The right number, at the creek, in the storm在溪边、在风暴中，给出正确的数字
A free, bilingual, offline-first toolkit built for the hours when you cannot count on a signal, a shop or a clinic.一个免费、双语、离线优先的工具站，为没有信号、没有商店、没有诊所的那几个小时而建。
Mission
Wilderness survival is mostly arithmetic, judgment and preparation — and all three fail under stress, cold and fatigue. This site removes the arithmetic so your attention stays on judgment.
Every calculator here answers a question real hikers, campers, paddlers and mountaineers actually ask: how many drops, how many grams, how many minutes, how many meters of clearance. The tools load instantly, store your inputs privately on your own device, and work without a connection after the first visit — because the trailhead is exactly where cellular reception ends.
We serve two audiences with one interface: English-speaking travelers worldwide and Chinese-speaking outdoor communities (中文). All methodology text, FAQs, guides and emergency guidance are written natively in both languages, not machine-translated sentence by sentence.
How we build a calculator
1. Start with an authoritative source
Each tool begins from a named source: U.S. CDC and EPA guidance for chemical water disinfection; NOAA/NWS equations for heat index and wind chill; the Lake Louise acute-mountain-sickness score; the Pandolf load-carriage equation for walking energy expenditure; Naismith/book-time rules for hike duration; WGS-84 and US/NATO definitions for UTM and MGRS; international Morse timing standards. Sources are listed on every tool page and below.
2. Encode the formula, then test known vectors
Formulas are implemented as readable, dependency-free JavaScript. Each module is checked against published worked examples — 90 °F at 60% humidity gives a 99.7 °F heat index; 0 °F at 15 mph gives −19 °F wind chill; 3 miles with 2,000 feet of climb is a two-hour Naismith hike — plus edge cases and invalid input. Over six hundred automated assertions guard the logic.
3. State the limits loudly
Models are approximations. Lapse rates invert, terrain factors vary, bodies differ. Every tool shows its assumptions, the conditions where it stops being reliable and the human decision that follows. Nothing here tells you that you are “safe”; it gives you the best-supported estimate and the red flags.
4. Never lock safety behind money
All 28 tools and 15 guides are free, without accounts or paywalls. See our membership promise and the privacy policy.
Editorial boundaries
We deliberately do not publish: hunting or trapping instructions, weapons guidance, wild-mushroom or plant edibility identification (the failure mode is fatal and photographs are unreliable), or animal-killing methods. Snake information is provided as text-only description plus avoidance and bite-response steps. When in doubt, choose distance, retreat and a call to professionals.
使命
野外生存主要靠算术、判断与准备——而这三者都会在压力、寒冷与疲惫下失灵。本站负责消除算术，让你把注意力留给判断。
这里的每个计算器都回答徒步者、露营者、划水者与登山者真正会问的问题：几滴、几克、几分钟、几米净空。工具秒开，输入私密地保存在你自己的设备上，首次访问后断网可用——因为徒步起点往往正是手机信号的终点。
我们用一个界面服务两类读者：全球英语旅行者与中文户外社区。所有原理说明、FAQ、指南与应急指引均为双语原创，而非逐句机翻。
一个计算器是怎样建成的
1. 先找权威出处
每个工具都始于具名来源：美国 CDC 与 EPA 的化学饮水消毒指引、NOAA/NWS 的高温指数与风寒公式、Lake Louise 急性高原病评分、步行能耗的 Pandolf 负重方程、徒步时长的 Naismith/地图时间规则、UTM/MGRS 的 WGS-84 与美/北约定义、国际摩斯码时序标准。每个工具页下方与本页都列有出处。
2. 编码公式，再用已知向量测试
公式用可读、零依赖的 JavaScript 实现。每个模块都用公开的标准算例校验——90 °F、湿度 60% 的高温指数为 99.7 °F；0 °F、15 mph 风的风寒为 −19 °F；3 英里加 2000 英尺爬升对应 2 小时 Naismith 行程——并覆盖边界与非法输入。现有 600 多条自动化断言守护逻辑。
3. 大声说明局限
模型只是近似：递减率会反转、地形系数会变化、人体各有差异。每个工具都展示假设、失效条件以及随后需要人做的决定。本站不会告诉你“安全了”，只给最有依据的估算与红旗信号。
4. 安全功能绝不收费
28 个工具与 15 篇指南全部免费，无需账号、无付费墙。另见会员承诺与隐私政策。
内容边界
我们刻意不发布：捕猎或诱捕方法、武器指引、野生蘑菇或植物可食性鉴别（出错即致命，照片不可靠），以及杀死动物的方法。蛇类信息仅提供纯文字特征、规避与咬伤处置。拿不准时，永远优先拉开距离、撤退并联系专业人员。