Useful first. No ads. No spam.
Instant calculators run in your browser — zero signup, zero AI credits. AI preview tools show a real sample before you create a free account to edit and export in Studio.
Browse by role
Jump to the calculators that match how you work — creators, local business, quality, teams, and more.
Topic hubs
Curated collections for high-intent searches — converters, personal finance, pharma quality, and oil & gas engineering.
Free Unit Converters
Length, weight, volume, temperature — metric ↔ imperial, plus engineering and pharma units.
sciencePharma & GMP Quality Tools
USP compendial calculators, CAPA, OOS, stability, EM, and batch yield — free instant QA math.
account_balancePersonal Finance Calculators
Mortgage, DTI, emergency fund, 401(k), fuel costs, and rent vs buy — educational, not advice.
oil_barrelOil & Gas Engineering Calculators
PVT, productivity index, skin factor, decline, orifice flow, hoop stress, and pipe pressure drop.
Instant tools
Pure math in your browser — creators, local business, careers, marketing, presentations, and more. No account required.
Creators & solopreneurs
Instant
Freelance Rate Calculator
Billable hours, tax buffer, and business expenses — see gross vs take-home and the rate you actually need.
Use toolarrow_forward
Instant
Project Quote Builder
Labor, fixed fees, rush premium, and deposit split — see the full project total before you send the proposal.
Use toolarrow_forward
Instant
Break-Even Calculator
Fixed costs, price per unit, and variable cost — find break-even volume and profit at your target sales.
Use toolarrow_forward
Instant
Affiliate Earnings Estimator
Monthly visitors, click rate, conversion, and commission — estimate earnings and EPC in one view.
Use toolarrow_forward
Instant
Content Batch Planner
Posting cadence and minutes per post — see weekly hours raw vs batched, plus a simple batch-session plan.
Use toolarrow_forward
Instant
Invoice Late Fee Calculator
Calculate late fees and total due on overdue client invoices.
Use toolarrow_forwardBusiness & local
Instant
Menu Food-Cost & Margin Calculator
Ingredient cost, shrinkage, and target food cost — suggested menu price and profit per plate.
Use toolarrow_forward
Instant
Tip Pool Splitter
Pool total tips across staff with hours worked and role weights — see each person’s share and payout.
Use toolarrow_forward
Instant
Local Ad Budget Split
Set total monthly spend and channel percentages — see normalized splits when percentages do not sum to 100.
Use toolarrow_forward
Instant
Opening Hours Formatter
Set hours per day — get Google-friendly lines and a compact grouped format for directories.
Use toolarrow_forwardHiring & careers
Instant
Job Offer Comparison
Side-by-side total compensation for two job offers — recurring annual value and year-one including signing.
Use toolarrow_forward
Instant
Notice Period Planner
Enter resignation date and notice period — see last employment day and days until a new job starts.
Use toolarrow_forward
Instant
Interview Prep Timer (STAR)
Word count and speaking pace for behavioral answers — know if your story is too short, too long, or on target.
Use toolarrow_forward
Instant
Salary Reverse Calculator
Work backward from net pay — effective tax rate and pre-tax deductions to the gross offer you need.
Use toolarrow_forwardMarketing & social
Instant
Campaign Budget Allocator
Set total campaign budget and funnel-stage percentages — see normalized splits across the full journey.
Use toolarrow_forward
Instant
Social Aspect-Ratio Checker
Drop an image and pick a platform — preview center crop and whether your creative fits without trimming.
Use toolarrow_forward
Instant
Hashtag Density Checker
Paste a caption — see unique hashtags, density vs word count, and platform-specific recommendations.
Use toolarrow_forward
Instant
Email Subject Line Counter
Type a subject line — see character count, emoji tally, and how it truncates on mobile vs desktop.
Use toolarrow_forward
Instant
ROI Calculator
Campaign and project ROI from cost, gain, and time period.
Use toolarrow_forwardPresentations & docs
Instant
Pitch Timing Estimator
Slide count, pace per slide, intro, and Q&A buffer — compare total time to your allotted meeting.
Use toolarrow_forward
Instant
Print DPI / Pixel Calculator
Check DPI from pixel dimensions and print size, or calculate required pixels for 300 DPI export.
Use toolarrow_forward
Instant
Reading Time Calculator
Paste copy or enter word count. Reading time, speaking time, and optional slide pacing for decks.
Use toolarrow_forwardFinance & investing
Instant
Position Size Calculator
Plan risk per trade from account size, stop-loss pips, and pip value — see position size in lots and units.
Use toolarrow_forward
Instant
Pip Value Calculator
Major forex pairs with standard, mini, or micro lots — pip value in quote currency and USD.
Use toolarrow_forward
Instant
Compound Growth Simulator
Simulate compound returns over years with optional monthly contributions — year-by-year balance table.
Use toolarrow_forward
Instant
Mortgage Calculator
Estimate monthly principal & interest, escrow, total interest, and payoff impact from extra payments.
Use toolarrow_forward
Instant
Credit Card Payoff Calculator
Enter your balance, interest rate, and monthly payment — see payoff time, total interest, and how much you save compared with paying only the minimum.
Use toolarrow_forward
Instant
Personal Loan Calculator
Standard amortizing loan payment for personal, auto, or consolidation loans — compare APR before stretching term.
Use toolarrow_forward
Instant
Debt-to-Income Calculator
Estimate front-end (housing) and back-end (all debts) DTI ratios against common mortgage guidelines.
Use toolarrow_forward
Instant
Savings Goal Calculator
See how long it takes to reach a savings target with monthly contributions and a hypothetical annual return.
Use toolarrow_forward
Instant
Rent vs Buy Calculator
Compare total rent cost to estimated net ownership cost over a planning horizon — maintenance and appreciation included.
Use toolarrow_forward
Instant
Emergency Fund Calculator
Calculate emergency fund target from monthly expenses — 3-, 6-, or 12-month coverage, current gap, and timeline with monthly savings.
Use toolarrow_forward
Instant
Tip Calculator
Calculate tip amount, total, and per-person split for dining out.
Use toolarrow_forward
Instant
Fuel Cost Trip Calculator
Estimate gallons and total fuel cost for a trip; round-trip toggle included.
Use toolarrow_forward
Instant
401(k) Contribution Calculator
See annual 401(k) contributions, employer match, and remaining IRS room.
Use toolarrow_forward
Instant
Bi-weekly vs Monthly Mortgage
Compare monthly vs bi-weekly mortgage payments and total interest saved.
Use toolarrow_forwardTeams & productivity
Instant
Timezone Meeting Planner
Compare 2–3 timezones with configurable work hours — see overlap windows for global standups and reviews.
Use toolarrow_forward
Instant
Sprint Capacity Calculator
Model gross hours, ceremony load, PTO, and focus factor — net capacity in hours and person-days.
Use toolarrow_forward
Instant
Meeting Cost Calculator
Estimate per-meeting, weekly, and annual cost from attendees, duration, and hourly loaded rate.
Use toolarrow_forward
Instant
SLA Response Time Calculator
Measure support SLA compliance and average response vs target.
Use toolarrow_forwardQuality & compliance
Instant
Sample Size Calculator (A/B)
Two-proportion sample size with confidence and power — plan A/B tests without underpowered conclusions.
Use toolarrow_forward
Instant
CAPA Due-Date Tracker
Plan CAPA timelines from a non-conformance date — investigation, corrective action, and effectiveness check due dates.
Use toolarrow_forward
Instant
USP <71> Sterility Sampling Calculator
USP <71> sterility sampling — Table 3 articles by batch and product type, Table 2 minimum mL per medium, total test volume, and ×2 rule when fill is too small for two media.
Use toolarrow_forward
Instant
USP <85> Endotoxin Limit Calculator
Estimate bacterial endotoxin limits for parenterals using USP <85> K/M screening — parenteral vs intrathecal routes for LAL batch release planning.
Use toolarrow_forward
Instant
USP <788> Particulate Sampling Calculator
Calculate USP <788> particulate test sample size from batch article count — tier table aligned with injectable particulate examination planning.
Use toolarrow_forward
Instant
Reserve Sample Calculator (21 CFR 211.170)
Calculate minimum reserve sample quantity under 21 CFR 211.170 — twice the units consumed by release testing, with optional USP <71> sterility auto-fill.
Use toolarrow_forward
Instant
Stability Pull Schedule Planner
Generate stability study pull-point calendar from T0 — typical ICH long-term, accelerated, and intermediate time points for QC planning.
Use toolarrow_forward
Instant
OOS Retest Calculator
Screen assay or content-uniformity results against L1/L2 limits — see if retest units are indicated before full OOS investigation.
Use toolarrow_forward
Instant
Hold Time Tracker
Track manufacturing hold time from last clean — hours remaining or excursion for batch campaign and equipment use planning.
Use toolarrow_forward
Instant
Cleanroom EM Excursion Calculator
Compare cleanroom particle counts to EU GMP Grade A–D action and alert limits — normalized per m³ for EM excursion screening.
Use toolarrow_forward
Instant
Batch Yield Calculator
Calculate batch yield percentage and loss for pharma manufacturing reconciliation.
Use toolarrow_forwardEngineering & energy
Instant
Darcy Skin Factor Calculator
Calculate skin factor from stabilized test rate or estimate liquid rate from skin — oilfield Darcy radial flow screening.
Use toolarrow_forward
Instant
Petroleum PVT & Bubble Point Calculator
Estimate bubble-point pressure and oil PVT properties (Rs, Bo) with Standing (1977) — field units for reservoir and production screening.
Use toolarrow_forward
Instant
Well Productivity Index Calculator
Compute liquid rate q = J(Pr − Pwf) or productivity index from a stabilized well test — reservoir engineering screening.
Use toolarrow_forward
Instant
Hyperbolic Decline & EUR Calculator
Hyperbolic decline curve calculator for oil and gas — estimate rate, Np, and EUR to a cutoff rate with Arps b-factor.
Use toolarrow_forward
Instant
Hoop Stress & Wall Thickness Calculator
Pressure vessel and pipe hoop stress with ASME VIII Div 1 style required thickness — mechanical engineering screening.
Use toolarrow_forward
Instant
Gas Orifice & Choke Flow Calculator
Estimate gas rate through a choke or orifice plate — choked vs subcritical flow with discharge coefficient and gas properties.
Use toolarrow_forward
Instant
Euler Column Buckling Calculator
Euler column buckling for slender members — critical load and effective length with standard end conditions.
Use toolarrow_forward
Instant
Pipe Pressure Drop Calculator
Estimate pipe pressure drop in psi from flow rate and pipe geometry.
Use toolarrow_forwardStudents & science
Instant
Interactive Periodic Table
Color-coded periodic table for students. Search by name or symbol, filter by metal type, copy element facts.
Use toolarrow_forward
Instant
Molar Mass Calculator
Parse chemical formulas and compute molar mass; optional grams-to-moles.
Use toolarrow_forwardUnit converters
Instant
Unit Converter
Free universal unit converter: meters to feet, kg to lbs, liters to gallons, °C to °F.
Use toolarrow_forward
Instant
Engineering Unit Converter
Convert pressure and petroleum volumes — psi to bar, bbl to m³, scf to sm³.
Use toolarrow_forward
Instant
Pharma Unit Converter
Pharmaceutical mass and concentration conversions for QA and formulation homework.
Use toolarrow_forward
AI previews
Real AI output in under a minute — unlock the full draft, score, or export with a free account.
~60 sec
AI Resume Builder
ATS-ready resume preview. Unlock full draft, strength score, and PDF export — free.
Try freearrow_forward
Instant scan
Website SEO Checker
SEO score + Google preview. Unlock the full audit, playbooks, and AI fixes in SEO Studio.
Try freearrow_forward
~60 sec
Cover Letter Writer
Role-specific letter from any job post. Preview the hook free — full letter in Resume Studio.
Try freearrow_forwardTwo ways to get value
Instant tools
Calculators and formatters — full utility immediately. Copy results, share the link, come back anytime.
AI previews
Resume, SEO, and cover letter teasers — then create a free account to edit with AI coaches and export.