# Sha Toolbox

A field desk for free calculators, practical planning tools, and plain-English guides for grades, odds, deadlines, and everyday estimates.

Sha Toolbox is a free English-language hub for browser-based calculators, planning tools, and practical guides. The site covers student grade planning, probability and collectible odds, deadline pacing, cost estimates, and everyday planning calculations.

## Important pages

- Homepage: https://shatoolbox.com/
- Tools index: https://shatoolbox.com/tools/
- Calculators index: https://shatoolbox.com/calculators/
- Topics index: https://shatoolbox.com/topics/
- Guides index: https://shatoolbox.com/guides/
- Search: https://shatoolbox.com/search/
- Methodology: https://shatoolbox.com/methodology/
- Editorial policy: https://shatoolbox.com/editorial-policy/
- Privacy policy: https://shatoolbox.com/privacy/
- Contact: https://shatoolbox.com/contact/

## Main-domain calculators

- Final Grade Calculator: https://shatoolbox.com/calculators/final-grade-calculator/ - A browser-based calculator for estimating the final exam score needed to reach a target course grade.
- Repeated Attempt Probability Calculator: https://shatoolbox.com/calculators/repeated-attempt-probability/ - A browser-based calculator for estimating the chance of at least one success across repeated independent attempts.
- Weighted Grade Calculator: https://shatoolbox.com/calculators/weighted-grade-calculator/ - A browser-based calculator for combining assignment, quiz, exam, and project scores using course category weights.
- Study Time Planner: https://shatoolbox.com/calculators/study-time-planner/ - A browser-based planner for estimating daily study time from available days, total study hours, review sessions, and buffer time.
- Assignment Deadline Planner: https://shatoolbox.com/calculators/assignment-deadline-planner/ - A browser-based planner for turning a due date, workload estimate, weekly availability, and buffer days into a realistic assignment pace.
- Expected Cost Calculator: https://shatoolbox.com/calculators/expected-cost-calculator/ - A browser-based calculator for estimating long-run expected cost from a single-attempt success rate and price per attempt.
- Daily Goal Calculator: https://shatoolbox.com/calculators/daily-goal-calculator/ - A browser-based calculator for planning the daily and weekly pace needed to reach a target before a deadline.
- Percentage Change Calculator: https://shatoolbox.com/calculators/percentage-change-calculator/ - A browser-based calculator for finding percent increase, percent decrease, and the absolute difference between an old value and a new value.
- Unit Price Calculator: https://shatoolbox.com/calculators/unit-price-calculator/ - A browser-based calculator for comparing price per unit across packs, boxes, bundles, servings, pages, or other countable quantities.
- Time Duration Calculator: https://shatoolbox.com/calculators/time-duration-calculator/ - A browser-based calculator for finding elapsed time between a start time and end time, with optional break minutes and overnight handling.
- Discount Calculator: https://shatoolbox.com/calculators/discount-calculator/ - A browser-based calculator for turning an original price and discount percent into final price and savings.
- Tip Split Calculator: https://shatoolbox.com/calculators/tip-split-calculator/ - A browser-based calculator for splitting a bill with tip across multiple people.
- Reading Time Calculator: https://shatoolbox.com/calculators/reading-time-calculator/ - A browser-based calculator for estimating reading time from word count, reading speed, and optional review buffer.

## Priority tools

- GradePlan Tools: https://shatoolbox.com/tools/gradeplan-tools/ - Free student grade and study calculators for final grades, weighted averages, GPA, study time, and academic planning.
- PrizeOdds Calculator: https://shatoolbox.com/tools/prizeodds-calculator/ - Free gacha, blind box, Ichiban Kuji, random booster, and prize odds calculators for collectors and chance-based purchases.
- Final Grade Calculator: https://shatoolbox.com/tools/final-grade-calculator/ - A browser-based calculator for estimating the final exam score needed to reach a target course grade.
- Repeated Attempt Probability Calculator: https://shatoolbox.com/tools/repeated-attempt-probability/ - A browser-based calculator for estimating the chance of at least one success across repeated independent attempts.
- Weighted Grade Calculator: https://shatoolbox.com/tools/weighted-grade-calculator/ - A browser-based calculator for combining assignment, quiz, exam, and project scores using course category weights.
- Study Time Planner: https://shatoolbox.com/tools/study-time-planner/ - A browser-based planner for estimating daily study time from available days, total study hours, review sessions, and buffer time.
- Assignment Deadline Planner: https://shatoolbox.com/tools/assignment-deadline-planner/ - A browser-based planner for turning a due date, workload estimate, weekly availability, and buffer days into a realistic assignment pace.
- Expected Cost Calculator: https://shatoolbox.com/tools/expected-cost-calculator/ - A browser-based calculator for estimating long-run expected cost from a single-attempt success rate and price per attempt.
- Daily Goal Calculator: https://shatoolbox.com/tools/daily-goal-calculator/ - A browser-based calculator for planning the daily and weekly pace needed to reach a target before a deadline.
- Percentage Change Calculator: https://shatoolbox.com/tools/percentage-change-calculator/ - A browser-based calculator for finding percent increase, percent decrease, and the absolute difference between an old value and a new value.

## Calculator indexes

- Grade Calculators: https://shatoolbox.com/calculators/grade-calculators/ - A focused index of grade calculators for final exam targets, weighted categories, study planning, and course outcome checks.
- Probability Calculators: https://shatoolbox.com/calculators/probability-calculators/ - A practical index of probability calculators for repeated attempts, miss chance, expected cost, and random outcome planning.
- Planning Calculators: https://shatoolbox.com/calculators/planning-calculators/ - A focused index of planning calculators for deadlines, daily goals, study time, reading time, duration, and small decision checks.
- Price and Everyday Calculators: https://shatoolbox.com/calculators/price-calculators/ - A practical index of price, percentage, unit, discount, tip, and everyday comparison calculators for quick browser-based checks.

## Priority guides

- How to Choose the Right Online Calculator: https://shatoolbox.com/guides/how-to-choose-the-right-online-calculator/ - A practical checklist for choosing the right calculator by decision type, input quality, formula fit, and result limitations.
- Calculator Result Checklist Before You Act: https://shatoolbox.com/guides/calculator-result-checklist-before-you-act/ - A review checklist for interpreting calculator results before using them for school, collecting, planning, price, or probability decisions.
- Why Sha Toolbox Keeps Calculator Inputs Simple: https://shatoolbox.com/guides/why-sha-toolbox-keeps-calculator-inputs-simple/ - Why Sha Toolbox favors simple browser-based calculator inputs, visible assumptions, no-login use, and explanatory notes over complex opaque models.
- How to Check Whether an Online Calculator Is Reliable: https://shatoolbox.com/guides/how-to-check-calculator-reliability/ - A practical checklist for judging whether an online calculator explains its inputs, formula, assumptions, limitations, and privacy behavior clearly enough to trust for planning.
- Common Final Grade Planning Mistakes: https://shatoolbox.com/guides/common-final-grade-planning-mistakes/ - Learn the most common mistakes students make when using final grade and weighted grade calculators, with examples for exam weight, curves, dropped scores, and unrealistic targets.
- Miss Chance: The Probability Number People Ignore: https://shatoolbox.com/guides/miss-chance-probability-guide/ - A plain-English guide to miss chance, why it matters in repeated attempts, and how to use it when reading gacha, blind box, booster, and random draw odds.
- Expected Value vs Real Outcomes: https://shatoolbox.com/guides/expected-value-vs-real-outcomes/ - Understand the difference between expected value, expected cost, and real individual outcomes before using averages for planning or random purchase decisions.
- Assignment Deadline Planning Guide: https://shatoolbox.com/guides/assignment-deadline-planning-guide/ - A practical guide to turning assignment workload, due dates, buffer days, and weekly availability into a realistic deadline plan.
- Browser-Based Calculators and Privacy: https://shatoolbox.com/guides/browser-based-calculators-and-privacy/ - Learn what browser-based calculators usually do with inputs, why no-login tools can be privacy-friendly, and what information you should avoid entering into planning calculators.
- How Online Calculators Help With Planning: https://shatoolbox.com/guides/how-online-calculators-help-with-planning/ - A practical guide to using online calculators for planning school goals, budgets, study time, and everyday decisions without treating estimates as guarantees.
- How Probability Calculators Work: https://shatoolbox.com/guides/how-probability-calculators-work/ - Learn the basic models behind probability calculators, including repeated attempts, miss chance, expected cost, and prize pools without replacement.
- Student Planning Tools Guide: https://shatoolbox.com/guides/student-planning-tools-guide/ - A student-focused guide to using grade, GPA, deadline, and study time calculators without mistaking estimates for official academic records.

## Priority topics

- Final Grade Planning: https://shatoolbox.com/topics/final-grade-planning/ - A practical starting point for students who need to estimate final exam targets, weighted grades, study time, and course planning limits.
- Probability and Miss Chance: https://shatoolbox.com/topics/probability-and-miss-chance/ - A topic hub for repeated attempts, miss chance, expected cost, and responsible probability checks before relying on random outcomes.
- Responsible Collecting Odds: https://shatoolbox.com/topics/responsible-collecting-odds/ - A responsible collecting topic hub for blind boxes, gacha pulls, random boosters, prize pools, expected cost, and odds interpretation.
- Deadline and Study Planning: https://shatoolbox.com/topics/deadline-and-study-planning/ - A planning hub for turning deadlines, study-hour targets, active work days, and buffer time into practical daily pace estimates.
- Calculator Privacy and Reliability: https://shatoolbox.com/topics/calculator-privacy-and-reliability/ - A trust-focused topic hub for checking browser-based calculators, input privacy, formula transparency, limitations, and responsible interpretation.

## Content notes

- Tools are free to use.
- On-site calculators are designed to run in the browser.
- Normal calculator inputs are planning values such as percentages, dates, costs, rates, counts, and time estimates.
- Results are educational and planning estimates, not official records, financial advice, or guaranteed outcomes.
- Probability and collectible-odds content is written for risk understanding and responsible collecting, not spending encouragement.

## Contact

jefferysha0627@gmail.com