worth keeping
The preview renders the answer not as plain text but as a finished coordinate card: three monospace rows separated by fine rules, corner registration marks and a small crosshair motif, all repainted at 300 dots per inch when you download. The copy button places all three rows on your clipboard through the clipboard API and falls back to a prompt dialog in browsers that block it, so the result can always be pasted into a message or a spreadsheet. Everything runs locally, with no network calls at any point.
地球上同一个点的三种写法
地球表面的同一个地点，有三种常用的地址写法。十进制度（DD）把纬度与经度写成带符号的数字，纬度介于 −90 到 90、经度介于 −180 到 180，这是手机、GPS 芯片与大多数数据文件使用的紧凑格式。度分秒（DMS）是更古老的航海写法：一度等于六十分，一分等于六十秒，再用 N/S 表示南北纬、E/W 表示东西经。第三种是 GeoHash：把世界反复对半切分，经度与纬度交替进行，每五个「是或否」的判断就编码成一个字符，字符来自一套三十二个符号的 base32 字母表，并刻意剔除了容易混淆的字母。
本页让三种格式同时保持有效：你在任意一组里输入，另外两组都会立刻更新。十进制度转度分秒时，取出小数部分先乘以六十得到分，再对分的小数乘一次六十得到秒；反向换算时则把度、分除以六十、秒除以三千六百相加，最后用半球选择器恢复正负号。一旦分或秒落在零到六十的合法区间之外，页面会当场提示；经纬度超出各自范围时也会明确报错，而不是偷偷把数值折回。
GeoHash 固定使用九位精度，对应的矩形范围只有几米见方，远比任何海报能够印刷的精度更细。解码时从每个字符的最高位向最低位逐位处理：偶数位切分经度区间，奇数位切分纬度区间，再用恢复出的矩形中心回填十进制与度分秒字段。由于哈希描述的本来就是一个矩形，编码再解码后最后一位出现极小差异是正常现象，并非计算误差。
一张值得保存的结果卡
预览区不会把答案显示成干巴巴的文本，而是渲染成一张完整的坐标卡：三行等宽字体坐标以细线分隔，配上四角对位标记与小型十字准星图案；下载时整卡再以每英寸 300 点重绘。复制按钮通过剪贴板接口把三行内容一起放入剪贴板，若浏览器拦截剪贴板，则回退到弹窗对话框，保证结果总能粘进消息或表格。全部计算在本地完成，过程中没有任何网络请求。
Why does editing the GeoHash slightly move my coordinates?
A GeoHash describes a rectangle, not a point. When the hash is decoded, the form fills with the center of that rectangle. At precision nine the rectangle is only a few metres wide, so the shift is negligible for travel and completely invisible on any printed map. If you need the exact original decimals, edit the DD fields instead and let the hash regenerate.
为什么修改 GeoHash 后坐标会轻微移动？
GeoHash 描述的是一个矩形而不是一个点。解码时表单填入的是该矩形的中心。九位精度下矩形只有几米见方，对出行使用可以忽略，印在任何地图上都完全看不出差别。如果你需要最初的精确小数值，请直接修改十进制字段，让哈希重新生成。
How do I type southern or western coordinates in DMS?
Keep degrees, minutes and seconds as positive numbers and choose S for south latitude or W for west longitude in the hemisphere selector. Minutes and seconds must stay below sixty — if you have 65 seconds, carry ten seconds into the minutes field first, just as you would when adding time. Avoid typing negative values into the DMS boxes; signs belong to the hemisphere letters only.
南纬、西经的度分秒要怎么输入？
度、分、秒都填写非负数字，再在半球选择器中为纬度选 S（南）或为经度选 W（西）。分和秒必须小于六十：如果你有 65 秒，请先像做时间加法一样，把 60 秒进位为 1 分。不要在度分秒输入框里填负数，正负号只由半球字母表达。
Can I export and print the result card?
Yes. Download redraws the card at 300 DPI in whichever print size you select, from A4 to gallery formats, so the monospace coordinates remain crisp rather than screenshot-blurry. It is a genuine PNG image you can attach to an itinerary, print as a reference card, or keep inside a travel journal.
结果卡可以导出并印刷吗？
可以。下载时会按你选择的尺寸——从 A4 到画廊尺寸——以 300 DPI 重绘整卡，等宽坐标保持锐利，不会像截图那样发虚。它是一张真正的 PNG 图片，可以附进行程单、印成随身参考卡，或夹进旅行手账。
