About Big Rig Math

Big Rig Math is a free reference for truck drivers, owner-operators and small fleets. It does two things: it runs the arithmetic that decides whether a load pays, and it explains the federal hours-of-service rules in plain language with the regulation cited so you can check us. Everything runs in your browser. No sign-up or account is needed to use anything here, and there is nothing to install.

What is actually here

Calculators. The truck fuel cost calculator turns miles, MPG and diesel price into a trip fuel figure. The cost per mile calculator works out what a mile actually costs you once fixed and variable costs are counted, which is the number that tells you whether a rate is profitable. The IFTA calculator works out the quarterly fuel-tax position for one jurisdiction at a time: the gallons you burned there, less the tax-paid gallons you bought there, at the rate you enter. The fuel surcharge calculator works out what a DOE-peg surcharge should pay at this week's EIA diesel price and whether it covers your truck's real fuel burn. The factoring cost calculator shows what getting paid today costs, in dollars, as a share of the invoice, and annualized. The factoring rate check asks a few questions, estimates the rate our factoring partner's pricing guide puts you at, and passes your details to that partner only if you ask it to.

Clock and weight tools. These live on their own subdomains: the split sleeper berth planner shows your 11- and 14-hour clocks and checks 7/3 and 8/2 splits, the 70-hour/8-day recap calculator tracks your rolling 60/70-hour total, and the axle weight and tandem slide calculator turns a scale ticket into how many holes to slide your tandems. Bus, motorcoach and charter drivers run on different limits under 49 CFR 395.5, so they have their own set at coach.bigrigmath.com: a 10/15-hour shift calculator, a 60/70-hour recap and a sleeper berth split checker.

Cost and filing guides. IFTA quarterly filing deadlines tells you when each quarter is due and how a deadline that lands on a weekend or legal holiday moves to the next business day, and the deadhead miles cost guide shows how to price the empty miles most rate calculations quietly ignore.

Hours-of-service guides. One page per rule, because the rules are individually simple and collectively easy to get wrong when several clocks run at once: the rules overview, the 11-hour driving limit, the 14-hour window, the 30-minute break, the 34-hour restart and split sleeper berth basics.

Exceptions and exemptions, which is where most confusion lives: adverse driving conditions, the short-haul 150 air-mile exemption, personal conveyance, the ELD mandate and its exemptions, and the agricultural exemption.

Why we built it

The hours-of-service rules in 49 CFR 395 are short, but they interact. A driver can be legal on the 11-hour clock and illegal on the 14-hour clock at the same moment, and the exceptions each carry conditions that are easy to half-remember. The cost side has the mirror problem: a rate per mile looks fine until deadhead, fuel and fixed costs are counted honestly, and by then the load is booked. Most of what exists online is either a lead-capture form wearing a calculator's face, or an app that wants an account before it will tell you a number. We wanted the number, immediately, with the reasoning shown.

What this is not

These tools are advisory planning aids, not a compliance record. Your electronic logging device and your carrier's logs are the authoritative account of your hours; a certified scale is the authority on your weights; and your accountant and your state's tax authority are the authority on what you owe. Use these to understand and plan, then confirm every number against the official record before you drive or file. We cite the regulation on each guide page precisely so you can go and read the source rather than take our word for it. If a rule changes and a page here is stale, that is a bug and we would like to hear about it.

How this site is paid for

Big Rig Math is free and always will be. It is supported by display advertising and by referral arrangements with service providers relevant to trucking, such as freight factoring. If you ask us to introduce you to one of those providers and you become a funded customer, we are paid a referral fee, at no cost to you. Some pages also carry affiliate links. As an Amazon Associate we earn from qualifying purchases made through our Amazon product links, and the Audible trial link on some guides can pay us a commission if you start a trial. None of these costs you anything extra. We say this plainly because a calculator that quietly steers you toward whoever pays it is worthless, and because you should know what our incentives are before you weigh our recommendations. A referral relationship never changes what a calculator computes.

Who runs it

Big Rig Math is operated by Crossroads Technologies, LLC, a small independent publisher of free web utilities. We are not a carrier, a broker, a factoring company or a law firm, and we have no affiliation with the Federal Motor Carrier Safety Administration or any government agency. Corrections, rule updates and requests for tools we have not built yet are genuinely welcome through the contact page.